Hydroxythioéthers éthyléniques: synthèse et réarrangement spontané

Reactions of vinyloxiranes and thiophénols or phenylthiotrimethyl silane with ZnI 2 or n BuLi, at room temperature, were studied. These condensations proceed regio and stereospecifically to afford, in good yields, three families of hydroxy aryl ethylenic sulfides. The regiochemistry is determined by the stereochemistry, the substitution of the oxiranes, and the reaction conditions. During the condensation, 1,3 phenylthio migration occurs. Light initiates the rearrangement by bringing about cleavage of the allyl sulfur bond — a radical chain mechanism — of the hydroxy allylphenyl sulfides. Scope, rate constants, and product composition of the rearrangement were studied.