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Persaud KE, Sahu RR, Neary MC, Kapdi AR, Lakshman MK. Two short approaches to the COVID-19 drug β-D- N4-hydroxycytidine and its prodrug molnupiravir. Org Biomol Chem 2024; 22:735-740. [PMID: 38168802 DOI: 10.1039/d3ob02039h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Molnupiravir, the prodrug for β-D-N4-hydroxycytidine (NHC), is marketed by Merck as Lagevrio™ against mild-moderate COVID-19, under FDA emergency use authorization. It is the first oral drug against the disease. This work describes two synthetic approaches to NHC and molnupiravir by amide activation in uridine with a peptide-coupling agent and with a 4-chloropyrimidinone nucleoside intermediate.
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Affiliation(s)
- Kevin E Persaud
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Rajesh R Sahu
- Department of Chemistry, Institute of Chemical Technology, Nathalal Parekh Road, Matunga, Mumbai 400019, India
| | - Michelle C Neary
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, NY 10065, USA
| | - Anant R Kapdi
- Department of Chemistry, Institute of Chemical Technology, Nathalal Parekh Road, Matunga, Mumbai 400019, India
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
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2
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Lakshman MK, Sebastian D, Pradhan P, Neary MC, Piette AM, Trzebiatowski SP, Henriques AEK, Willoughby PH. Nitrene C-H Bond Insertion Approach to Carbazolones and Indolones, and a Reactivity Departure for 7-Membered Analogues. Chemistry 2023; 29:e202302995. [PMID: 37751465 DOI: 10.1002/chem.202302995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 09/25/2023] [Accepted: 09/26/2023] [Indexed: 09/28/2023]
Abstract
A modular platform for facile access to 1,2,3,9-tetrahydro-4H-carbazol-4-ones (H4 -carbazolones) and 3,4-dihydrocyclopenta[b]indol-1(2H)-ones (H2 -indolones) is described. The requisite 6- and 5-membered 2-arylcycloalkane-1,3-dione precursors were readily obtained through a Cu-catalyzed arylation of 1,3-cyclohexanediones or by a ring expansion of aryl succinoin derivatives. Enolization of one carbonyl group in the diones, conversion to a leaving group, and subsequent azidation gave 2-aryl-3-azidocycloalk-2-en-1-ones. This two-step, one-pot azidation is highly regioselective with unsymmetrically substituted 2-arylcyclohexane-1,3-diones. The regioselectivity, which is important for access to single isomers of 3,3-disubstituted carbazolones, was analyzed mechanistically and computationally. Finally, a Rh-catalyzed nitrene/nitrenoid insertion into the ortho C-H bond of the aryl moiety gave the H4 -carbazolones and H2 -indolones. One carbazolone was elaborated to an intermediate reported in the total synthesis of N-decarbomethoxychanofruticosinate, (-)-aspidospermidine, (+)-kopsihainanine A. With 2-phenylcycloheptane-1,3-dione, prepared from cyclohexanone and benzaldehyde, the azidation reaction was readily accomplished. However, the Rh-catalyzed reaction unexpectedly led to a labile but characterizable azirine rather than the indole derivative. Computations were performed to understand the differences in reactivities of the 5- and 6-membered 2-aryl-3-azidocycloalk-2-en-1-ones in comparison to the 7-membered analogue, and to support the structural assignment of the azirine.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
- The Graduate Center of the City University of New York, The Ph.D. Program in Chemistry, 365 Fifth Avenue, New York, NY 10016, USA
| | - Dellamol Sebastian
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
- The Graduate Center of the City University of New York, The Ph.D. Program in Chemistry, 365 Fifth Avenue, New York, NY 10016, USA
| | - Padmanava Pradhan
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Michelle C Neary
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, NY 10065, USA
| | - Alexis M Piette
- Department of Chemistry, Ripon College, 300 W. Seward St., Ripon, WI 54971, USA
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Kapdi AR, Arseniyadis S, Lakshman MK. Nucleoside/Nucleotide or Nucleic Acid Modification & Applications. CHEM REC 2023; 23:e202200252. [PMID: 36623938 DOI: 10.1002/tcr.202200252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
"The field of nucleosides, nucleotides, and nucleic acids has been in existence for some decades, leading to a notion that the area is well-explored and/or specialized, but is that true? Despite the constant reliance on this field for various aspects of biochemical, biological, and biomedical research, recent advances have brought this area into a greater focus, with the potential and benefits becoming increasingly evident. Explore this Special Collection for rich, diverse, and state-of-the art research presented in the form of Personal Accounts, Reviews, and Research Articles."
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Affiliation(s)
- Anant R Kapdi
- Institute of Chemical Technology, 400019, Mumbai, India
| | | | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, 160 Convent Avenue, New York, NY 10031, USA
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Lakshman MK. Base Modifications of Nucleosides via the Use of Peptide-Coupling Agents, and Beyond. CHEM REC 2023; 23:e202200182. [PMID: 36166699 DOI: 10.1002/tcr.202200182] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 08/26/2022] [Indexed: 01/24/2023]
Abstract
Several naturally occurring purine and pyrimidine nucleosides contain an amide linkage as part of the heterocyclic aglycone. Enolization of the amide and conversion to leaving groups at the amide carbon atom permits base modification by addition-elimination types of processes. Although a number of methods have been developed over the years for accomplishing such conversions, the present Personal Account describes efforts from the Lakshman laboratories. Facile activation of the amido groups in nucleobases can be achieved with peptide-coupling agents. Subsequent reaction with nucleophiles then accomplishes the base modifications. In many cases, the activation and displacement steps can be done as two-step, one-pot processes, whereas in other cases, discrete storable activated nucleosides can be isolated for subsequent displacement reactions. Using such an approach a wide range of nucleoside base modifications is readily achievable. In many instances, mechanistic investigations have been conducted so as to understand the activation process.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
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Kapdi AR, Arseniyadis S, Lakshman MK. Cover Picture: Nucleoside/Nucleotide or Nucleic Acid Modification & Applications (Chem. Rec. 1/2023). CHEM REC 2023. [DOI: 10.1002/tcr.202380101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
| | | | - Mahesh K. Lakshman
- Department of Chemistry and Biochemistry 160 Convent Avenue New York NY 10031 USA
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Akula HK, Bae S, Pradhan P, Yang L, Zajc B, Lakshman MK. Diversely C8-functionalized adenine nucleosides via their underexplored carboxaldehydes. Chem Commun (Camb) 2022; 58:1744-1747. [PMID: 35029254 DOI: 10.1039/d1cc06686b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potentially versatile N-unprotected 8-formyl derivatives of adenosine and 2'-deoxyadenosine are highly underexploited for C8 modifications of these nucleosides. Only in situ formation of 8-formyladenosine is known and a single application of an N-benzoyl derivative has been reported. On the other hand, 8-formyl-2'-deoxyadenosine and its applications remain unknown. Herein, we report straightforward, scalable syntheses of both N-unprotected 8-formyladenine nucleoside derivatives, and demonstrate broad diversification at the C8 position by hydroxymethylation, azidation, CuAAC ligation, reductive amination, as well as olefination and fluoroolefination with modified Julia and a Horner-Wadsworth-Emmons reagents.
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Affiliation(s)
- Hari K Akula
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Suyeal Bae
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Padmanava Pradhan
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Lijia Yang
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Barbara Zajc
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA. .,The PhD Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA. .,The PhD Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
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Abstract
To a large extent, the physical and chemical properties of peptidomimetic molecules are dictated by the integrated heterocyclic scaffolds they contain. Heterocyclic moieties are introduced into a majority of peptide-mimicking molecules to modulate conformational flexibility, improve bioavailability, and fine-tune electronics, and in order to achieve potency similar to or better than that of the natural peptide ligand. This mini-review delineates recent developments, limited to the past five years, in the utility of selected saturated 3- to 6-membered heterocyclic moieties in peptidomimetic design. Also discussed is the chemistry involved in the synthesis of the azaheterocyclic scaffolds and the structural implications of the introduction of these azaheterocycles in peptide backbones as well as side chains of the peptide mimics.
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Affiliation(s)
- Manish K Singh
- Department of Science, Technology, and Mathematics, Lincoln University, 820 Chestnut Street, Jefferson City, Missouri 65101, USA.
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
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Sebastian D, Willoughby PH, Lakshman MK. Cross-dehydrogenative coupling of ethers and amides with the tautomerizable quinazolinones, and mechanistic studies. Org Biomol Chem 2022; 20:5735-5746. [DOI: 10.1039/d2ob00874b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cross-dehydrogenative coupling reactions have been utilized to alkylate 4(3H)-quinazolinones with ethers and amides, using catalytic n-Bu4NI and t-BuOOH as oxidant. Reactions with amides represent the first examples under such conditions....
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Abstract
Among the C6-halo purine ribonucleosides, the readily accessible 6-chloro derivative has been known to undergo slow SNAr reactions with amines, particularly aryl amines. In this work, we show that in 0.1 M AcOH in EtOH, aryl amines react quite efficiently at the C6-position of 2',3',5'-tri-O-(t-BuMe2Si)-protected 6-chloropurine riboside (6-ClP-riboside), with concomitant cleavage of the 5'-silyl group. These two-step processes proceeded in generally good yields, and notably, reactions in the absence of AcOH were much slower and/or lower yielding. Corresponding reactions of 2',3',5'-tri-O-(t-BuMe2Si)-protected 6-ClP-riboside with alkyl amines proceeded well but without desilylation at the primary hydroxyl terminus. These differences are likely due to the acidities of the ammonium chlorides formed in these reactions, and the role of AcOH was not desilylation but possibly only purine activation. With 50% aqueous TFA in THF at 0 °C, cleavage of the 5'-silyl group from 2',3',5'-tri-O-(t-BuMe2Si)-protected N6-alkyl adenosine derivatives and from 6-ClP-riboside was readily achieved. Reactions of the 5'-deprotected 6-ClP-riboside with alkyl amines proceeded in high yields and under mild conditions. Because these complementary methodologies yielded N6-aryl and -alkyl adenosine derivatives containing a free 5'-hydroxyl group, a variety of product functionalizations were undertaken to yield N6,C5'-doubly modified nucleoside analogues.
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Affiliation(s)
- Dellamol Sebastian
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Sakilam Satishkumar
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Padmanava Pradhan
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Lijia Yang
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States
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Korvinson KA, Akula HK, Malinchak CT, Sebastian D, Wei W, Khandaker TA, Andrzejewska MR, Zajc B, Lakshman MK. Cover Picture: Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine (Adv. Synth. Catal. 1/2020). Adv Synth Catal 2019. [DOI: 10.1002/adsc.201901549] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kirill A. Korvinson
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
| | - Hari K. Akula
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
| | - Casina T. Malinchak
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
| | - Dellamol Sebastian
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
| | - Wei Wei
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
| | - Tashrique A. Khandaker
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
| | - Magdalena R. Andrzejewska
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
| | - Barbara Zajc
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
| | - Mahesh K. Lakshman
- Department of Chemistry and BiochemistryThe City College of New York, 160 Convent Avenue New York, NY 10031 USA
- The Ph.D. Program in ChemistryThe Graduate Center of The City University of New York New York, NY 10016 USA
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Korvinson KA, Akula HK, Malinchak CT, Sebastian D, Wei W, Khandaker TA, Andrzejewska MR, Zajc B, Lakshman MK. Catalytic Reductions Without External Hydrogen Gas: Broad Scope Hydrogenations with Tetrahydroxydiboron and a Tertiary Amine. Adv Synth Catal 2019; 362:166-176. [PMID: 33071705 DOI: 10.1002/adsc.201901099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Facile reduction of aryl halides with a combination of 5% Pd/C, B2(OH)4, and 4-methylmorpholine is reported. Aryl bromides, iodides, and chlorides were efficiently reduced. Aryl dihalides containing two different halogen atoms underwent selective reduction: I over Br and Cl, and Br over Cl. Beyond these, aryl triflates were efficiently reduced. This combination was broadly general, effectuating reductions of benzylic halides and ethers, alkenes, alkynes, aldehydes, and azides, as well as for N-Cbz deprotection. A cyano group was unaffected, but a nitro group and a ketone underwent reduction to a low extent. When B2(OD)4 was used for aryl halide reduction, a significant amount of deuteriation occurred. However, H atom incorporation competed and increased in slower reactions. 4-Methylmorpholine was identified as a possible source of H atoms in this, but a combination of only 4-methylmorpholine and Pd/C did not result in reduction. Hydrogen gas has been observed to form with this reagent combination. Experiments aimed at understanding the chemistry led to the proposal of a plausible mechanism and to the identification of N,N-bis(methyl-d 3)pyridine-4-amine (DMAP-d 6) and B2(OD)4 as an effective combination for full aromatic deuteriation.
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Affiliation(s)
- Kirill A Korvinson
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
| | - Hari K Akula
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA)
| | - Casina T Malinchak
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
| | - Dellamol Sebastian
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
| | - Wei Wei
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
| | - Tashrique A Khandaker
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA)
| | - Magdalena R Andrzejewska
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA)
| | - Barbara Zajc
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031 (USA).,The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016 (USA)
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Khandaker TA, Hess JD, Aguilera R, Andrei G, Snoeck R, Schols D, Pradhan P, Lakshman MK. Synthesis and Evaluations of "1,4-Triazolyl Combretacoumarins" and Desmethoxy Analogues. European J Org Chem 2019; 2019:5610-5623. [PMID: 31579393 PMCID: PMC6774347 DOI: 10.1002/ejoc.201900569] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Indexed: 11/23/2022]
Abstract
1,4-Triazolyl combretacoumarins have been prepared by linking the trimethoxyarene unit of combretastatin A4 with coumarins, via a 1,2,3-triazole. For this, 4-azidocoumarins were accessed by a sequential two-step, one-pot reaction of 4-hydroxycoumarins with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), followed by reaction with NaN3. In the reaction with BOP, a coumarin-derived phosphonium ion intermediate seems to form, leading to an O 4-(benzotriazolyl)coumarin derivative. For the CuAAC reaction of azidocoumarins with 5-ethynyl-1,2,3-trimethoxybenzene, catalytic [(MeCN)4Cu]PF6 in CH2Cl2/MeOH with 2,6-lutidine, at 50 °C, was suitable. The 4-azidocoumarins were less reactive as compared to PhN3 and the NBO coefficients of the azido groups were compared by DFT analysis. Compound solubility was a problem in biological assays. On the basis of the biological and solubility data of one 1,4-triazolyl combretacoumarin, four analogues lacking one or two methoxy groups were synthesized. Reactivity differences among the phenylacetylenes were noted and the NBO coefficients of the alkynes were compared by DFT analysis. In antiproliferative assays, 1-phenyl-4-(3,4,5-trimethoxyphenyl)-1H-1,2,3-triazole showed activity in CEM and MDA-MB-231 cell lines, possibly by apoptosis. The desmethoxy 6-bromo-4-(4-(4-methoxyphenyl)-1H-1,2,3-triazol-1-yl)-2H-chromen-2-one also showed cytotoxicity against the two cell lines, but this did not appear to be consistent with apoptosis. The antiviral activity of the compounds was unremarkable.
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Affiliation(s)
- Tashrique A. Khandaker
- Department of Chemistry and BiochemistryThe City College of New York160 Convent AvenueNew YorkNY10031USA
| | - Jessica D. Hess
- Department of Biological SciencesBorder Biomedical Research CenterThe University of Texas at El PasoEl PasoTX79968USA
| | - Renato Aguilera
- Department of Biological SciencesBorder Biomedical Research CenterThe University of Texas at El PasoEl PasoTX79968USA
| | - Graciela Andrei
- Department of Microbiology and ImmunologyRega Institute of Medical ResearchHerestraat 49 – Box 10433000LeuvenLeuvenBelgium
| | - Robert Snoeck
- Department of Microbiology and ImmunologyRega Institute of Medical ResearchHerestraat 49 – Box 10433000LeuvenLeuvenBelgium
| | - Dominique Schols
- Department of Microbiology and ImmunologyRega Institute of Medical ResearchHerestraat 49 – Box 10433000LeuvenLeuvenBelgium
| | - Padmanava Pradhan
- Department of Chemistry and BiochemistryThe City College of New York160 Convent AvenueNew YorkNY10031USA
| | - Mahesh K. Lakshman
- Department of Chemistry and BiochemistryThe City College of New York160 Convent AvenueNew YorkNY10031USA
- The Ph.D. Program in ChemistryThe Graduate Center of the City University of New YorkNew YorkNY10016USA
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Akula HK, Lakshman MK. Facile Modifications at the C4 Position of Pyrimidine Nucleosides via In Situ Amide Activation with 1H-Benzotriazol-1-yloxy-tris(dimethyl-amino)phosphonium Hexafluorophosphate. ACTA ACUST UNITED AC 2019; 76:e73. [PMID: 30688408 DOI: 10.1002/cpnc.73] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Two approaches for C4 modifications of silyl-protected thymidine, 2'-deoxyuridine, and 3'-azido-2',3'-dideoxythymidine (AZT) are described. In both, nucleoside amide activation with 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and DBU yields O4 -(benzotriazol-1-yl) derivatives. These in situ-formed intermediates are reacted with various nucleophiles, resulting in C4 modifications. In the two-step, one-pot approach, the O4 -(benzotriazol-1-yl) nucleoside intermediates are initially produced by reactions of the nucleosides with BOP and DBU in THF. This step is fast and typically complete within 30 min. Subsequently, the O4 -(benzotriazol-1-yl) derivatives are reacted with nucleophiles, such as aliphatic and aromatic amines, thiols, and alcohols, under appropriate conditions. Workup, isolation, and purification lead to the desired C4-modified pyrimidine nucleosides in good to excellent yields. In the one-step approach, the nucleosides are reacted with BOP and DBU, in the presence of the nucleophile (only aliphatic and aromatic amines, and thiols have been tested). Where comparisons are possible, the one-step approach is generally superior. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- Hari K Akula
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York
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Abstract
There has been increasing use of hypervalent iodine reagents in the field of nucleoside chemistry. Applications span: (a) synthesis of nucleoside analogues with sulfur and seleno sugar surrogates, (b) synthesis of unusual carbocyclic and ether ring-containing nucleosides, (c) introduction of sulfur and selenium into pyrimidine bases of nucleosides and analogues, (d) synthesis of isoxazole and isoxazoline ring-containing nucleoside analogues, (e) involvement of purine ring nitrogen atoms for remote C-H bond oxidation, and (f) metal-catalyzed and uncatalyzed synthesis of benzimidazolyl purine nucleoside analogues by intramolecular C-N bond formation. This review offers a perspective on developments involving the use of hypervalent iodine reagents in the field of nucleoside chemistry that have appeared in the literature in the 2003-2017 time frame.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry & Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA, and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Barbara Zajc
- Department of Chemistry & Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA, and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, NY 10016, USA
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Andrzejewska MR, Vuram PK, Pottabathini N, Gurram V, Relangi SS, Korvinson KA, Doddipalla R, Stahl L, Neary MC, Pradhan P, Sharma S, Lakshman MK. The Disappearing Director: The Case of Directed N-Arylation via a Removable Hydroxyl Group. Adv Synth Catal 2018; 360:2503-2510. [PMID: 30559638 PMCID: PMC6294448 DOI: 10.1002/adsc.201701611] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Indexed: 12/23/2022]
Abstract
A facile and broadly applicable method for the regiospecific N-arylation of benzotriazoles is reported. Copper-mediated reactions of diverse 1-hydroxy-1H-benzotriazoles with aryl boronic acids lead to 1-aryl-1H-benzotriazole 3-oxides. A N1-OH → N3 prototropy in the 1-hydroxy-1H-benzotriazoles is plausibly the underlying basis, where the tautomer is captured by the boronic acid, leading to C-N (not C-O) bond formation. Because the N-O bond in amine N-oxides and 1-hydroxy-1H-benzotriazoles can be easily reduced by diboron reagents such as (pinB)2 and B2(OH)4, exposure of the 1-aryl-1H-benzotriazole 3-oxides to B2(OH)4 then leads to facile reduction of the N-O bond resulting in diverse, regiospecifically-arylated benzotriazoles. Thus, the N-hydroxyl group in 1-hydroxy-1H-benzotriazoles acts as a disposable arylation director.
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Affiliation(s)
- Magdalena R. Andrzejewska
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Prasanna K. Vuram
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Narender Pottabathini
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Venkateshwarlu Gurram
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Siva Subrahmanyam Relangi
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Kirill A. Korvinson
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
- The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
| | - Raju Doddipalla
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Lothar Stahl
- Department of Chemistry, University of North Dakota, 151 Cornell Street Stop 9024, Grand Forks, North Dakota 58202, USA
| | - Michelle C. Neary
- Department of Chemistry, Hunter College, 695 Park Avenue, New York, New York 10065, USA
| | - Padmanava Pradhan
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Somesh Sharma
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Mahesh K. Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
- The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
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16
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Satishkumar S, Poudapally S, Vuram PK, Gurram V, Pottabathini N, Sebastian D, Yang L, Pradhan P, Lakshman MK. Pd-Catalyzed versus Uncatalyzed, PhI(OAc) 2
-Mediated Cyclization Reactions of N
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-([1,1′-Biaryl]-2-yl)Adenine Nucleosides. ChemCatChem 2017. [DOI: 10.1002/cctc.201701686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Sakilam Satishkumar
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Suresh Poudapally
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Prasanna K. Vuram
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Venkateshwarlu Gurram
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Narender Pottabathini
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Dellamol Sebastian
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
- The Ph.D. Program in Chemistry; The Graduate Center of the City University of New York; New York NY 10016 USA
| | - Lijia Yang
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Padmanava Pradhan
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Mahesh K. Lakshman
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
- The Ph.D. Program in Chemistry; The Graduate Center of the City University of New York; New York NY 10016 USA
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Satishkumar S, Poudapally S, Vuram PK, Gurram V, Pottabathini N, Sebastian D, Yang L, Pradhan P, Lakshman MK. Front Cover: Pd-Catalyzed versus Uncatalyzed, PhI(OAc) 2
-Mediated Cyclization Reactions of N
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-([1,1′-Biaryl]-2-yl)Adenine Nucleosides (ChemCatChem 21/2017). ChemCatChem 2017. [DOI: 10.1002/cctc.201701672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sakilam Satishkumar
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Suresh Poudapally
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Prasanna K. Vuram
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Venkateshwarlu Gurram
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Narender Pottabathini
- Discovery Services; GVK Biosciences Pvt. Ltd.; 28A IDA Nacharam Hyderabad 500076 Telangana India
| | - Dellamol Sebastian
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
- The Ph.D. Program in Chemistry; The Graduate Center of the City University of New York; New York NY 10016 USA
| | - Lijia Yang
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Padmanava Pradhan
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
| | - Mahesh K. Lakshman
- Department of Chemistry; The City College of New York; 160 Convent Avenue New York NY 10031 USA
- The Ph.D. Program in Chemistry; The Graduate Center of the City University of New York; New York NY 10016 USA
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18
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Satishkumar S, Poudapally S, Vuram PK, Gurram V, Pottabathini N, Sebastian D, Yang L, Pradhan P, Lakshman MK. Pd-catalyzed versus uncatalyzed, PhI(OAc) 2-mediated cyclization reactions of N6-([1,1'-biaryl]-2-yl)adenine nucleosides. ChemCatChem 2017; 9:4058-4069. [PMID: 29503672 DOI: 10.1002/cctc.201700918] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this work we have assessed reactions of N6-([1,1'-biaryl]-2-yl)adenine nucleosides with Pd(OAc)2 and PhI(OAc)2, via a PdII/PdIV redox cycle. The substrates are readily obtained by Pd/Xantphos-catalyzed reaction of adenine nucleosides with 2-bromo-1,1'-biaryls. In PhMe, the N6-biarylyl nucleosides gave C6-carbazolyl nucleoside analogues by C-N bond formation with the exocyclic N6 nitrogen atom. In the solvent screening for the Pd-catalyzed reactions, an uncatalyzed process was found to be operational. It was observed that the carbazolyl products could also be obtained in the absence of a metal catalyst by reaction with PhI(OAc)2 in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). Thus, under Pd catalysis and in HFIP, reactions proceed to provide carbazolyl nucleoside analogues, with some differences. If reactions of N6-biarylyl nucleoside substrates were conducted in MeCN, formation of aryl benzimidazopurinyl nucleoside derivatives was observed in many cases by C-N bond formation with the N1 ring nitrogen atom of the purine (carbazole and benzimidazole isomers are readily separated by chromatography). Whereas PdII/PdIV redox is responsible for carbazole formation under the metal-catalyzed conditions, in HFIP and MeCN radical cations and/or nitrenium ions can be intermediates. An extensive set of radical inhibition experiments was conducted and the data are presented.
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Affiliation(s)
- Sakilam Satishkumar
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Suresh Poudapally
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Prasanna K Vuram
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Venkateshwarlu Gurram
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Narender Pottabathini
- Discovery Services, GVK Biosciences, Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, Telangana, India
| | - Dellamol Sebastian
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
| | - Lijia Yang
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Padmanava Pradhan
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA
| | - Mahesh K Lakshman
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.,The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
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Lakshman MK, Tine FA, Khandaker TA, Basava V, Agyemang NB, Benavidez MSA, Gaši M, Guerrera L, Zajc B. KHF 2, a mild and selective desilylating agent for phenol t-butyldimethylsilyl (TBDMS) ethers. Synlett 2017; 28:381-385. [PMID: 28713205 DOI: 10.1055/s-0036-1588350] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
TBDMS (t-BuMe2Si, t-butyldimethylsilyl) ethers of a variety of phenols have been deprotected with KHF2 in MeOH, at room temperature. Carboxylic ester and labile phenolic acetate were unaffected under these conditions. In competition reactions between TBDMS ethers of a phenol and two primary benzylic alcohols, the phenolic ether underwent cleavage whereas the alcohol ethers remained intact. From a substrate containing both a phenolic hydroxyl group and a secondary, doubly benzylic hydroxyl group protected as TBDMS ethers, the phenol was rapidly and selectively released. Cleavage of TBDMS, TBDPS, and TIPS ethers of a phenol was also compared. TBDMS and TBDPS ethers underwent cleavage at room temperature within 30 min, whereas removal of the TIPS ether required 2.5 hours. Ease of cleavage appears to be TBDMS ≈ TBDPS > TIPS. At 60 °C, TBDMS ethers of primary benzylic, allylic, and unactivated alcohols can be efficiently desilylated over a prolonged period (13-17 h). Thus, KHF2 proves to be a mild and effective reagent for the selective desilylation of phenol TBDMS ethers at room temperature.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.,The Ph.D. Program in Chemistry, The City University of New York, New York, NY 10016, USA
| | - Fatou A Tine
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Tashrique A Khandaker
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Vikram Basava
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Nana B Agyemang
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Michael S A Benavidez
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Marikone Gaši
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Lisa Guerrera
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Barbara Zajc
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.,The Ph.D. Program in Chemistry, The City University of New York, New York, NY 10016, USA
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Lakshman MK, Vuram PK. Cross-dehydrogenative coupling and oxidative-amination reactions of ethers and alcohols with aromatics and heteroaromatics. Chem Sci 2017; 8:5845-5888. [PMID: 28970941 PMCID: PMC5618789 DOI: 10.1039/c7sc01045a] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/22/2017] [Indexed: 11/21/2022] Open
Abstract
This is a perspective on cross-dehydrogenative coupling reactions of aromatic and heteroaromatic systems with ethers and alcohols via metal or organic catalysis, and through uncatalyzed means, leading to C–C and C–N bond formation.
Cross-dehydrogenative coupling (CDC) is a process in which, typically, a C–C bond is formed at the expense of two C–H bonds, either catalyzed by metals or other organic compounds, or via uncatalyzed processes. In this perspective, we present various modes of C–H bond-activation at sp3 centers adjacent to ether oxygen atoms, followed by C–C bond formation with aromatic systems as well as with heteroaromatic systems. C–N bond-formation with NH-containing heteroaromatics, leading to hemiaminal ethers, is also an event that can occur analogously to C–C bond formation, but at the expense of C–H and N–H bonds. A large variety of hemiaminal ether-forming reactions have recently appeared in the literature and this perspective also includes this complementary chemistry. In addition, the participation of C–H bonds in alcohols in such processes is also described. Facile access to a wide range of compounds can be attained through these processes, rendering such reactions useful for synthetic applications via Csp3 bond activations.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry , The City College of New York , 160 Convent Avenue , New York 10031 , USA . .,The Ph.D. Program in Chemistry , The Graduate Center of The City University of New York , New York 10016 , USA
| | - Prasanna K Vuram
- Department of Chemistry , The City College of New York , 160 Convent Avenue , New York 10031 , USA .
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21
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Satishkumar S, Lakshman MK. Benzimidazopurine nucleosides from N 6-aryl adenosine derivatives by PhI(OAc) 2-mediated C-N bond formation, no metal needed. Chem Commun (Camb) 2017; 53:2226-2229. [PMID: 27976760 DOI: 10.1039/c6cc07722f] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of a variety of N6-aryl 2'-deoxyadenosine and adenosine derivatives with PhI(OAc)2 in 1,1,1,3,3,3-hexafluoro-2-propanol provides a facile access to benzimidazopurine nucleoside analogues by metal-free C-N bond formation with a purinyl nitrogen atom. These reactions likely proceed via radical-cation/radical processes as indicated by radical inhibition experiments.
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Affiliation(s)
- Sakilam Satishkumar
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, NY 10031, USA. and The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, NY 10016, USA
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22
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Akula HK, Kokatla H, Andrei G, Snoeck R, Schols D, Balzarini J, Yang L, Lakshman MK. Facile functionalization at the C4 position of pyrimidine nucleosides via amide group activation with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and biological evaluations of the products. Org Biomol Chem 2017; 15:1130-1139. [PMID: 28054092 PMCID: PMC5367150 DOI: 10.1039/c6ob02334g] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of O-t-butyldimethylsilyl-protected thymidine, 2'-deoxyuridine, and 3'-azidothymidine (AZT) with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) leads to activation of the C4 amide carbonyl by formation of putative O4-(benzotriazol-1-yl) derivatives. Subsequent substitution with alkyl and aryl amines, thiols, and alcohols leads to facile functionalization at this position. Reactions with amines and thiols were conducted either as a two-step, one-pot transformation, or as a one-step conversion. Reactions with alcohols were conducted as two-step, one-pot transformations. In the course of these investigations, the formation of 1-(4-pyrimidinyl)-1H-benzotriazole-3-oxide derivatives from the pyrimidine nucleosides was identified. However, these too underwent conversion to the desired products. Products obtained from AZT were converted to the 3'-amino derivatives by catalytic reduction. All products were assayed for their abilities to inhibit cancer cell proliferation and for antiviral activities. Many were seen to be active against HIV-1 and HIV-2, and one was active against herpes simplex virus-1 (HSV-1).
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Affiliation(s)
- Hari K Akula
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA. and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
| | - Hariprasad Kokatla
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.
| | - Graciela Andrei
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Robert Snoeck
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Dominique Schols
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Jan Balzarini
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Lijia Yang
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA. and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
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23
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Akula HK, Kokatla H, Andrei G, Snoeck R, Schols D, Balzarini J, Yang L, Lakshman MK. Correction: Facile functionalization at the C4 position of pyrimidine nucleosides via amide group activation with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and biological evaluations of the products. Org Biomol Chem 2017; 15:1268. [PMID: 28101554 DOI: 10.1039/c7ob90013a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for 'Facile functionalization at the C4 position of pyrimidine nucleosides via amide group activation with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and biological evaluations of the products' by Hari K. Akula, et al., Org. Biomol. Chem., 2017, DOI: 10.1039/c6ob02334g.
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Affiliation(s)
- Hari K Akula
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA. and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
| | - Hariprasad Kokatla
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.
| | - Graciela Andrei
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Robert Snoeck
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Dominique Schols
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Jan Balzarini
- Laboratory of Virology and Chemotherapy, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, 3000 Leuven, Belgium
| | - Lijia Yang
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.
| | - Mahesh K Lakshman
- Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA. and The Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, USA
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Basava V, Yang L, Pradhan P, Lakshman MK. A novel bis(pinacolato)diboron-mediated N-O bond deoxygenative route to C6 benzotriazolyl purine nucleoside derivatives. Org Biomol Chem 2016; 14:7069-83. [PMID: 27377367 PMCID: PMC4981646 DOI: 10.1039/c6ob01170e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Reaction of amide bonds in t-butyldimethylsilyl-protected inosine, 2'-deoxyinosine, guanosine, 2'-deoxyguanosine, and 2-phenylinosine with commercially available peptide-coupling agents (benzotriazol-1H-yloxy)tris(dimethylaminophosphonium) hexafluorophosphate (BOP), (6-chloro-benzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophosphate (PyClocK), and (7-azabenzotriazol-1H-yloxy)trispyrrolidinophosphonium hexafluorophospate (PyAOP) gave the corresponding O(6)-(benzotriazol-1-yl) nucleoside analogues containing a C-O-N bond. Upon exposure to bis(pinacolato)diboron and base, the O(6)-(benzotriazol-1-yl) and O(6)-(6-chlorobenzotriazol-1-yl) purine nucleoside derivatives obtained from BOP and PyClocK, respectively, underwent N-O bond reduction and C-N bond formation, leading to the corresponding C6 benzotriazolyl purine nucleoside analogues. In contrast, the 7-azabenzotriazolyloxy purine nucleoside derivatives did not undergo efficient deoxygenation, but gave unsymmetrical nucleoside dimers instead. This is consistent with a prior report on the slow reduction of 1-hydroxy-1H-4-aza and 1-hydroxy-1H-7-azabenzotriazoles. Because of the limited number of commercial benzotriazole-based peptide coupling agents, and to show the applicability of the method when such coupling agents are unavailable, 1-hydroxy-1H-5,6-dichlorobenzotriazole was synthesized. Using this compound, silyl-protected inosine and 2'-deoxyinosine were converted to the O(6)-(5,6-dichlorobenzotriazol-1-yl) derivatives via in situ amide activation with PyBroP. The O(6)-(5,6-dichlorobenzotriazol-1-yl) purine nucleosides so obtained also underwent smooth reduction to afford the corresponding C6 5,6-dichlorobenzotriazolyl purine nucleoside derivatives. A total of 13 examples were studied with successful reactions occurring in 11 cases (the azabenzotriazole derivatives, mentioned above, being the only unreactive entities). To understand whether these reactions are intra or intermolecular processes, a crossover experiment was conducted. The results of this experiment as well as those from reactions conducted in the absence of bis(pinacolato)diboron and in the presence of water indicate that detachment of the benzotriazoloxy group from the nucleoside likely occurs, followed by reduction, and reattachment of the ensuing benzotriazole, leading to products.
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Affiliation(s)
- Vikram Basava
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, USA.
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25
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Singh MK, Akula HK, Satishkumar S, Stahl L, Lakshman MK. Ruthenium-Catalyzed C-H Bond Activation Approach to Azolyl Aminals and Hemiaminal Ethers, Mechanistic Evaluations, and Isomer Interconversion. ACS Catal 2016; 6:1921-1928. [PMID: 27563492 DOI: 10.1021/acscatal.5b02603] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C(sp3)-N bond-forming reactions between benzotriazole and 5,6-dimethylbenzotriazole with N-methylpyrrolidinone, tetrahydrofuran, tetrahydropyran, diethyl ether, 1,4-dioxane, and isochroman have been conducted using RuCl3•3H2O/t-BuOOH in 1,2-dichloroethane. In all cases, N1 and N2 alkylation products were obtained, and these are readily separated by chromatography. One of these products, 1-(isochroman-1-yl)-5,6-dimethyl-1H-benzotriazole, was examined by X-ray crystallography. It is the first such compound to be analyzed by this method, and notably, the benzotriazolyl moiety is quasi-axially disposed, consistent with the anomeric effect. This has plausible consequences, not observed previously. In contrast to other hemiaminal ether-forming reactions, which proceed via radicals, this Ru-catalyzed process is not suppressed in the presence of a radical inhibitor. Therefore, an oxoruthenium-species-mediated rapid formation of an oxocarbenium intermediate is believed to occur. In the radical-trapping experiment, previously unknown products containing both the benzotriazole and the TEMPO unit have been identified. In these products, it is likely that the benzotriazole is introduced via a Ru-catalyzed C-N bond formation, whereas C-O bond-formation with TEMPO occurs via a radical reaction. We show that reactions of THF with TEMPO are influenced by ambient light. A competitive reaction of THF and THF-d8 with benzotriazole indicated that C-H bond cleavage occurs ca. 5 times faster than C-D cleavage. This is comparable to other metal-mediated radical reactions of THF, but lower than that observed for a reaction catalyzed by n-Bu4N+I-. Detailed mechanistic experiments and comparisons are described. The catalytic system was also evaluated for reactions of benzimidazole, imidazole, 1,2,4-triazole, and 1,2,3-triazole with THF, and successful reactions were achieved in each case. In the course of our studies, we discovered an unexpected but significant isomerization of some of the benzotriazolyl hemiaminal ethers. This is plausibly attributable to the pseudoaxial orientation of the heterocycle in the products and the stability of oxocarbenium ions, both of which can contribute to C-N bond cleavage and reformation. Predominantly, the N2-isomers rearrange to the N1-isomers even upon storage at low temperature! This previously unknown phenomenon has also been studied and described.
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Affiliation(s)
- Manish K. Singh
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
| | - Hari K. Akula
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
| | - Sakilam Satishkumar
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Lothar Stahl
- Department of Chemistry, The University of North Dakota, 151 Cornell Street Stop 9024, Grand Forks, North Dakota 58202, United States
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College of New York, 160 Convent Avenue, New York, New York 10031, United States
- The Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, New York, New York 10016, United States
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Singh MK, Lakshman MK. Diarylmethanes through an Unprecedented Palladium-Catalyzed C-C Cross-Coupling of 1-(Aryl)methoxy-1 H-Benzotriazoles with Arylboronic Acids. ChemCatChem 2015; 7:4156-4162. [PMID: 27134687 DOI: 10.1002/cctc.201500818] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
1-(Aryl)methoxy-1H-benzotriazoles (ArCH2OBt) are bench-stable reagents that are prepared readily from 1H-benzotriazol-1-yl-4-methylbenzenesulfonate (BtOTs) and benzylic alcohols. These compounds, which contain a N-O-C bond, undergo cross-coupling with arylboronic acids by C-O bond scission with catalysts that comprise Pd(OAc)2 and biarylphosphine ligands. Such reactivity of ArCH2OBt derivatives, leading to diarylmethanes, has not been described previously and constitutes a new activation of benzylic alcohols. With regard to the various ligands-metal complexes that support catalytic activity, it appears that those with smaller "percent buried volumes" (%Vbur) provide better outcomes. This factor has been evaluated in the initial optimization studies and in further reactions with difficult coupling partners. Ligand electronics of the biaryl moiety seem to play a lesser role in this type of reaction. The bis-coordinating bis[(2-diphenylphosphino)phenyl]ether appears to be suitable to improve the yields of low-yielding reactions.
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Affiliation(s)
- Manish K Singh
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031
| | - Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031
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Satishkumar S, Vuram PK, Relangi SS, Gurram V, Zhou H, Kreitman RJ, Martínez Montemayor MM, Yang L, Kaliyaperumal M, Sharma S, Pottabathini N, Lakshman MK. Cladribine Analogues via O⁶-(Benzotriazolyl) Derivatives of Guanine Nucleosides. Molecules 2015; 20:18437-63. [PMID: 26473811 PMCID: PMC4841790 DOI: 10.3390/molecules201018437] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 09/20/2015] [Accepted: 09/22/2015] [Indexed: 11/16/2022] Open
Abstract
Cladribine, 2-chloro-2'-deoxyadenosine, is a highly efficacious, clinically used nucleoside for the treatment of hairy cell leukemia. It is also being evaluated against other lymphoid malignancies and has been a molecule of interest for well over half a century. In continuation of our interest in the amide bond-activation in purine nucleosides via the use of (benzotriazol-1yl-oxy)tris(dimethylamino)phosphonium hexafluorophosphate, we have evaluated the use of O⁶-(benzotriazol-1-yl)-2'-deoxyguanosine as a potential precursor to cladribine and its analogues. These compounds, after appropriate deprotection, were assessed for their biological activities, and the data are presented herein. Against hairy cell leukemia (HCL), T-cell lymphoma (TCL) and chronic lymphocytic leukemia (CLL), cladribine was the most active against all. The bromo analogue of cladribine showed comparable activity to the ribose analogue of cladribine against HCL, but was more active against TCL and CLL. The bromo ribose analogue of cladribine showed activity, but was the least active among the C6-NH₂-containing compounds. Substitution with alkyl groups at the exocyclic amino group appears detrimental to activity, and only the C6 piperidinyl cladribine analogue demonstrated any activity. Against adenocarcinoma MDA-MB-231 cells, cladribine and its ribose analogue were most active.
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Affiliation(s)
- Sakilam Satishkumar
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Prasanna K Vuram
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Siva Subrahmanyam Relangi
- Discovery and Analytical Services, GVK Biosciences Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, India.
| | - Venkateshwarlu Gurram
- Discovery and Analytical Services, GVK Biosciences Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, India.
| | - Hong Zhou
- Clinical Immunotherapy Section, Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Robert J Kreitman
- Clinical Immunotherapy Section, Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | | | - Lijia Yang
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
| | - Muralidharan Kaliyaperumal
- Discovery and Analytical Services, GVK Biosciences Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, India.
| | - Somesh Sharma
- Discovery and Analytical Services, GVK Biosciences Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, India.
| | - Narender Pottabathini
- Discovery and Analytical Services, GVK Biosciences Pvt. Ltd., 28A IDA Nacharam, Hyderabad 500076, India.
| | - Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA.
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Thomson PF, Parrish D, Pradhan P, Lakshman MK. Modular, Metal-Catalyzed Cycloisomerization Approach to Angularly Fused Polycyclic Aromatic Hydrocarbons and Their Oxidized Derivatives. J Org Chem 2015; 80:7435-46. [PMID: 26196673 PMCID: PMC4541800 DOI: 10.1021/acs.joc.5b00931] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Palladium-catalyzed cross-coupling reactions of 2-bromobenzaldehyde and 6-bromo-2,3-dimethoxybenzaldehyde with 4-methyl-1-naphthaleneboronic acid and acenaphthene-5-boronic acid gave corresponding o-naphthyl benzaldehydes. Corey-Fuchs olefination followed by reaction with n-BuLi led to various 1-(2-ethynylphenyl)naphthalenes. Cycloisomerization of individual 1-(2-ethynylphenyl)naphthalenes to various benzo[c]phenanthrene (BcPh) analogues was accomplished smoothly with catalytic PtCl2 in PhMe. In the case of 4,5-dihydrobenzo[l]acephenanthrylene, oxidation with DDQ gave benzo[l]acephenanthrylene. The dimethoxy-substituted benzo[c]phenanthrenes were demethylated with BBr3 and oxidized to the o-quinones with PDC. Reduction of these quinones with NaBH4 in THF/EtOH in an oxygen atmosphere gave the respective dihydrodiols. Exposure of the dihydrodiols to N-bromoacetamide in THF-H2O led to bromohydrins that were cyclized with Amberlite IRA 400 HO(-) to yield the series 1 diol epoxides. Epoxidation of the dihydrodiols with mCPBA gave the isomeric series 2 diol epoxides. All of the hydrocarbons as well as the methoxy-substituted ones were crystallized and analyzed by X-ray crystallography, and these data are compared to other previously studied BcPh derivatives. The methodology described is highly modular and can be utilized for the synthesis of a wide variety of angularly fused polycyclic aromatic hydrocarbons and their putative metabolites and/or other derivatives.
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Affiliation(s)
- Paul F. Thomson
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Damon Parrish
- Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington D.C. 20375, United States
| | - Padmanava Pradhan
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, United States
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, United States
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Gurram V, Akula HK, Garlapati R, Pottabathini N, Lakshman MK. Mild and General Access to Diverse 1 H-Benzotriazoles via Diboron-Mediated N-OH Deoxygenation and Palladium-Catalyzed C-C and C-N Bond Formation. Adv Synth Catal 2015; 357:451-462. [PMID: 25729343 PMCID: PMC4340595 DOI: 10.1002/adsc.201400889] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Benzotriazoles are a highly important class of compounds with broad-ranging applications in such diverse areas as medicinal chemistry, as auxiliaries in organic synthesis, in metallurgical applications, in aircraft deicing and brake fluids, and as antifog agents in photography. Although there are numerous approaches to N-substituted benzotriazoles, the essentially one general method to N-unsubstituted benzotriazoles is via diazotization of o-phenylenediamines, which can be limited by the availability of suitable precursors. Other methods to N-unsubstitued benzotriazoles are quite specialized. Although reduction of 1-hydroxy-1H-benzotriazoles is known the reactions are not particularly convenient or broadly applicable. This presents a limitation for easy access to and availability of diverse benzotriazoles. Herein, we demonstrate a new, broadly applicable method to diverse 1H-benzotriazoles via a mild diboron-reagent mediated deoxygenation of 1-hydroxy-1H-benzotriazoles. We have also evaluated sequential deoxygenation and Pd-mediated C-C and C-N bond formation as a one-pot process for further diversification of the benzotriazole moiety. However, results indicated that purification of the deoxygenation product prior to the Pd-mediated reaction is critical to the success of such reactions. The overall chemistry allows for facile access to a variety of new benzotriazoles. Along with the several examples presented, a discussion of the advantages of the approaches is described, as also a possible mechanism for the deoxygenation process.
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Affiliation(s)
- Venkateshwarlu Gurram
- Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA
Nacharam Hyderabad 500076, Andhra Pradesh, India
| | - Hari K. Akula
- Department of Chemistry The City College and The City
University of New York 160 Convent Avenue New York, NY 10031, USA
| | - Ramesh Garlapati
- Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA
Nacharam Hyderabad 500076, Andhra Pradesh, India
| | - Narender Pottabathini
- Discovery Services, GVK Biosciences Pvt. Ltd. 28A, IDA
Nacharam Hyderabad 500076, Andhra Pradesh, India
| | - Mahesh K. Lakshman
- Department of Chemistry The City College and The City
University of New York 160 Convent Avenue New York, NY 10031, USA
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Yedulla VR, Pradhan P, Yang L, Lakshman MK. Cycloaddition of Arynes and Cyclic Enol Ethers as a Platform for Access to Stereochemically Defined 1,2-Disubstituted Benzocyclobutenes. European J Org Chem 2015; 2015:750-764. [PMID: 27642260 PMCID: PMC5026328 DOI: 10.1002/ejoc.201403250] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Indexed: 11/06/2022]
Abstract
Benzocyclobutenes (BCBs) are important entities in a multitude of areas, such as complex organic synthesis, materials and polymer chemistry, and electronics. Whereas reactions between arynes and ketene acetals have been well studied, reactions with cyclic enol ethers are unknown. A cis olefin geometry in cyclic enol ethers makes them well suited for formal [2 + 2] cycloaddition with arynes than for competing ene reactions, making them effective reactants. Reactions of 2,3-dihydrofuran, 2,3-dihydro-3H-pyran, 5-butyl-2,3-dihydrofuran, (S)-2-((benzyloxy)methyl)-2,3-dihydrofuran, and 1,4-dioxene with various arynes were successful. An advantage of the use of cyclic enol ethers is that despite the plausible intermediacy of zwitterionic intermediates, the products are limited to a cis ring junction. This can be exploited for potential access to stereochemically-defined 1,2-disubstituted BCBs. As a demonstration, ether ring cleavage with BBr3 provided trans-functionalized BCBs and displacement with azide then provided cis derivatives. DFT computations have been utilized to understand the structures of three arynes in relation to the cycloadditions and for a predictive evaluation of product ratios in two cases. A comparative evaluation of the HOMO energies of a related series of cyclic olefins has also been performed by DFT computations.
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Affiliation(s)
- Vijayendar R. Yedulla
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Padmanava Pradhan
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Lijia Yang
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
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31
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Lakshman MK, Singh MK, Kumar M, Chamala RR, Yedulla VR, Wagner D, Leung E, Yang L, Matin A, Ahmad S. Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications. Beilstein J Org Chem 2014; 10:1919-32. [PMID: 25246951 PMCID: PMC4168895 DOI: 10.3762/bjoc.10.200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/10/2014] [Indexed: 11/24/2022] Open
Abstract
(1H-Benzo[d][1,2,3]triazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), 1H-benzo[d][1,2,3]triazol-1-yl 4-methylbenzenesulfonate (Bt-OTs), and 3H-[1,2,3]triazolo[4,5-b]pyridine-3-yl 4-methylbenzenesulfonate (At-OTs) are classically utilized in peptide synthesis for amide-bond formation. However, a previously undescribed reaction of these compounds with alcohols in the presence of a base, leads to 1-alkoxy-1H-benzo- (Bt-OR) and 7-azabenzotriazoles (At-OR). Although BOP undergoes reactions with alcohols to furnish 1-alkoxy-1H-benzotriazoles, Bt-OTs proved to be superior. Both, primary and secondary alcohols undergo reaction under generally mild reaction conditions. Correspondingly, 1-alkoxy-1H-7-azabenzotriazoles were synthesized from At-OTs. Mechanistically, there are three pathways by which these peptide-coupling agents can react with alcohols. From (31)P{(1)H}, [(18)O]-labeling, and other chemical experiments, phosphonium and tosylate derivatives of alcohols seem to be intermediates. These then react with BtO(-) and AtO(-) produced in situ. In order to demonstrate broader utility, this novel reaction has been used to prepare a series of acyclic nucleoside-like compounds. Because BtO(-) is a nucleofuge, several Bt-OCH2Ar substrates have been evaluated in nucleophilic substitution reactions. Finally, the possible formation of Pd π-allyl complexes by departure of BtO(-) has been queried. Thus, alpha-allylation of three cyclic ketones was evaluated with 1-(cinnamyloxy)-1H-benzo[d][1,2,3]triazole, via in situ formation of pyrrolidine enamines and Pd catalysis.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Manish K Singh
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Mukesh Kumar
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Raghu Ram Chamala
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Vijayender R Yedulla
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Domenick Wagner
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Evan Leung
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Lijia Yang
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Asha Matin
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
| | - Sadia Ahmad
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
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Chamala RR, Parrish D, Pradhan P, Lakshman MK. Purinyl N1-directed aromatic C-H oxidation in 6-arylpurines and 6-arylpurine nucleosides. J Org Chem 2013; 78:7423-35. [PMID: 23844876 DOI: 10.1021/jo4008282] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Palladium-catalyzed C-H bond activation and oxidation of C6 arylpurines as well as C6 arylpurine nucleosides can be accomplished using Pd(OAc)2/PhI(OAc)2 in CH3CN. Despite the presence of four nitrogen atoms in the purine moiety as well as the polyoxygenated saccharide and a labile glycosidic bond in the nucleosides, these reactions can be effectively conducted. Notably, the generally more labile 2'-deoxyribonucleosides also undergo reaction. The reaction conditions can be tuned to yield either monoacetoxylated or diacetoxylated products predominantly. In the course of these investigations, a dimeric Pd(II)-containing cyclopalladated C6 naphthylpurine derivative has been obtained and crystallographically characterized. This compound is competent in catalyzing the oxidization with PhI(OAc)2, indicating its plausible intermediacy in the chemistry. The X-ray structure of a monoacetoxylated product from this reaction has also been obtained.
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Affiliation(s)
- Raghu Ram Chamala
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, USA
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Abstract
The copper-catalyzed azide-alkyne cycloaddition (CuAAC) is a highly effective method for the selective incorporation of deuterium atom into the C-5 position of the 1,2,3-triazole structure. Reactions of alkynes and azides can be conveniently carried out in a biphasic medium of CH(2)Cl(2)/D(2)O, using the CuSO(4)/Na ascorbate system. The mildness of the method renders it applicable to substrates of relatively high complexity, such as nucleosides. Good yields and high levels of deuterium incorporation were observed. A reaction conducted in equimolar H(2)O and D(2)O showed 2.7 times greater incorporation of hydrogen atom as compared to deuterium. This is consistent with the H(+) and D(+) ion concentrations in H(2)O and D(2)O, respectively. With appropriately deuterated precursors, partially to fully deuterated triazoles were assembled where the final deuterium atom was incorporated in the triazole-forming step.
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Affiliation(s)
- Hari K. Akula
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031-9198
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031-9198
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Gurram V, Pottabathini N, Garlapati R, Chaudhary AB, Patro B, Lakshman MK. C-C cross-coupling reactions of O6-alkyl-2-haloinosine derivatives and a one-pot cross-coupling/O6-deprotection procedure. Chem Asian J 2012; 7:1853-61. [PMID: 22570232 PMCID: PMC3518038 DOI: 10.1002/asia.201200093] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Indexed: 11/11/2022]
Abstract
Reaction conditions for the CC cross-coupling of O(6)-alkyl-2-bromo- and 2-chloroinosine derivatives with aryl-, hetaryl-, and alkylboronic acids were studied. Optimization experiments with silyl-protected 2-bromo-O(6)-methylinosine led to the identification of [PdCl(2)(dcpf)]/K(3)PO(4) in 1,4-dioxane as the best conditions for these reactions (dcpf=1,1'-bis(dicyclohexylphosphino)ferrocene). Attempted O(6)-demethylation, as well as the replacement of the C-6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd-cleavable groups such that C-C cross-coupling and O(6)-deprotection could be accomplished in a single step. Thus, inosine 2-chloro-O(6)-allylinosine was chosen as the substrate and, after re-evaluation of the cross-coupling conditions with 2-chloro-O(6)-methylinosine as a model substrate, one-step C-C cross-coupling/deprotection reactions were performed with the O(6)-allyl analogue. These reactions are the first such examples of a one-pot procedure for the modification and deprotection of purine nucleosides under C-C cross-coupling conditions.
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Affiliation(s)
- Venkateshwarlu Gurram
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd., 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh, India
- Jawaharlal Nehru Technological University, Kukatpally, Hyderabad 500085, Andhra Pradesh, India
| | - Narender Pottabathini
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd., 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh, India
| | - Ramesh Garlapati
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd., 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh, India
| | - Avinash B. Chaudhary
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd., 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh, India
| | - Balaram Patro
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd., 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh, India
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031, USA
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35
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Gurram V, Pottabathini N, Garlapati R, Chaudhary AB, Patro B, Lakshman MK. Cover Picture: CC Cross‐Coupling Reactions of
O
6
‐Alkyl‐2‐Haloinosine Derivatives and a One‐Pot Cross‐Coupling/
O
6
‐Deprotection Procedure (Chem. Asian J. 8/2012). Chem Asian J 2012. [DOI: 10.1002/asia.201290030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Venkateshwarlu Gurram
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh (India), Fax: (+91) 40 66281505
- Jawaharlal Nehru Technological University, Kukatpally, Hyderabad 500085, Andhra Pradesh (India)
| | - Narender Pottabathini
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh (India), Fax: (+91) 40 66281505
| | - Ramesh Garlapati
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh (India), Fax: (+91) 40 66281505
| | - Avinash B. Chaudhary
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh (India), Fax: (+91) 40 66281505
| | - Balaram Patro
- Medicinal and Analytical Chemistry Divisions, GVK Biosciences Pvt. Ltd. 28A, IDA Nacharam, Hyderabad 500076, Andhra Pradesh (India), Fax: (+91) 40 66281505
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031 (USA), Fax: (+1) 212‐650‐6107
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Lakshman MK, Kumar A, Balachandran R, Day BW, Andrei G, Snoeck R, Balzarini J. Synthesis and biological properties of C-2 triazolylinosine derivatives. J Org Chem 2012; 77:5870-83. [PMID: 22758929 DOI: 10.1021/jo300628y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
O(6)-(Benzotriazol-1H-yl)guanosine and its 2'-deoxy analogue are readily converted to the O(6)-allyl derivatives that upon diazotization with t-BuONO and TMS-N(3) yield the C-2 azido derivatives. We have previously analyzed the solvent-dependent azide·tetrazole equilibrium of C-6 azidopurine nucleosides, and in contrast to these, the O(6)-allyl C-2 azido nucleosides appear to exist predominantly in the azido form, relatively independent of solvent polarity. In the presently described cases, the tetrazole appears to be very minor. Consistent with the presence of the azido functionality, each neat C-2 azide displayed a prominent IR band at 2126-2130 cm(-1). A screen of conditions for the ligation of the azido nucleosides with alkynes showed that CuCl in t-BuOH/H(2)O is optimal, yielding C-2 1,2,3-triazolyl nucleosides in 70-82% yields. Removal of the silyl groups with Et(3)N·3HF followed by deallylation with PhSO(2)Na/Pd(PPh(3))(4) gave the C-2 triazolylinosine nucleosides. In a continued demonstration of the versatility of O(6)-(benzotriazol-1H-yl)purine nucleosides, one C-2 triazolylinosine derivative was converted to two adenosine analogues via these intermediates, under mild conditions. Products were desilylated for biological assays. The two C-2 triazolyl adenosine analogues demonstrated pronounced antiproliferative activity in human ovarian and colorectal carcinoma cell cultures. When evaluated for antiviral activity against a broad spectrum of DNA and RNA viruses, some of the C-2 triazolylinosine derivatives showed modest inhibitory activity against cytomegalovirus.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, USA.
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Kokatla HP, Lakshman MK. Two-step, one-pot synthesis of inosine, guanosine, and 2'-deoxyguanosine O6-ethers via intermediate O6-(benzotriazol-1-yl) derivatives. Curr Protoc Nucleic Acid Chem 2012; Chapter 1:Unit1.26. [PMID: 22700333 DOI: 10.1002/0471142700.nc0126s49] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A simple method for the etherification at the O(6)-position of silyl-protected inosine, guanosine, and 2'-deoxyguanosine is described. Typically, a THF solution of the silylated nucleoside is treated with 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and Cs(2)CO(3) under a nitrogen atmosphere. Conversion to the O(6)-(benzotriazol-1-yl) ethers occurs within about 10 min for inosine, and within about 60 min for guanosine and 2'-deoxyguanosine. Then, for reaction with alcohols, the reaction mixture is evaporated and the O(6)-(benzotriazol-1-yl) ether is treated with Cs(2)CO(3) and an appropriate alcohol, at room temperature. On the other hand, for reaction with phenols, Cs(2)CO(3) and the appropriate phenol are added to the reaction mixture without evaporation, and the reaction is carried out at 70°C. Subsequently, workup, isolation, and purification lead to the requisite O(6)-alkyl or O(6)-aryl ethers in good to excellent yields.
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Affiliation(s)
- Hari Prasad Kokatla
- The City College and The City University of New York, New York City, NY, USA
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Lakshman MK, Deb AC, Chamala RR, Pradhan P, Pratap R. Inside Cover: Direct Arylation of 6-Phenylpurine and 6-Arylpurine Nucleosides by Ruthenium-Catalyzed CH Bond Activation (Angew. Chem. Int. Ed. 48/2011). Angew Chem Int Ed Engl 2011. [DOI: 10.1002/anie.201106047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lakshman MK, Deb AC, Chamala RR, Pradhan P, Pratap R. Innentitelbild: Direct Arylation of 6-Phenylpurine and 6-Arylpurine Nucleosides by Ruthenium-Catalyzed CH Bond Activation (Angew. Chem. 48/2011). Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201106047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lakshman MK, Deb AC, Chamala RR, Pradhan P, Pratap R. Direct arylation of 6-phenylpurine and 6-arylpurine nucleosides by ruthenium-catalyzed C-H bond activation. Angew Chem Int Ed Engl 2011; 50:11400-4. [PMID: 21956882 DOI: 10.1002/anie.201104035] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Indexed: 11/06/2022]
Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, New York, NY 10031-9198, USA.
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Lakshman MK, Deb AC, Chamala RR, Pradhan P, Pratap R. Direct Arylation of 6-Phenylpurine and 6-Arylpurine Nucleosides by Ruthenium-Catalyzed CH Bond Activation. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201104035] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)(2) and (catB)(2), respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N'-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)(2) was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)(2), triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)(2) has been probed by (1)H and (11)B NMR.
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Affiliation(s)
- Hari Prasad Kokatla
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031-9198, United States
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Lagisetty P, Zhang L, Lakshman MK. Corrigendum: Simple Methodology for Heck Arylation at C-8 of Adenine Nucleosides. Adv Synth Catal 2011. [DOI: 10.1002/adsc.201190004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
A one-pot synthesis of ethers derived from inosine, guanosine, 2'-deoxyguanosine, and pyrimidinones is described. Exposure of the heterocycle to 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and Cs(2)CO(3) produces a reactive intermediate, which is converted to the desired ether by subsequent addition of an appropriate alcohol or phenol and Cs(2)CO(3). Although rapid formation of HMPA from BOP can occur in the presence of an alcohol and base, as demonstrated by the reaction with methanol, under appropriate conditions these heteroaryl ethers can be efficiently synthesized.
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Affiliation(s)
- Hari Prasad Kokatla
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031-9198, USA
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Thomson PF, Lagisetty P, Balzarini J, De Clercq E, Lakshman MK. Palladium-Catalyzed Aryl Amination Reactions of 6-Bromo- and 6-Chloropurine Nucleosides. Adv Synth Catal 2010; 352:1728-1735. [PMID: 21818182 PMCID: PMC3148652 DOI: 10.1002/adsc.200900728] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Palladium‐catalyzed C—N bond forming reactions of 6‐bromo‐ as well as 6‐chloropurine ribonucleosides and the 2′‐deoxy analogues with arylamines are described. Efficient conversions were observed with palladium(II) acetate/Xantphos/cesium carbonate, in toluene at 100 °C. Reactions of the bromonucleoside derivatives could be conducted at a lowered catalytic loading [5 mol% Pd(OAc)2/7.5 mol% Xantphos], whereas good product yields were obtained with a higher catalyst load [10 mol% Pd(OAc)2/15 mol% Xantphos] when the chloro analogue was employed. Among the examples evaluated, silyl protection for the hydroxy groups appears better as compared to acetyl. The methodology has been evaluated via reactions with a variety of arylamines and by synthesis of biologically relevant deoxyadenosine and adenosine dimers. This is the first detailed analysis of aryl amination reactions of 6‐chloropurine nucleosides, and comparison of the two halogenated nucleoside substrates.
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Affiliation(s)
- Paul F Thomson
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, U.S.A
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Lakshman MK, Singh MK, Parrish D, Balachandran R, Day BW. Azide-tetrazole equilibrium of C-6 azidopurine nucleosides and their ligation reactions with alkynes. J Org Chem 2010; 75:2461-73. [PMID: 20297785 DOI: 10.1021/jo902342z] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Facile syntheses of C-6 azidopurine ribonucleosides and 2'-deoxyribonucleosides have been developed. For silyl- and acetyl-protected as well as unprotected nucleosides, access to the azido derivatives could be readily attained via displacement of BtO(-) from the O(6)-(benzotriazol-1-yl)inosine nucleosides by azide anion. Use of diphenylphosphoryl azide/DBU as a simple route to the acetyl-protected azido nucleosides was also evaluated, but this proved to be inferior. Since these azido nucleosides can exist in an azide.tetrazole equilibrium, the effect of solvent polarity on this equilibrium was investigated. Subsequently, a detailed analysis of Cu-mediated azide-alkyne ("click") ligation was undertaken. Biphasic CH(2)Cl(2)/H(2)O medium proved to be best for the ligation reactions, suppressing the undesired azide reduction that was competing. Interestingly, although the tetrazolyl isomer predominates (ca. 80%) in CD(2)Cl(2) and in CD(2)Cl(2)/D(2)O, the Cu-catalyzed click reactions proceed smoothly with the silyl-protected ribo- and 2'-deoxyribonucleosides, leading to the C-6 triazolyl products in good to excellent yields. Thus, depletion of the azido form from the reaction mixture shifts the azide.tetrazole equilibrium, eventually resulting in complete consumption of azide and tetrazole. In several cases, major and minor azide-alkyne ligation products were observed, and characterization data are provided for both. In order to confirm the regiochemistry leading to the major isomer, one product was crystallized and evaluated by X-ray crystallography. The Cu-catalyzed azide-alkyne ligation is clearly efficient and significantly superior to thermal reactions, which were slow. Biological evaluation showed low cytotoxicities for the agents, suggesting their usefulness as biological probes.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, USA.
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Abstract
The combination of PPh3/I2 has been shown to be effective for conversion of a range of carboxylic acids to 2°, 3°, and Weinreb amides. Simplification of the procedure was possible with the use of polymer-supported PPh3/I2. Weinreb amides produced via the use of polymer-supported PPh3 could be filtered through a short silica gel plug and used in further transformations. Thus, use of polymer-supported PPh3 offers potential applicability to diversity-oriented reactions. Formal total syntheses of apocynin and pratosine, as well as syntheses of anhydrolychorinone and hippadine, have been achieved via the use of this amide-forming method. An attempt has been made to gain insight into this reaction.
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Affiliation(s)
- Amit Kumar
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031-9198, U.S.A
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Bae S, Lakshman MK. A Novel Polymer Supported Approach to Nucleoside Modification. J Org Chem 2009. [DOI: 10.1021/jo901489r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Pratap R, Parrish D, Gunda P, Venkataraman D, Lakshman MK. Influence of Biaryl Phosphine Structure on C−N and C−C Bond Formation. J Am Chem Soc 2009; 131:12240-9. [DOI: 10.1021/ja902679b] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ramendra Pratap
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Damon Parrish
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Padmaja Gunda
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - D. Venkataraman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, Massachusetts 01003
| | - Mahesh K. Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, New York 10031, Naval Research Laboratory, Code 6030, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, Massachusetts 01003
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Abstract
A facile method for the introduction of various substituents at the C-6 position of guanosine and 2'-deoxyguanosine is reported. In a simple, 1-step transformation, tert-butyldimethylsilyl protected guanosine and 2'-deoxyguanosine were converted to the O(6)-(benzotriazol-1-yl) derivatives via reaction with 1H-benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) and 1,8-diazabicyclo[5.4.0]undec-7ene (DBU). The easily isolated, stable and storable, O(6)-(benzotriazol-1-yl) guanosine derivatives upon exposure to a range of nucleophiles, under appropriate conditions, led to the C-6 modified 2-amino purine nucleoside analogues in good yields.
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Affiliation(s)
- Mahesh K Lakshman
- Department of Chemistry, The City College and The City University of New York, 160 Convent Avenue, New York, NY 10031-9198, USA.
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