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 carbocyclization followed by regioslective addition of organoboronic acids in the presence of Pd(OAc)2 and tri-t-butylphosphine under mild reaction conditions.