Abstract: Enantiomerically pure benzyl cis-a,@-epoxy carboxylates were prepared by a modified Darzens procedure employing an aldol condensation on chiral a-haloimides with various aldehydes. This aldol reaction was mediated by metal and non-metal cations of different oxygen chelating characteristics (Li, Zn, Sn", SnIV, and B) in THF or ether generally at-78 OC. Stereoselectivity was found to be dependent on experimental conditions and ...
