Investigations Concerning an Unexpected Reaction between the Dimsyl Anion (= (Methylsulfinyl)methanide) and a γ,δ-Epoxy-ketone

Article abstract of DOI:10.1002/hlca.19920750117

The reaction of 2,2-dimethyl-5-(1,2-epoxypropyl)cyclohexanone (7) with t-BuOK, in DMSO furnished a small amount of 5-(1-hydroxyprop-2-enyl)-2,2-dimethylcyclohexanone (12) and the 4 unexpected products 13-16 which contain one to three additional C-atoms (Scheme 2).The relative configuration of the major product 1-(4',4'-dimethyl-2',3'-dimethylidenecyclohexyl)propane-1,2-diol (15) was shown to be 1RS,2RS, 1'SR via NOE measurements performed on a derivative thereof.A crossover experiment in DMSO/<13C2>DMSO 1:1 as solvent showed that the two additional C-atoms of this product originate from a single molecule of DMSO (Scheme 5).A tentative mechanistic scheme, consistent with all experimental observations, is proposed which involves a <2,3>-sigmatropic corroborated part of this hypothetic scheme by taking recourse to a model compound (7-(methylsulfinyl)-p-mentha-1,8-diene (32/33), readily prepared in two steps from perilla alcohol (39)), which reacted as predicted by the proposed mechanism (Schemes 9 and 10).