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Noji M, Baba M, Hirabe R, Hayashi S, Takanami T. Proton-accelerated Lewis acid catalysis for stereo- and regioselective isomerization of epoxides to allylic alcohols. Chem Commun (Camb) 2021; 57:7104-7107. [PMID: 34179905 DOI: 10.1039/d1cc02840e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The isomerization of epoxides to allylic alcohols was developed via proton-accelerated Lewis acid catalysis. The addition of tBuOH as a proton source is the key to the efficient catalytic cycle. Trisubstituted epoxides, including enantioenriched derivatives, were selectively converted to secondary-allylic alcohols without loss of enantiopurity.
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Affiliation(s)
- Masahiro Noji
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
| | - Misako Baba
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
| | - Rina Hirabe
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
| | - Satoshi Hayashi
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
| | - Toshikatsu Takanami
- Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan.
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Igawa K, Yoshihiro D, Abe Y, Tomooka K. Enantioselective Synthesis of Silacyclopentanes. Angew Chem Int Ed Engl 2016; 55:5814-8. [PMID: 27037672 DOI: 10.1002/anie.201511728] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 11/10/2022]
Abstract
A variety of functionalized silacyclopentanes were synthesized by highly enantioselective β-eliminations of silacyclopentene oxides followed by stereospecific transformations. The reaction mechanism of the β-elimination was elucidated by DFT calculations. An in vitro biological assay with an oxy-functionalized silacyclopentane showed substantial binding to a serotonin receptor protein.
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Affiliation(s)
- Kazunobu Igawa
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan.
| | - Daisuke Yoshihiro
- Department of Molecular and Material Sciences, Kyushu University, Japan
| | - Yusuke Abe
- Department of Molecular and Material Sciences, Kyushu University, Japan
| | - Katsuhiko Tomooka
- Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan.
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3
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Igawa K, Yoshihiro D, Abe Y, Tomooka K. Enantioselective Synthesis of Silacyclopentanes. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201511728] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kazunobu Igawa
- Institute for Materials Chemistry and Engineering; Kyushu University; Kasuga Fukuoka 816-8580 Japan
| | - Daisuke Yoshihiro
- Department of Molecular and Material Sciences; Kyushu University; Japan
| | - Yusuke Abe
- Department of Molecular and Material Sciences; Kyushu University; Japan
| | - Katsuhiko Tomooka
- Institute for Materials Chemistry and Engineering; Kyushu University; Kasuga Fukuoka 816-8580 Japan
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Wang ZC, Bierbaum VM. Computational studies of the gas phase reactions of ethers with anions: kinetic barriers, isotope effects, consecutive eliminations and site selectivity. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:141-147. [PMID: 26307694 DOI: 10.1255/ejms.1351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Bimolecular elimination reactions (E2) are fundamentally important processes in organic chemistry. Our current work focuses on a computational investigation of several interesting and unexpected experimental results previously obtained in our laboratory. In particular, we have examined the detailed mechanisms for generating CH(2)CHO(‒) from the reaction of HO(‒) + CH(3)CH(2)OCH(2)CH(2)OCH(3), the unusually large isotope effect (k(D)/k(H) = 5.5) for the reaction of NH(2)(‒) + CH(3)CH(2)OCH(2)CH(3), and the possible kinetic barriers in the reaction of H(‒) + CH(3)CH(2)OCH(2)CH(3). Moreover, we have explored the high site selectivity in the reaction of NH(2)(‒) + CH(3)CH(2)OC(CH(3))(3). In the HO(‒) + CH(3)CH(2)OCH(2)CH(2)OCH(3) reaction, three ion‒neutral encounter complexes were located and fully optimized. The corresponding transition states were confirmed during the first E2 hydrogen-transfer process and they all possess E1(cb)-like antiperiplanar conformations. The formation of loosely bonded CH(3)O(‒) and H(2)O moieties was found to be essential for the second E2-type hydrogen transfer, and an intriguing E1(cb)-like gauche transition state (CH(3)OH-Cα-Cβ- OCHCH(2) dihedral = 40.9°) is located, which results in the formation of ionic CH(2)CHO(‒) and neutral CH(3)OH, H(2)O and C(2)H(4) products. The lowest kinetic barrier for the reaction of NH(2)(‒) + CH(3)CH(2)OCH(2)CH(3) is 5.3 kcal mol(‒1) (1 kcal mol(‒1) = 4.2 kJ mol(‒1)), which is 1.5 kcal mol(‒1) higher in energy than the lowest barrier for the reaction HO(‒) + CH(3)CH(2)OCH(2)CH(3). The higher kinetic barrier of the NH(2)(‒) + CH(3)CH(2)OCH(2)CH(3) reaction is consistent with the observation of a larger isotope effect. The lowest kinetic barrier for the reaction of H(‒) + CH(3)CH(2)OCH(2)CH(3) is +5.4 kcal mol(‒1), indicating that, although H(‒) is a strong base, this reaction cannot occur at room temperature, which agrees well with the experimental results. The high selectivity in the formation of CH(3)CH(2)O(‒) from the reaction of NH(2)(‒) + CH(3)CH(2)OC(CH(3))(3) is explained by an electrostatic potential analysis of the ether molecule. Thus, this computational study provides important insight into the detailed mechanisms of elimination reactions.
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Affiliation(s)
- Zhe-Chen Wang
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
| | - Veronica M Bierbaum
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA.
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Ramu Ramachandran B, Waithe S, Pratt LM. Correction to Rearrangement Reactions of Lithiated Oxiranes. J Org Chem 2013. [DOI: 10.1021/jo4026397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ramachandran BR, Waithe S, Pratt LM. Rearrangement reactions of lithiated oxiranes. J Org Chem 2013; 78:10776-83. [PMID: 24079374 DOI: 10.1021/jo401763v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first computational study of the rearrangement reactions of oxiranes initiated by lithium dialkylamides is presented. Aside from the well-known carbenoid insertion pathways, both β-elimination and α-lithiation have been suggested as the exclusive mechanism by which oxiranes react in the presence of organolithium bases. The products of the former are allyl alcohols (and, in some cases, dienes) and are ketones in the case of the latter. The computational studies reported in this work indicate that both mechanisms could be simultaneously operational. In particular, our work shows that the allyl alcohols from β-elimination are unlikely to undergo 1,3-hydrogen transfer to the vinyl alcohols and thus to the ketones, suggesting that ketones are formed through the opening of the oxirane ring after α-substitution. Elimination of LiOH from the lithiated allyl alcohol is found to result in the diene product. Low activation barriers for β-elimination are offered as the explanation for the few special cases where the allyl alcohol is the dominant or exclusive product. These findings are consistent with the product distributions observed in several experiments.
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Affiliation(s)
- B Ramu Ramachandran
- College of Engineering & Science, Louisiana Tech University , Ruston, Louisiana 71272, United States
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Morgan KM, Brown G, Pichon MA, Green GY. β-Elimination of an Aziridine to an Allylic Amine: A Mechanistic Study. J PHYS ORG CHEM 2013; 24:1144-1150. [PMID: 23293425 DOI: 10.1002/poc.1838] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The base-induced rearrangement of aziridines has been examined using a combination of calculations and experiment. The calculations show that the substituent on nitrogen is a critical feature that greatly affects the favorability of both α-deprotonation, and β-elimination to form an allylic amine. Experiments were carried out to determine whether E2-like rearrangement to the allylic amine with lithium diisopropyl amide (LDA) is possible. N-Tosyl aziridines were found to deprotonate on the tosyl group, preventing further reaction. A variety of N-benzenesulfonyl aziridines having both α- and β-protons decomposed when treated with LDA in either tetrahydrofuran or hexamethylphosphoramide. However, when α-protons were not present, allylic amine was formed, presumably via β-elimination.
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Affiliation(s)
- Kathleen M Morgan
- Department of Chemistry, Xavier University of Louisiana, 1 Drexel Drive, New Orleans LA 70125, USA
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Ma Y, Collum DB. Lithium diisopropylamide-mediated reactions of imines, unsaturated esters, epoxides, and aryl carbamates: influence of hexamethylphosphoramide and ethereal cosolvents on reaction mechanisms. J Am Chem Soc 2007; 129:14818-25. [PMID: 17985891 DOI: 10.1021/ja074554e] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Several reactions mediated by lithium diisopropylamide (LDA) with added hexamethylphosphoramide (HMPA) are described. The N-isopropylimine of cyclohexanone lithiates via an ensemble of monomer-based pathways. Conjugate addition of LDA/HMPA to an unsaturated ester proceeds via di- and tetra-HMPA-solvated dimers. Deprotonation of norbornene epoxide by LDA/HMPA proceeds via an intermediate metalated epoxide as a mixed dimer with LDA. Ortholithiation of an aryl carbamate proceeds via a mono-HMPA-solvated monomer-based pathway. Dependencies on THF and other ethereal cosolvents suggest that secondary-shell solvation effects are important in some instances. The origins of the inordinate mechanistic complexity are discussed.
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Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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Collum DB, McNeil AJ, Ramirez A. Lithium diisopropylamide: solution kinetics and implications for organic synthesis. Angew Chem Int Ed Engl 2007; 46:3002-17. [PMID: 17387670 DOI: 10.1002/anie.200603038] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lithium diisopropylamide (LDA) is a prominent reagent used in organic synthesis. In this Review, rate studies of LDA-mediated reactions are placed in the broader context of organic synthesis in three distinct segments. The first section provides a tutorial on solution kinetics, emphasizing the characteristic rate behavior caused by dominant solvation and aggregation effects. The second section summarizes substrate- and solvent-dependent mechanisms that reveal basic principles of solvation and aggregation. The final section suggests how an understanding of mechanism might be combined with empirical methods to optimize yields, rates, and selectivities of organolithium reactions and applied to organic synthesis.
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Affiliation(s)
- David B Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
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Collum D, McNeil A, Ramirez A. Lithiumdiisopropylamid: Reaktionskinetik in Lösung und Folgerungen für die organische Synthese. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603038] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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13
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Pratt LM, Lê LT, Truong TN. A computational study of mixed aggregates of chloromethyllithium with lithium dialkylamides. J Org Chem 2005; 70:8298-302. [PMID: 16209570 DOI: 10.1021/jo051031l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DFT calculations were performed to examine the possible formation of mixed aggregates between chloromethyllithium carbenoids and lithium dimethylamide (LiDMA). In the gas phase mixed aggregates were readily formed and consisted of mixed dimers, mixed trimers, and mixed tetramers. THF solvation disfavored the formation of mixed tetramers and resulted in less exergonic free energies of mixed dimer and mixed trimer formation.
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Affiliation(s)
- Lawrence M Pratt
- Department of Chemistry, Fisk University, Nashville, Tennessee 37209, USA.
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Abstract
[reaction: see text] Computational methods were used to determine the structure, bonding, and aggregation states of oxiranyllithium in the gas phase and in THF solution, at 200 and 298 K. THF solvation was modeled by microsolvation with explicit THF ligands, forming a supermolecule that includes the oxiranyllithium aggregate and its first solvation shell. Because oxiranyllithium has a chiral center, two diastereomeric dimers were formed, the RR and the RS, along with their enantiomers. Similarly, three diastereomers of the tetramer were formed, the RRRR, RRRS, and RRSS and their enantiomers. Oxiranyllithium was found to exist predominantly as the tetramer in the gas phase, while the dimer was the dominant species in THF solution. The relative concentrations of the different stereoisomers were calculated from equilibrium constants.
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Affiliation(s)
- Lawrence M Pratt
- Department of Chemistry, Fisk University, 1000 17th Avenue North, Nashville, Tennessee 37208, USA.
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O'Brien P, Rosser CM, Caine D. On the α-lithiation-rearrangement of N-toluensulfonyl aziridines: mechanistic and synthetic aspects. Tetrahedron 2003. [DOI: 10.1016/j.tet.2003.09.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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16
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Wiedemann SH, Ramírez A, Collum DB. Lithium 2,2,6,6-Tetramethylpiperidide-Mediated α- and β-Lithiations of Epoxides: Solvent-Dependent Mechanisms. J Am Chem Soc 2003; 125:15893-901. [PMID: 14677981 DOI: 10.1021/ja0304087] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lithium 2,2,6,6-tetramethylpiperidide (LiTMP)-mediated alpha- and beta-lithiations of epoxides are described. LiTMP displays a markedly higher reactivity than does lithium diisopropylamide, consistent with literature reports. Detailed rate studies of LiTMP/THF and LiTMP/Me(2)NEt mixtures reveal similar rates but significant mechanistic differences. LiTMP-mediated alpha-lithiation of cis-cyclooctene oxide with subsequent oxacarbenoid formation and transannular C-H insertion proceeds via monosolvated dimers in both THF and Me(2)NEt. LiTMP-mediated beta-lithiation of 2,3-dimethyl-2-butene oxide affords the corresponding allylic alcohol via a monosolvated monomer in THF and a monosolvated dimer in Me(2)NEt. We discuss how the solvent-dependent aggregation of LiTMP markedly influences the rate profile. The reaction transition structures are examined with density functional computations.
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Affiliation(s)
- Sean H Wiedemann
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
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17
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Enantioselective Synthesis by Lithiation Adjacent to Oxygen and Subsequent Rearrangement. TOP ORGANOMETAL CHEM 2003. [DOI: 10.1007/3-540-36117-0_7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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18
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de Sousa SE, O'Brien P, Pilgram CD. Optimisation of enantioselectivity for the chiral base-mediated rearrangement of bis-protected meso-4,5-dihydroxycyclohexene oxides: asymmetric synthesis of 4-deoxyconduritols and conduritol F. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00370-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Morgan KM, O'Connor MJ, Humphrey JL, Buschman KE. An experimental and computational study of 1,2-hydrogen migrations in 2-hydroxycyclopentylidene and its conjugate base. J Org Chem 2001; 66:1600-6. [PMID: 11262102 DOI: 10.1021/jo001038x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thermal decomposition of alpha-hydroxydiazirine 2 gives primarily cyclopentanone and some allylic alcohol, in similar amounts as the known cyclohexyl analogue 1. Calculations (B3LYP/6-31+G) also show cyclopentanone to be the major product of this carbene rearrangement. Diazirine 2 and the lithium salt of the corresponding conjugate base 3 were decomposed by photolysis. The proportion of ketone formed increases with deprotonation, a trend also found computationally. In comparison, the base-induced isomerization of cyclopentene oxide, which proceeds via alpha-elimination to a carbenoid intermediate similar to that obtained from 3, yields primarily allylic alcohol rather than ketone; neither ring size nor charge thus accounts for the unusual product distribution observed. Interestingly, the calculations reveal that in the gas phase with no counterion, the singlet, oxyanionic carbene, and the alpha-deprotonated epoxide are the same, rather than discrete structures. This intramolecular complexation stablilizes the oxyanionic carbene by 20-25 kcal/mol.
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Affiliation(s)
- K M Morgan
- Department of Chemistry, The College of William & Mary, P.O. Box 8795, Williamsburg, VA 23187-8795, USA.
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Structural and solvent effects on the mechanism of base-induced rearrangement of epoxides to allylic alcohols. J Org Chem 2000; 65:1461-6. [PMID: 10814110 DOI: 10.1021/jo991619q] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combined experimental and computational study is presented which explores the influence of structure and solvent on the base-catalyzed isomerization of cyclopentene- and cyclohexene oxides. Cyclohexene oxide is known to rearrange via a syn beta-elimination in nonpolar solvents. Cyclopentene oxide instead undergoes alpha-elimination to a carbenoid intermediate in nonpolar solvents due to the unusual acidity of the alpha-proton, not because of an unfavorable conformation. In HMPA, cyclopentene oxide undergoes beta-elimination. To explore the origins of this mechanistic change, deuterium-labeled cis-4-tert-butylcyclohexene oxide was rearranged in HMPA and was found to react via anti beta-elimination, as presumably do cyclopentene oxide and other epoxides.
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Ramírez A, Collum DB. Hemi-Labile Ligands in Organolithium Chemistry: Rate Studies of the LDA-Mediated α- and β-Metalations of Epoxides. J Am Chem Soc 1999. [DOI: 10.1021/ja992166+] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Nilsson Lill SO, Arvidsson PI, Ahlberg P. Computational study of solvation and stereoselectivity in deprotonation of cyclohexene oxide by a chiral lithium amide. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s0957-4166(98)00501-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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23
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O’Brien P. Recent advances in asymmetric synthesis using chiral lithium amide bases. ACTA ACUST UNITED AC 1998. [DOI: 10.1039/a705961e] [Citation(s) in RCA: 216] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hudrlik PF, Tafesse L, Hudrlik AM. Regiochemical Effect of an α-Trimethylsilyl Group on Epoxide Reactions with Non-nucleophilic Bases. J Am Chem Soc 1997. [DOI: 10.1021/ja972256j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul F. Hudrlik
- Department of Chemistry, Howard University Washington, D.C. 20059
| | - Laykea Tafesse
- Department of Chemistry, Howard University Washington, D.C. 20059
| | - Anne M. Hudrlik
- Department of Chemistry, Howard University Washington, D.C. 20059
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Hodgson DM, Gibbs AR. On the mechanism of lithium amide-induced rearrangements of 4-substituted cyclopentene oxides to cyclopentenols. Tetrahedron Lett 1997. [DOI: 10.1016/s0040-4039(97)10358-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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26
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Saravanan P, DattaGupta A, Bhuniya D, Singh VK. Studies in the rearrangement of epoxides with lithium dialkylamide-lithium tert-butoxide. Tetrahedron 1997. [DOI: 10.1016/s0040-4020(96)01102-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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27
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Affiliation(s)
- Tsuyoshi Satoh
- Faculty of Pharmaceutical Sciences, Science University of Tokyo, Ichigaya-funagawara-machi, Shinjuku-ku, Tokyo, 162, and Department of Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka, Shinjuku-ku, Tokyo 162, Japan
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