Chiral α,ω-Dioxy-Carbanions from 1,3-Propanediol and 1,4-Butanediol by Sparteine-Assisted Deprotonation. Enantioselective Synthesis of 1,3- and 1,4-Diols, (R)-Pantolactone, and a Cyclopropane

Article abstract of DOI:10.1016/S0040-4039(00)79083-6

Prostereogenic mono- and dicarbamates of 1,3-propanediol and 1,4-butanediol are deprotonated by the sec-butyllithium/(-)-sparteine system with high enantiotopic differentiation.The electrophilic substitution of the intermediate chiral carbanions furnishes the title compounds with >95percent ee. Key words: Chiral 1-oxy-carbanions; enantioselective deprotonation; (-)-sparteine.