| Abstrakt: |
Ethenesulfonyl chloride (1) reacts with alcohols in the presence of tertiary amines to give a mixture of the alkyl ethenesulfonate (5) and the alkyl betylate (R3′N+CH2CH2SO2OR Cl−). With pyridine and neopentyl alcohol the product composition from the reaction of 1is identical to that from the pyridinio-sulfonyl chloride (9). These results, when taken with experiments with deuterium labelled reagents, lead to the conclusion that the major (~80%) reaction pathway involves conversion of 1or 9to the sulfene 8, which reacts with the alcohol to form 5or the betylate, and hence vinylogous nucleophilic catalysis is the major process leading to 5. The labelling experiments disclosed a minor pathway, evidently involving interconversion of 1and 9. Examination of possible mechanisms leads to the suggestion that the sulfene is formed from 1or 9by way of the carbanion (14), i.e., that 9reacts by an E1cB process, and that the minor pathway is simply the result of side reactions of the carbanion (14). Keywords: sulfenes, sulfonyl transfer mechanisms, vinylogous nucleophilic catalysis. |
