Unprecedented carbocyclization of 1,6-allenynes on addition of organoboronic acids under Pd-catalysis

In contrast to the ene behavior of allenes in Pauson-Khand reactions and other cyclization reactions, 1,6-allenynes undergo unprecedented carbocyclization followed by regioselective addition of organoboronic acids in the presence of Pd(OAc)(2) and tri-t-butyl phosphine under mild reaction conditions. (c) 2005 Elsevier Ltd. All rights reserved.