The reaction of acyl isothiocyanates with b-dicarbonyl compounds is thoroughly studied nowadays [1-10]. In a wide range of reaction conditions the process proceeds as C- thiocarbamoylation of the dicarbonyl component. For instance, C-thiocarbamoylated derivatives of 1, 3-cyclohexanedione [7] or dimedone [8, 9] formed in good yields at boiling reagents in dioxane or acetone. We found reaction conditions where the character of the ...