Abstract:

The α-acetyl ketene dithioacetals 2,which bear various alkylthio groups,are a kind of important intermediates in organic synthesis. In this paper,dithioacetals 2 were prepared in very high yields (90%—100%) via the deacetylation reaction of the corresponding α,α-diacetyl ketene dithioacetals 1 in the presence of concentrated sulfuric acid. This reaction involves an in-situ electrophilic addition-deacetylation mechanism and shows the nucleophilicity of the α-carbon atom in α-oxo ketenedithioacetals. Meanwhile,when the reaction time was prolonged to 22—25 h,the β-keto thiolesters 3a and 3c were produced in good yields.

Key words: α,α-Diacetyl ketene dithioacetals; Concentrated sulfuric acid; Deacetylation; α-Acetyl ketene dithioacetals; β-Keto thiolesters