Modified Riemschneider reaction as a new route for the synthesis of coumarinyl and 1-aza coumarinyl thioethers

Reaction of 4-thiocyanatomethyl-coumarins/1-aza-coumarins with alcohols has been investigated. In the case of primary and secondary alcohols, the reaction resulted in the formation of thiols. Reactions with tertiary-alcohols have resulted in the formation of thioethers. Structures of thermally stable thioethers have been confirmed by X-ray studies. Based on kinetic studies using fluorescence, a plausible mechanism involving decarboxylative C–S bond formation has been proposed for the modified Riemschneider reaction.