α-methylene-β,γ-diphenyl-γ-butyrolactone was synthesized by the bromoprop-2-yn-1-yloxylation of cis-stilbene. Cobaloxime catalyzed radical cyclization of the resulting1-bromo-1, 2-diphenylethylprop-2-yn-1-yl ether, gave 2,3- diphenyl-4-methylene tetrahydrofuran and oxidation of the latter with chromium trioxide in the presence of pyridine, afforded the target product in 62.5% yield. Synthesis of this α-methylene-β,γ-diphenyl-γ-butyrolactone led to efficient anti microbial activity. It was found that it is effective against Gram-positive bacteria, Gram-negative bacteria and yeast. Its extensive inhibition effect is particularly against yeast.