Stereoselective Transition Metal-Catalyzed [(2+2)+1] and [(2+2)+2] Carbocyclization Reactions using 1,6-Enynes with 1,1-Disubstituted Olefins: Construction of Quaternary Centers

Abstract

Transition metal-catalyzed carbocyclization reactions offer a powerful method for the stereoselective assembly of complex, highly substituted (poly)cyclic scaffolds. Although 1,6-enynes are common substrates for these transformations, using polysubstituted alkene derivatives to construct functionalized cyclic products remains challenging due to significantly lower reactivity. This Perspective highlights key developments in stereoselective metal-catalyzed [(2+2)+1] and [(2+2)+2] carbocyclizations of 1,6-enynes containing 1,1-disubstituted alkenes, which produce cycloadducts with quaternary stereogenic centers. The insights from these examples provide a blueprint for developing more general carbocyclization strategies with challenging polysubstituted olefins.