Acid-Catalyzed Hydrolysis of a (γ-Hydroxyalkyl)ketene Dithioacetal. A Cyclic Intermediate and Product Distribution

Article abstract of DOI:10.1021/jo00384a004

2-(Hydroxyalkylidene)-1,3-dithiane 1a undergoes acid-catalyzed hydrolysis.Disappearance of 1a is faster than formation of the products thio ester 5a and lactone 5a'.The product distribution changes with pH in a similar way to that of hydrolysis of the cyclic intermediate 3a.Hydrolysis of 1a must proceed mostly through 3a, accompanying its accumulation.In comparison with the reference substrate 1b, anchimeric assistance by the internal hydroxyl group was not observed in wholly aqueous solution, but it becomes apparent in aqueous acetonitrile solutions at high organic concentration.Neighboring hydroxyl participation is considered to occur by internal solvation, and the carbocation 2a can exist as a discrete intermediate of the hydrolysis.