Nucleophilic substitution on α-mesyloxy-O-alkyloximes—I. Enantiospecific synthesis of 2-(imidazol-1-yl)-1,3-diphenylpropan-1-one O-alkyloximes
摘要:
An enantiospecific synthesis of (S)- and (R)-(E)-5-[1,3-diphenyl-2-(imidazol-l-yl)propylidene] aminooxypentanoic acids 1 using homochiral phenylalanines as starting material is described. Chiral alpha-hydroxyketones 9 were obtained from alpha-hydroxyacids 7 by Weinreb's ketone synthesis. Imidazole introduction by nucleophilic substitution on mesylate 10 led to 2-(imidazol-1-yl)propan-1-one derivative 3, key intermediate in the synthesis of 1. However, the low configurational stability displayed by compound 3 compromised its use in an enantiospecific synthesis. Homochiral compounds 1 were then obtained by a nucleophilic substitution on alpha-mesyloxy-O-alkyloxymes 14 which were in turn obtained from 9. This nucleophilic substitution on alpha-mesyloxy-O-alkyloxymes was not previously reported either on homochiral compounds or on racemic derivatives. (C) 1997 Elsevier Science Ltd.
Rearrangement of <i>N</i>-<i>tert</i>-Butanesulfinyl Enamines for Synthesis of Enantioenriched α-Hydroxy Ketone Derivatives
作者:Chun-Tian Li、Hui Liu、Yun Yao、Chong-Dao Lu
DOI:10.1021/acs.orglett.9b03159
日期:2019.10.18
hexamethyldisilazide (or potassium tert-butoxide) and methyl triflate gives N-methylated N-tert-butanesulfinyl enamine intermediates that undergo stereoselective [2,3]-rearrangement to afford α-sulfenyloxy ketones with excellent enantiopurities. This cascade of enamination-N-methylation-rearrangement was even used to generate acyclic tertiary α-hydroxy ketones bearing two α-substituents showing negligible
Enantioselective Acyloin Rearrangement of Acyclic Aldehydes Catalyzed by Chiral Oxazaborolidinium Ion
作者:Soo Min Cho、Si Yeon Lee、Do Hyun Ryu
DOI:10.1021/acs.orglett.1c00314
日期:2021.2.19
A catalytic enantioselective acyloin rearrangement of acyclic aldehydes to synthesize highly optically active acyloin derivatives is described. In the presence of a chiral oxazaborolidinium ion catalyst, the reaction provided chiral α-hydroxy aryl ketones in high yield (up to 95%) and enantioselectivity (up to 98% ee). In addition, the enantioselective acyloin rearrangement of α,α-dialkyl-α-siloxy
MAIGROT, N.;MAZALEYRAT, J. -P.;WELVART, Z., J. ORG. CHEM., 1985, 50, N 20, 3916-3918
作者:MAIGROT, N.、MAZALEYRAT, J. -P.、WELVART, Z.
DOI:——
日期:——
ENDERS, D.;LOTTER, H.;MAIGROT, N.;MAZALEYRAT, J. -P.;WELVART, Z., NOUV. J. CHIM., 1984, 8, N 12, 747-750
作者:ENDERS, D.、LOTTER, H.、MAIGROT, N.、MAZALEYRAT, J. -P.、WELVART, Z.
DOI:——
日期:——
Pd-Catalyzed Decarboxylative Cycloaddition for the Synthesis of Highly Substituted δ-Lactones and Lactams
作者:Linlin Shi、Yingdong He、Jianxian Gong、Zhen Yang
DOI:10.1021/acs.organomet.0c00646
日期:2021.2.8
An efficient palladium-catalyzed decarboxylative cycloaddition process of vinyl cyclic carbonates and vinyloxazolidinones for the synthesis of highlysubstituted δ-lactone and δ-lactam derivatives was developed. This protocol exhibits several unique characteristics, including broad substrate scope, good functional group tolerance, and operational convenience, which enables a regioselective access to