Addition of the dianion of (+)-(R)-3-[(4-methylphenyl)sulphinyl]propionic acid (1) to aldehydes affords two main diastereoisomeric β-sulphinyl-γ-lactones, pyrolysis of which gives the two enantiomers of 5-substituted furan-2(5H)-ones in optically pure form.
The first highly asymmetric Pummerer-type cyclization of chiral, non-racemic β-amidosulfoxides leading to enantiomerically enriched β-lactams (80–85 % ee) is described. S-and R-sulfoxides ( and ) were treated with O-methyl-O-tert-butyldimethylsilyl ketene acetal (1) in the presence of a catalytic amount of ZnCl2 in CH2Cl2 to predominantly give the corresponding 4R- and 4S-β-lactams ( and ) in more
1,4 Asymmetric induction in the carbonyl reduction of a γ-ketosulfoxide
作者:Guy Solladie、Françoise Colobert、Frédéric Somny
DOI:10.1016/s0040-4039(98)02572-6
日期:1999.2
a chiral sulfoxide induced high stereoselectivity in the DIBAL-H reduction of a methyl ketone located in the γ position as a result of a 1,4-asymmetric induction. Addition of a lanthanide triflate or cerium chloride completely reversed the stereoselectivity.