Copper-promoted [2+2+2] annulation of 1,n-enynes through decomposition of azobis(alkyl nitrile)s.

A novel copper-promoted [2+2+2] annulation of 1,n-enynes with azobis(alkyl nitrile)s and H ₂ O for the synthesis of diverse 7,8-dihydrophenanthridine-6,9(5H,6aH)-diones and fluorene is described. The reaction proceeds via the decomposition of azobis(alkyl nitrile)s into the cyanoalkyl radicals as the two-carbon units and offers a new efficient tool for the one-step formation of four new chemical bonds.