Sulfo-Biginelli reaction: an insight into interaction between sulfamides and enolizable ketones

The interaction employing sulfamide and enolizable ketones was closely inspected in Biginelli reaction. The three-component variation of the reaction ''sulfamide + ketone + anisaldehyde'' and ''sulfamide + ketone + N , N -diethylacetoacetamide'' featured a lack of selectivity and provided a mixture of possible condensation products. Selectivity was improved when ketones were used in the reaction both as carbonyl and enol components. It was shown that trimethylsilyl chloride promoted interaction of sulfamide with ketones to afford 1,2,6- thiadiazines. Limitations were noted and unpredictable outcomes of the reaction were discussed as well.