The reaction of substituted 2-alkynyl carbonates with terminal acetylenes in the presence of palladium-phosphine complex and copper(I) iodide proceeds to give 1,2-dien-4-ynes.
Palladium-catalyzed reaction of 2-alkynyl carbonates (propargylic carbonates) with olefins proceeds smoothly in the presence of triethylamine and potassium bromide to give vinyl allenes (1,2,4-trienes) in good yields.