Transition-metal-mediated cascade reactions:: C,C-dicyclopropylmethylamines by way of double C,C-σ-bond insertion into bicyclobutanes

The organometallic multicomponent reaction of alkenyl zirconocene, alkynyl imine, and zinc carbenoid in the presence of dimethylzinc leads to novel C,C-dicyclopropylmethylamines. The formation of intermediate bicyclo[1.1.0]butanes represents the first synthetically useful example of a double C,C-σ-bond insertion, and the increase in structural complexity from starting materials is highlighted by the formation of nine new C,C-bonds in the final product. Copyright © 2003 American Chemical Society.