Reduction of β-arylthio- or β-alkylthio-αβ-unsaturated ketones

Abstract

The preparation and reduction of β-arylthio- or β-alkylthio-αβ-unsaturated ketones (1) with lithium aluminium hydride or sodium borohydride have been examined. Reduction of the ketones (1) with lithium aluminium hydride gave αβ-unsaturated ketones (2), in which the olefinic (R¹) and carbonyl (R²) substituents are reversed compared with the starting αβ-unsaturated ketone (1), or the saturated γ-hydroxy-sulphides (3). Reduction of the ketones (1) with sodium borohydride afforded only the αβ-unsaturated ketones (2). Reduction of (1) with sodium borohydride in the presence of metal halides gave the saturated ketones (5).