Asymmetric Synthesis of Bispiro[γ‐butyrolactone‐pyrrolidin‐4,4′‐pyrazolone] Scaffolds Containing Two Quaternary Spirocenters via an Organocatalytic 1,3‐Dipolar Cycloaddition

Abstract

Enantiomerically enriched bispiro[γ‐butyrolactone‐pyrrolidin‐4,4′‐pyrazolone] skeletons were synthesized firstly through a simple organocatalytic 1,3‐dipolar cycloaddition reaction between α‐imino γ‐lactones and alkylidene pyrazolones in high yields and excellent stereoselectivities. This efficient organocatalytic strategy provides facile access to a variety of highly functionalized drug‐like compounds with two quaternary spirocenters and should allow for structure diversification of this intriguing class of compounds.