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Huang X, Xiong R, Yi C, Bai M, Tang Y, Xu S, Li Y. A Radical Precursor Based on the Aromatization of p-Quinol Esters Enabled by Pyridine-Boryl Radical. J Org Chem 2025; 90:3093-3100. [PMID: 39948718 DOI: 10.1021/acs.joc.4c02831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2025]
Abstract
A class of prearomatic carboxylic acid p-quinol ester radical precursors has been developed successfully, which could undergo homolytic cleavage of the para C-O bond of p-quinol esters via pyridine-boryl radical-induced aromatization in the presence of pyridines and diboron reagents, affording the corresponding alkyl radical via decarboxylation from the carboxyl radical in situ. In addition, the prearomatic radical precursors were further applied in radical substitution with phenylsulfonyl compounds and radical self-coulpings. This method not only provides a new approach to the generation of a radical intermediate but also expands the application of boron radicals.
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Affiliation(s)
- Xiaoli Huang
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
- Shanxi Beihua Guanlv Chemical Co., LTD, Shanxi Yongji 044500, P. R. China
| | - Ruji Xiong
- School of Pharmacy, Health Science Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Cui Yi
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Meiqi Bai
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Yuhai Tang
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Silong Xu
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Yang Li
- Department of Material Chemistry, School of Chemistry, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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Trojan M, Kučnirová K, Bouzková Š, Cvačka J, Čejka J, Tavčar G, Rybáčková M, Kvíčala J. Quaternary ammonium fluorides and difluorosilicates as nucleophilic fluorination reagents. Org Biomol Chem 2024; 22:1047-1056. [PMID: 38197465 DOI: 10.1039/d3ob01875j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
TBAT (tetrabutylammonium difluorotriphenylsilicate) is an excellent homogeneous nucleophilic fluorination reagent, but a high excess of the reagent was reported to be essential. We hence optimized the reaction conditions and compared its nucleophilic fluorination reactivity with that of other common commercial nucleophilic fluorination reagents, such as anhydrous TBAF and TASF (tris(dimethylamino)sulfonium difluorotrimethylsilicate). As the substrates, we employed a standard set of primary and secondary octyl substrates under identical conditions. To eliminate the possibility of hydrogen fluoride elimination in the above reagents, we prepared four quaternary ammonium fluorides lacking β-elimination possibility in the hydrocarbon chain, transformed them to the corresponding difluorotriphenylsilicates, and compared their reactivity with that of the commercial reagents. Furthermore, attempts to isolate analogous tetrabutylammonium difluoromethyldiphenylsilicate or difluorodimethylphenylsilicate failed, as was confirmed by comparison of the published experimental data with computed 19F NMR spectra. Finally, we studied the transition states of decomposition of various tetramethylammonium methylphenyldifluorosilicates by DFT methods and found that their relative energies increase with an increasing number of phenyl groups. The formation of difluorosilicates is a nearly barrierless process.
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Affiliation(s)
- Michal Trojan
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
| | - Kateřina Kučnirová
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
| | - Šárka Bouzková
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
| | - Josef Cvačka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 542/2, 160 00 Prague 6, Czech Republic
| | - Jan Čejka
- Department of Solid State Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Gašper Tavčar
- Department of Inorganic Chemistry and Technology, "Jožef Stefan" Institute, Jamova cesta 39, Ljubljana, Slovenia
| | - Markéta Rybáčková
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
| | - Jaroslav Kvíčala
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
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Kirkeby EK, Schwartz ZT, Lovasz MA, Roberts AG. Deaminative ring contraction for the synthesis of polycyclic heteroaromatics: a concise total synthesis of toddaquinoline. Chem Sci 2023; 14:10508-10514. [PMID: 37800000 PMCID: PMC10548534 DOI: 10.1039/d3sc03936f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 09/07/2023] [Indexed: 10/07/2023] Open
Abstract
A concise strategy to prepare polycyclic heteroaromatics involving a deaminative contraction cascade is detailed. The efficient deaminative ring contraction involves the in situ methylation of a biaryl-linked dihydroazepine to form a cyclic ammonium cation that undergoes a base-induced [1,2]-Stevens rearrangement/dehydroamination sequence. The presence of pseudosymmetry guides the retrosynthetic analysis of pyridyl-containing polycyclic heteroaromatics, enabling their construction by the reductive cyclization and deaminative contraction of tertiary amine precursors.
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Affiliation(s)
- Emily K Kirkeby
- Department of Chemistry, University of Utah 315 South 1400 East Salt Lake City Utah 84112 USA
| | - Zachary T Schwartz
- Department of Chemistry, University of Utah 315 South 1400 East Salt Lake City Utah 84112 USA
| | - Myles A Lovasz
- Department of Chemistry, University of Utah 315 South 1400 East Salt Lake City Utah 84112 USA
| | - Andrew G Roberts
- Department of Chemistry, University of Utah 315 South 1400 East Salt Lake City Utah 84112 USA
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Shimazumi R, Tanimoto R, Tobisu M. Nickel/Photoredox Dual-Catalyzed Conversion of Allyl Esters to Ketones via the Formal Deletion of Oxygen. Org Lett 2023; 25:6440-6445. [PMID: 37594903 DOI: 10.1021/acs.orglett.3c02606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
We report herein the catalytic conversion of allylic esters into the corresponding ketones by the formal deletion of an oxygen atom. The key to the success of the reaction is the dual use of nickel and photoredox catalysts; the former mediates C-O bond activation and C-C bond formation, while the latter is responsible for deoxygenation of the acyloxy group using PPh3 as a stoichiometric reductant. Catalytic replacement of an oxygen atom of an allyl ester with a tethered alkene is also accomplished.
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Affiliation(s)
- Ryoma Shimazumi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Riku Tanimoto
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
| | - Mamoru Tobisu
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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McFadden TP, Nwachukwu CI, Roberts AG. An amine template strategy to construct successive C-C bonds: synthesis of benzo[ h]quinolines by a deaminative ring contraction cascade. Org Biomol Chem 2022; 20:1379-1385. [PMID: 35084425 PMCID: PMC8957836 DOI: 10.1039/d1ob02245h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We developed a convergent strategy to build, cyclize and excise nitrogen from tertiary amines for the synthesis of polyheterocyclic aromatics. Biaryl-linked azepine intermediates can undergo a deaminative ring contraction cascade reaction, excising nitrogen with the formation of an aromatic core. This strategy and deaminative ring contraction reaction are useful for the synthesis of benzo[h]quinolines.
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Affiliation(s)
- Timothy Patrick McFadden
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.
| | | | - Andrew George Roberts
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.
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Cp*Ir complex bearing a flexible bridging and functional 2,2′-methylenebibenzimidazole ligand as an auto-tandem catalyst for the synthesis of N-methyl tertiary amines from imines via transfer hydrogenation/N-methylation with methanol. J Catal 2021. [DOI: 10.1016/j.jcat.2021.08.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Shu XZ, Pan FF, Guo P, Huang X. Synthesis of Dibenzyls by Nickel-Catalyzed Homocoupling of Benzyl Alcohols. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/a-1467-2432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractDibenzyls are essential building blocks that are widely used in organic synthesis, and they are typically prepared by the homocoupling of halides, organometallics, and ethers. Herein, we report an approach to this class of compounds using alcohols, which are more stable and readily available. The reaction proceeds via nickel-catalyzed and dimethyl oxalate assisted dynamic kinetic homocoupling of benzyl alcohols. Both primary and secondary alcohols are tolerated.
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Affiliation(s)
- Xing-Zhong Shu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University
| | - Feng-Feng Pan
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University
- College of Chemical Engineering and Technology, Tianshui Normal University
| | - Peng Guo
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University
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Kennedy SH, Dherange BD, Berger KJ, Levin MD. Skeletal editing through direct nitrogen deletion of secondary amines. Nature 2021; 593:223-227. [PMID: 33981048 DOI: 10.1038/s41586-021-03448-9] [Citation(s) in RCA: 166] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/11/2021] [Indexed: 11/09/2022]
Abstract
Synthetic chemistry aims to build up molecular complexity from simple feedstocks1. However, the ability to exert precise changes that manipulate the connectivity of the molecular skeleton itself remains limited, despite possessing substantial potential to expand the accessible chemical space2,3. Here we report a reaction that 'deletes' nitrogen from organic molecules. We show that N-pivaloyloxy-N-alkoxyamides, a subclass of anomeric amides, promote the intermolecular activation of secondary aliphatic amines to yield intramolecular carbon-carbon coupling products. Mechanistic experiments indicate that the reactions proceed via isodiazene intermediates that extrude the nitrogen atom as dinitrogen, producing short-lived diradicals that rapidly couple to form the new carbon-carbon bond. The reaction shows broad functional-group tolerance, which enables the translation of routine amine synthesis protocols into a strategy for carbon-carbon bond constructions and ring syntheses. This is highlighted by the use of this reaction in the syntheses and skeletal editing of bioactive compounds.
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Affiliation(s)
- Sean H Kennedy
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Balu D Dherange
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | | | - Mark D Levin
- Department of Chemistry, University of Chicago, Chicago, IL, USA.
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Liu J, Yang Y, Ouyang K, Zhang WX. Transition-metal-catalyzed transformations of C–N single bonds: Advances in the last five years, challenges and prospects. GREEN SYNTHESIS AND CATALYSIS 2021. [DOI: 10.1016/j.gresc.2021.04.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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