Copper‐Catalyzed Synthesis of Tetrasubstituted Allenes from Quaternary Ammonium Salts and Grignard Reagents

Abstract

Although the synthesis of allenes has made considerable progress, methods for tetrasubstituted allenes are still limited. In this paper,t he CuBr 2 -catalyzed crosscoupling reaction of Grignardr eagents and propargylic ammonium salts in tetrahydrofuran at 60 8Cu nder argon delivered tetrasubstituted allenes in good to excellent yields. The reactioni st hought to proceed by an S N 2' pathway.