Enantioselective Additive Pummerer-Type Reaction in Chiral, Non-racemic Vinyl Sulfoxides Induced by O-Silylated Ketene Acetal.

Treatment of chiral, non-racemic vinyl sulfoxides with O-silylated ketene acetal in the presence of a catalytic amount of zinc chloride in tetrahydrofuran resulted in an enantioselective Pummerer-type reaction, affording a considerable yield of the corresponding enantiomerically enriched methyl 4-siloxy-4-sulfenylbutyrate in 78-82% ee.