A new method for synthesis of allenes, including an optically active form, from aldehydes and alkenyl aryl sulfoxides by sulfoxide–metal exchange as the key reaction and an application to a total synthesis of male bean weevil sex attractant

The sulfoxide–metal exchange reaction of β-acetoxy sulfoxides or β-mesyloxy sulfoxides, which were derived from alkenyl aryl sulfoxides and aldehydes in two steps, with a Grignard reagent or alkyllithium at low temperature gave allenes in good yields. Optically active allenes were synthesized starting from optically active 2-substituted ethenyl p-tolyl sulfoxides. A synthesis of (−)-methyl (E)-2,4,5-tetradecatrienoate, a male bean weevil sex attractant, was realized by this method.