Reaction of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide with α, β-alkenyl carboxylic acid chlorides gave γ, δ-alkenyl α-chloro-β-keto sulfoxides in variable yields. The keto sulfoxides were also synthesized from α, β-alkenyl aldehydes in two steps in good overall yields: addition of the lithium α-sulfinyl carbanion of chloromethyl phenyl sulfoxide to α, β-alkenyl aldehydes followed by oxidation of the adducts with 2, 3-dichloro-5, 6-dicyano ...