First Synthesis of cis-Enediynes from 1,5-Diynes by an Acid-Mediated Allylic Rearrangement.

Abstract The first synthesis of cis -enediynes 11 from 1,5-diyne 7 is achieved by treatment with 1 equivalent of CSA in CH 2 Cl 2 at 20 °C in the presence of ROH or RSH to provide 11 as the major products in good yield. An 11-membered ring enediyne 15 was prepared similarly in 47% yield.