ELECTROPHILIC ADDITIONS TO ALLENES-II; THE REACTION OF BENZENESELENENYL CHLORIDE WITH SOME 1,3-DISUBSTITUTED ALLENES

Article abstract of DOI:10.1016/S0040-4020(01)83115-X

Benzeneselenenyl chloride reacts with 1,3-dialkyl-substituted allenes in methylene chloride solution to give 1:1-adducts.Attack by selenium is found to occur exclusively at the central allenic carbon.In contrast to the analogous reaction of arenesulphenyl chlorides, the preferential formation of the Z-alkene is observed.A mechanism involving the preequilibrium formation of alkylideneseleniranium ions and/or alkylideneepiselenuranes which, in the product-determining step, collapse to products via an anti attack of chloride at the methine carbon of the ring is proposed to account for the preferential formation of the Z-isomers.