Conjugate additions to α,β-unsaturated sulphoxides: syntheses of cyclopentenones and 9-deoxyprostanoids
Abstract
1,4- Dicarbonyl compounds, and hence cyclopentenone derivatives, were prepared by conjugate additions of enolate and related anions to α,β-unsaturated sulphoxides, followed by sulphoxide–ketone transformations. These transformations involved trapping the intermediate α-sulphinyl carbanions with dimethyl disulphide to give thioacetal monoxide derivatives, or Pummerer rearrangements of the sulphoxides to give alkenyl sulphides. 3-Substituted 2-ethoxycarbonylcyclopentenones prepared in this way were converted into 9-deoxyprostanoids and their 12-ethoxycarbonyl derivatives, the latter by use of 2-phenylsulphinyloct-1-en-3-one as an electrophilic prostanoid β-side-chain precursor.