Synthesis of Activated Cyclopropanes by an MIRC Strategy: An Enantioselective Organocatalytic Approach to Spirocyclopropanes

Abstract

Abstract An efficient cyclopropanation, by a Michael‐initiated ring‐closing (MIRC) reaction of 2‐arylidene‐1,3‐indandiones and 2‐arylidene malononitriles, has been developed by using different α‐monohalogenated methylene active compounds with triethylamine. The first enantioselective cyclopropanation to spirocyclopropanes derived by the reaction of 2‐arylidene‐1,3‐indandiones and dimethyl bromomalonate with a commercially available α,α‐ L ‐diarylprolinol as the organocatalyst and K 2 CO 3 as the additive has been accomplished. The spirocyclopropanes were isolated in high yield and up to 85 % ee . Notably, the asymmetric one‐pot sequential approach to spirocyclopropanes proved to be a feasible process.