Free radical catalysed additions to the double bond of diketene: a synthesis of novel oxetan-2-ones

Abstract

Free radical-catalysed additions to the exocyclic double bond of diketene are described. Thiols give unstable 4-thiomethyloxetan-2-one adducts which could be oxidised to their more stable sulphoxides or sulphones. Addition of a range of P–H compounds led, with a few exceptions, to stable phosphorus-substituted 4-methyloxetan-2-ones. The radical-catalysed chlorination of diketene by sulphuryl chloride has been shown to give 4-chloro-4-chloromethyloxetan-2-one. Further 4-halogeno-oxetan-2-ones were prepared by addition of halocarbons such as carbon tetrachloride, bromotrichloromethane, and carbon tetrabromide and of trichloromethanesulphenyl chloride to diketene.