Reactivity of vinyl sulphonic esters. Part VII. Assisted and unassisted SN1-type reactivity of β-arylthiovinyl sulphonic esters

Abstract

The large difference in reactivity and substituent effects on rate observed in unimolecular reactions of trans-1-aryl-2-arylthiovinyl and trans-1-aryl-2-arylthiopropenyl 2,4,6-trinitrobenzenesulphonates is discussed as evidence of a different degree of anchimeric assistance due to the β-sulphur on changing the β′-group from methyl to hydrogen. Such effects, in the series of β-arylthiovinyl trinitrobenzenesulphonates so far investigated, R′(ArS)C:C{O·SO₂·-C₆H₂(NO₂)₃}Ar, increase in the order R′= H Ph < Me. The possible reasons for the observed trend are briefly discussed.