Asymmetric Trapping of an Alcoholic Oxonium Ylide with Aldehydes

Significance

Previously, the authors have reported a non-enantioselective multicomponent reaction sequence involving trapping of an alcoholic oxonium ylide with aldehydes using Lewis acids. In the present paper the corresponding enantio­selective version of this reaction is described through use of a zirconium-binol system developed by Kobayashi. Reactions of aryl diazoacetates, benzyl alcohol, and aromatic aldehydes provide very useful dihydroxylated ester compounds containing an all-carbon stereogenic center in high diastereomeric ratios and enantioselectivities.