A copper-free palladium catalyzed cross coupling reaction of vinyl tosylates with terminal acetylenes

Abstract A copper-free palladium-catalyzed cross coupling of vinyl tosylate ( 2 ) and terminal acetylenes was investigated, affording a convenient and efficient method for construction of an sp – sp 2 carbon carbon bond. The tosylate ( 2 ) derived from 1,3-cyclohexanedione was reacted with terminal acetylene under the copper-free conditions at ambient temperature, in the presence of palladium acetate and triphenylphosphine, to provide the conjugated en-yn-one products in excellent overall yields while leaving other functional groups intact. This reaction protocol was extended to coumarin tosylate ( 12 ).