Enantioselective Cyclopropanation of (Z)‐3‐Substituted‐2‐(4‐pyridyl)‐acrylonitriles Catalyzed by Cinchona Ammonium Salts.

Cyclopropane esters holding two quaternary centres were prepared in high yields, complete diastereoselection and up to 83% ee. The reaction described herein entailed reacting (Z)-3-substituted-2-(4-pyridyl)-acrylonitrile, a reactive class of Michael acceptor, with 2-bromomalonate esters in the presence of Cinchona derived phase-transfer catalysts. The reaction allowed multi-gram preparation of the desired products.