Catalytic Asymmetric [4 + 3] Annulation of C, N-Cyclic Azomethine Imines with Copper Allenylidenes.

The first asymmetric decarboxylative [4 + 3] annulation of propargylic carbamates with C, N-cyclic azomethine imines has been developed successfully by a copper- N-heterocyclic carbine system. This strategy led to a series of optically active isoquinoline-fused triazepine derivatives in good yields and with excellent enantio- and diastereoselectivities. Remarkably, Cu-allenylidene intermediates play a crucial role in this transformation.