Asymmetric, Organocatalytic, Three-Step Synthesis of α-Hydroxy-(E)-β,γ-unsaturated Esters

An efficient and enantiocontrolled three-step synthesis of alpha-hydroxy-(E)-beta,gamma-unsaturated esters is reported. Enantioenriched alpha-selenyl aldehydes, prepared in one step by asymmetric, organocatalytic alpha-selenylation of aldehydes, were directly subjected to a Wittig reaction followed by allylic selenide to selenoxide oxidation and final spontaneous [2,3]-sigmatropic rearrangement to yield the target compounds in 43-65% overall yield and in 94-97% ee.