Acetoxyselenenylation of Olefins for the Preparation of Vinylic and Allylic Acetates

Article abstract of DOI:10.1021/jo00265a031

Terminal and 1,2-disubstituted olefins were irreversibly acetoxyselenenylated by treatment with PhSeBr in an acetate buffer solution.Styrene derivatives yielded only Markovnikov adducts whereas simple terminal olefins and olefins containing an allylic oxygen substituent (acyloxy or aryloxy group) afforded significant amounts (50-85percent) of the anti-Markovnikov isomer.The product mixtures were isomerized to contain 90-97percent of the Markovnikov products by treatment with a catalytic amount (6-41percent) of BF3*OEt2 in chloroform.Oxidation (SO2Cl2/hydrolysis or MCPBA) of the isomerized products and selenoxide elimination at elevated temperature toward the acetoxy group afforded enol acetates in fair yields.The selenoxides of the anti-Markovnikov isomers (unisomerized mixtures) spontaneously eliminated, in the presence of the selenoxides of the Markovnikov isomer, to give allylic acetates in good yields at ambient temperature.