Preparation of spiro[imidazolidine-4,3′-indolin]-2′-imines via copper(i)-catalyzed formal [2 + 2 + 1] cycloaddition of 3-diazoindolin-2-imines and triazines

Abstract

We report a facile and efficient synthesis of spiro[imidazolidine-4,3′-indolin]-2′-imines via a copper(I)-catalyzed cascade reaction of 3-diazoindolin-2-imines with 1,3,5-triazines. The reaction proceeds under very mild conditions and tolerates a variety of functional groups. The cascade process involves the formation of a copper–carbene intermediate and a formal [2 + 2 + 1] cycloaddition.