Synthesis of cyclic cis-enediynes from manganese carbyne complexes and a,w-diynes

Cyclic cis-enediynes are readily prepared by a two-step one-pot procedure. The first step is the copper-catalyzed addition of alpha,omega-diynes to manganese carbyne complexes to give intermediate bis(alkynylcarbene) complexes that rearrange to enediyne complexes below room temperature. In the second step, the free enediyne is released from manganese by photolysis, copper-catalyzed air oxidation, or stoichiometric Cu(II) oxidation. These new procedures have been applied to a variety of five-, six-, and seven-membered-ring cyclic enediynes containing a range of ether, ester, and ketone functional groups.