Diastereofacial control in the radical addition to chiral α-sulfinyl enones

Abstract

The β-addition of alkyl radicals to chiral 2-(arylsulfinyl)-2-cyclopentenones 1 gives 3-alkyl-2-(arylsulfinyl)-1-cyclopentanones 2 with stereoselectivities depending on the bulkiness of alkyl radicals as well as the aryl sulfoxides. The X-ray analysis of the single crystal as well as the NOE experiment of 2,4,6-triisopropylphenyl sulfoxides 1d showed the effective shielding at the β position by the triisopropylphenyl group. The reaction of a diastereomeric mixture of 4-methyl-2-sulfinyl-cyclopentenones 4(S) and 4(R) gives the kinetically resolved addition product. Radical reaction of acyclic sulfinylpentenones gives abnormal Pummerer-type reaction products.