Sulfoxides, a,p-epoxy

The a,p-epoxy sulfoxides available using this protocol are important intermediates for several synthetic methodologies. For example, they give upon thermal rearrangement a, -unsaturated aldehydes and thus represent the pivotal intermediate in a two-step procedure for the one-carbon homologation of carbonyl compounds (Scheme 8). °... 

Generation of the sulfmyl carbanion of chloromethylphenyl sulfoxide (Bu"Li/THF, -78 C), followed by treatment with cyclohexanone, acetone or benzophenone, a ords the corresponding chlorohydrin (27) in good yield (68-79%). Treatment of the cyclohexanone or acetone adducts with methanolic KOH provides the a,P-epoxy sulfoxides in yields of greater than 90% (Scheme 7). Each of the halohydrin products appeared to be a single diastereomer, although the relative stereochemistry was not assigned. 

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