2, 2-Dibromo 1, 3-diones reacted with copper powder and olefin to give 2, 3-dihydrofuran derivatives in a highly regioselective fashion. Acetylenes and 1, 3-dienes also reacted with 2, e-dibromo 1, 3-diones and copper to afford furan derivatives and 2-vinyl-2, 3-dihydrofuran derivatives, respectively. In benzene copper was converted into copper (1) bromide during the course of reaction, whereas in Me2S0 copper was converted into copper (I1) bromide. ...