Reaction of 2-substituted 1-buten-3-ynes (CH2=CR-C=CH) with catecholborane in the presence of a palladium catalyst bearing a monodentate phosphine ligand such as PPh3 or PPh2(C6F5) proceeded in a 1,4-fashion to give (3-substituted 1,2-butadienyl)-1,3,2-benzodioxaboroles (CH3(R)C=C=CH(BO2C6H4)). Reaction of the allenylboranes with benzaldehyde gave the corresponding homopropargyl alcohols.