Catalytic Asymmetric Synthesis of Zinc Metallacycles.

Transition-metal-catalyzed reductive coupling reactions of alkynes and imines are attractive methods for the synthesis of chiral allylic amines. Mechanistically, these reactions involve oxidative cyclization of the alkyne and the imine to generate a metallacyclic intermediate, which then reacts with H or a H surrogate to form the product. As an alternative to this hydrogenolysis pathway, here we show that transmetalation to zinc can occur, forming a zinc metallacycle product.