Titanium(salalen) complex 1 was an effective catalyst for asymmetric epoxidation of enol esters. Although (E)-enol esters were reluctant to proceed, (Z)-enol esters underwent asymmetric epoxidation to give the epoxides in high yields with high enantioselectivity ranging from 86 to >99% ee in the presence of aqueous hydrogenperoxide as the stoichiometric oxidant. Complete enantioselectivity was observed
Enantioselective Synthesis and Stereoselective Rearrangements of Enol Ester Epoxides
作者:Yuanming Zhu、Lianhe Shu、Yong Tu、Yian Shi
DOI:10.1021/jo001593z
日期:2001.3.1
Enolesters can be epoxidized with high enantioselectivities using the fructose-derived chiral ketone 1 as catalyst and Oxone as oxidant. A detailed study of enantiomerically enriched enolesterepoxides has revealed that the acid-catalyzedrearrangement can proceed through two distinct pathways, one with retention of configuration and the other with inversion. The competition between the two pathways