Asymmetric synthesis of (R)- and (S)-4-(substituted benzyl)dihydrofuran-2(3H)-ones: an application of the ruthenium-binap complex-catalysed asymmetric hydrogenation of alkylidenesuccinic acids
A concise synthesis of (S)- or (R)-4-(substituted benzyl)dihydrofuran-2(3H)-ones (1) with high enantiomeric purity is presented. (S)- or (R)-(Substituted benzyl)succinic acids (6) 97% enantiomeric excess) were first prepared by Ru2Cl4[(R)- or (S)-binap)]2(NEt3) catalysed asymmetrichydrogenation of (substituted benzylidene)succinic acids. The diacids (6) were converted into (R)- or (S)-2-(substituted
Enantioselective Carbometalation of Cinnamyl Derivatives: New Access to Chiral Disubstituted Cyclopropanes— Configurational Stability of Benzylic Organozinc Halides
作者:Stephanie Norsikian、Ilan Marek、Sophie Klein、Jean F. Poisson、Jean F. Normant
Diastereoselective conjugate addition of Grignard reagents to a homochiral fumaramide derived from Oppolzer’s sultam
作者:Gary P. Reid、Kieron W. Brear、David J. Robins
DOI:10.1016/j.tetasy.2003.12.010
日期:2004.3
Conjugate addition of Grignard reagents to N,N'-fumaroylbis[(2R)-bornane-10,2-sultam] 1 occurred with moderate to high levels of diastereoselectivity. Diastereomeric excesses were estimated by analysis of the H-1 NMR spectra of the succinamide mixtures and enantiomeric excesses from F-19 NMR spectra of the bis Mosher esters of the diols produced by reductive cleavage of the succinamides. Saponification of the succinamides gave the corresponding (R)-succinic acids with ees up to 92% showing that addition of the Grignard reagents takes place selectively on the re-face of 1. (C) 2003 Elsevier Ltd. All rights reserved.