ASYMMETRIC RADICAL ADDITIONS USING CHIRAL 1,3-DIOXOLANE-4-ONES

Moderate facial selectivities are observed in additions of alkyl radicals to the chiral (c,d) olefin (2S)-2-tert-butyl-5-ethoxycarbonylmethylene-1,3-dioxolane-4-one 1. The following hydrogen abstraction from tributylstannane proceeds with excellent asymmetric stereocontrol, leading to two of four possible diastereoisomers with high diastereomeric excesses. Additions of chiral radicals obtained from (2R,5R)-5-alkyl-5-bromo-1,3-dioxolane-4-ones to ethyl acrylate show high asymmetric 1,3-induction.