Acid-Catalyzed Hydrolysis of Ketene Dithioacetals and Trithioorthocarboxylates. Effect of β-Methyl Substitution

Article abstract of DOI:10.1021/jo00175a016

Hydrolysis rates of β-methyl-substituted ketene dithioacetals were measured. β-Monomethyl and β,β-dimethyl substitutions reduced the reactivity of the parent acetal by factors of 26 and 6.7 x 10⁵, respectively.Similar methyl substitutions of trithioorthoacetate, however, enhanced the hydrolysis reactivity by 3 and 23 times.The reversibility of protonation of ketene dithioacetal during hydrolysis was slightly increased by a β-methyl group, but dimethyl substitution seemed to inhibit reversibility by raising the potential barrier to protonation.