Dithioacetal as a 1,1-zwitterion synthon. Synthesis of functionalized alkenes by the coupling of benzylic dithioacetals with another 1,1-zwitterion synthon

Reaction of a dithioacetal sequentially with BuLi and alkyl bromide having an electron withdrawing substituent at the α-position followed by treatment with neutral alumina gives the corresponding olefination product in moderate to good yields.