Synthesis of Enantioenriched α-(Hydroxyalkyl)-tri-n-butylstannanes

摘要

A catalytically asymmetric synthesis of α-(hydroxyalkyl)-tri-n-butylstannanes >1 in good-excellent yields and enantioselectivities (up to 98% e.e.) via addition of ethyl(tri-n-butylstannyl)zinc to aldehydes was achieved. In practice, >1 was isolated after protection as its more stable ester or thiocarbamate (PG). The reagent was prepared from equimolar amounts of tri-n-butylstannyl hydride and Et2Zn in DME so as to avoid contamination by lithium and magnesium ions which suppress enantioselectivity.