The Experts below are selected from a list of 24981 Experts worldwide ranked by ideXlab platform
Seiji Iwasa - One of the best experts on this subject based on the ideXlab platform.
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regio and enantioselective intramolecular amide carbene insertion into primary c h bonds using ru ii pheox catalyst
Journal of Organic Chemistry, 2019Co-Authors: Yoko Nakagawa, Soda Chanthamath, Yumeng Liang, Kazutaka Shibatomi, Seiji IwasaAbstract:We have established a method for the highly regio- and enantioselective functionalization of Tert-Butyl Groups via intramolecular amide carbene insertion into C–H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C–H bond proceeds rapidly and selectively compared to that with secondary C–H, benzylic secondary C–H, tert-C–H, or sp2C–H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated Tert-Butyl Group with enantiocontrol at the carbenoid carbon.
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Regio- and Enantioselective Intramolecular Amide Carbene Insertion into Primary C–H Bonds Using Ru(II)-Pheox Catalyst
2019Co-Authors: Yoko Nakagawa, Soda Chanthamath, Yumeng Liang, Kazutaka Shibatomi, Seiji IwasaAbstract:We have established a method for the highly regio- and enantioselective functionalization of Tert-Butyl Groups via intramolecular amide carbene insertion into C–H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C–H bond proceeds rapidly and selectively compared to that with secondary C–H, benzylic secondary C–H, tert-C–H, or sp2C–H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated Tert-Butyl Group with enantiocontrol at the carbenoid carbon
James E. Thomson - One of the best experts on this subject based on the ideXlab platform.
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Solid state conformations of α,β-unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxylamine
Tetrahedron-asymmetry, 2017Co-Authors: Stephen G. Davies, Paul M. Roberts, James E. Thomson, James A. Lee, Jingda YinAbstract:Abstract α,β-Unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxylamine consistently adopt a defined conformation and undergo highly diastereoselective conjugate addition reactions with lithium amide reagents. The configuration of the N-1-(1′-naphthyl)ethyl Group dictates the position of the O-Tert-Butyl Group and also the configuration adopted by the pyramidal nitrogen atom via a ‘chiral relay’ effect. Conjugate addition of lithium amide reagents to these substrates proceeds on the face opposite to both the O-Tert-Butyl Group and nitrogen lone-pair with high levels of diastereoselectivity.
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On the origins of diastereoselectivity in the alkylation of enolates derived from N-1-(1'-naphthyl)ethyl-O-Tert-Butylhydroxamates: chiral Weinreb amide equivalents.
Journal of Organic Chemistry, 2010Co-Authors: Stephen G. Davies, Christopher J. Goodwin, David Hepworth, Paul M. Roberts, James E. ThomsonAbstract:The stereochemical outcome observed upon alkylation of enolates derived from N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxamates (chiral Weinreb amide equivalents) may be rationalized by a chiral relay mechanism. Deprotonation with KHMDS leads to a nonchelated (Z)-enolate in which the oxygen atoms adopt an anti-periplanar conformation. The configuration of the N-1-(1′-naphthyl)ethyl Group dictates the conformation of the O-Tert-Butyl Group and the configuration adopted by the adjacent pyramidal nitrogen atom. Highly diastereoselective enolate alkylation then proceeds anti to both the bulky Tert-Butyl Group (sterically driven) and the N-lone pair (stereoelectronically driven).
Stephen G. Davies - One of the best experts on this subject based on the ideXlab platform.
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Solid state conformations of α,β-unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxylamine
Tetrahedron-asymmetry, 2017Co-Authors: Stephen G. Davies, Paul M. Roberts, James E. Thomson, James A. Lee, Jingda YinAbstract:Abstract α,β-Unsaturated hydroxamates derived from the ‘chiral Weinreb amide’ auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxylamine consistently adopt a defined conformation and undergo highly diastereoselective conjugate addition reactions with lithium amide reagents. The configuration of the N-1-(1′-naphthyl)ethyl Group dictates the position of the O-Tert-Butyl Group and also the configuration adopted by the pyramidal nitrogen atom via a ‘chiral relay’ effect. Conjugate addition of lithium amide reagents to these substrates proceeds on the face opposite to both the O-Tert-Butyl Group and nitrogen lone-pair with high levels of diastereoselectivity.
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On the origins of diastereoselectivity in the alkylation of enolates derived from N-1-(1'-naphthyl)ethyl-O-Tert-Butylhydroxamates: chiral Weinreb amide equivalents.
Journal of Organic Chemistry, 2010Co-Authors: Stephen G. Davies, Christopher J. Goodwin, David Hepworth, Paul M. Roberts, James E. ThomsonAbstract:The stereochemical outcome observed upon alkylation of enolates derived from N-1-(1′-naphthyl)ethyl-O-Tert-Butylhydroxamates (chiral Weinreb amide equivalents) may be rationalized by a chiral relay mechanism. Deprotonation with KHMDS leads to a nonchelated (Z)-enolate in which the oxygen atoms adopt an anti-periplanar conformation. The configuration of the N-1-(1′-naphthyl)ethyl Group dictates the conformation of the O-Tert-Butyl Group and the configuration adopted by the adjacent pyramidal nitrogen atom. Highly diastereoselective enolate alkylation then proceeds anti to both the bulky Tert-Butyl Group (sterically driven) and the N-lone pair (stereoelectronically driven).
Yoko Nakagawa - One of the best experts on this subject based on the ideXlab platform.
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regio and enantioselective intramolecular amide carbene insertion into primary c h bonds using ru ii pheox catalyst
Journal of Organic Chemistry, 2019Co-Authors: Yoko Nakagawa, Soda Chanthamath, Yumeng Liang, Kazutaka Shibatomi, Seiji IwasaAbstract:We have established a method for the highly regio- and enantioselective functionalization of Tert-Butyl Groups via intramolecular amide carbene insertion into C–H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C–H bond proceeds rapidly and selectively compared to that with secondary C–H, benzylic secondary C–H, tert-C–H, or sp2C–H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated Tert-Butyl Group with enantiocontrol at the carbenoid carbon.
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Regio- and Enantioselective Intramolecular Amide Carbene Insertion into Primary C–H Bonds Using Ru(II)-Pheox Catalyst
2019Co-Authors: Yoko Nakagawa, Soda Chanthamath, Yumeng Liang, Kazutaka Shibatomi, Seiji IwasaAbstract:We have established a method for the highly regio- and enantioselective functionalization of Tert-Butyl Groups via intramolecular amide carbene insertion into C–H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C–H bond proceeds rapidly and selectively compared to that with secondary C–H, benzylic secondary C–H, tert-C–H, or sp2C–H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated Tert-Butyl Group with enantiocontrol at the carbenoid carbon
Masahiko Hayashi - One of the best experts on this subject based on the ideXlab platform.
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simple preparation of β amino alcohols possessing a tert butyl Group at the α carbon
ChemInform, 2012Co-Authors: James T. Zacharia, Takanori Tanaka, Yumiko Uesaka, Masahiko HayashiAbstract:Among the title compounds, derivatives (Ic) and (Id) which bear the Tert-Butyl Group at the α-carbon, are shown to be efficient catalysts for the asymmetric addition of diethylzinc to benzaldehyde.
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Simple Preparation of β-Amino Alcohols Possessing a Tert-Butyl Group at the α-Carbon
Synthesis, 2012Co-Authors: James T. Zacharia, Takanori Tanaka, Yumiko Uesaka, Masahiko HayashiAbstract:Simple preparation of β-amino alcohols possessing a tert -butyl Group at the α-carbon was achieved. These β-amino alcohols proved to work effectively as catalysts in the enantioselective alkylation of aldehydes.
