ETUDE DE LA REACTION CHLOROCARBENE-ACETALS DE CETENES. II. STEREOSELECTIVITE DE LA REACTION.

Article abstract of DOI:10.1016/S0040-4020(01)96367-7

We have studied the stereoselectivity of the addition reaction of chloro and chloromethyl carbenoids with ketene alkylsilyl acetals.The best stereoselectivity was generally observed with the dimethyl tertiobutylsilyloxy group.With the chlorocarbenoid, using an E ketene acetal we obtained in majority (ca. 80percent) an E α,β-ethylenic ester and using a Z ketene acetal we obtained in majority (ca. 70percent) a Z α,β-ethylenic ester.In the case of the chloromethyl carbenoid the two ketene acetal isomers led to the same α-substituted α,β-ethylenic ester (ca. 88percent of selectivity).With the chlorophenylcarbenoid, formation of ca. 90percent of E α phenyl α,β-ethylenic ester is observed.