Selective alkylation of allyl phenyl sulphone. A novel synthesis of alk-2-enes

Abstract

Treatment of the lithium salt of allyl phenyl sulphone (1) with a variety of alkyl halides affords exclusively α-alkylated products (2a–d), which are easily isomerized to (E)-αβ-unsaturated phenyl sulphones (4a–d) with catalytic amounts of t-butoxide. A new, simple method of reductive cleavage of the carbon–sulphur bonds of compounds (2)–(4) with potassium–graphite (C₈K) is described, providing a general route to alk-2-enes [(5) and (6)] in satisfactory yields.