Mechanism and reactivity of catalytic propargylic substitution reactions via metal-allenylidene intermediates: a theoretical perspective

Development of transition metal-catalyzed propargylic substitution reactions is still in progress as a novel synthetic tool, while a variety of allylic substitution reactions have been well established and widely used in organic synthesis. In this review, we summarize the mechanism and reactivity of transition metal-catalyzed propargylic substitution reactions from a theoretical point of view. We classify the reaction mechanisms for transition metal-catalyzed propargylic substitution reactions which have been reported to date, and then discuss, in particular, the reactions via metal-allenylidene intermediates.