CuBr-catalyzed homologation of alk-1-ynes 1 with paraformaldehyde and N, N- diisopropylamine (or N, N-dicyclohexylamine) was accelerated by microwave irradiation at 150° C to afford the corresponding allenes 2 in good to high yields in 1–10min. Bisalkynes 5 and 7 were also converted to the corresponding bisallenes 6 and 8 in 63% and 61% yields, respectively, under the current condition.
