α-Chloro-β,γ-ethylenic esters: enantiocontrolled synthesis and substitutions.

Chiral nonracemic γ-seleno-α,β-ethylenic esters, when treated with sulfuryl chloride and ethyl vinyl ether in hexanes, produced α-chloro-β,γ-ethylenic esters in 65-75% yields, with ee values of 95-97%, and with 1,3-syn transfer of chirality. Reaction of these allylic chloride electrophiles with methylcuprate and with sodium azide nucleophiles afforded exclusively γ-substituted-α,β-ethylenic esters with faithful anti-transfer of chirality on multigram scale.