Re(I)-catalyzed hydropropargylation of enamides: a useful method for the preparation of 4-pentynylamine derivatives.

Hydropropargylation of enamides was achieved in good yields through the 1,4-addition of enamides to the α,β-unsaturated carbene complex intermediate, followed by intramolecular hydrogen transfer to the iminium carbon. This method is useful for the synthesis of 4-pentynylamine derivatives from enamides and easily available propargyl ether. Moreover, tandem cyclization reaction was achieved to afford a pyrrolidine derivative in a single operation by using a secondary enamide.