Heterocyclic transformations. Part 3. Thiolate ion-induced transformations of 6-methyl-1,3-oxazine-2,4(3H)-diones to 3-(alkyl/arylthio)but-2-enamides

Abstract

Thiolate ions generated under phase-transfer catalytic conditions react exclusively at C-6 of 3-alkyl-6-methyl-1,3-oxazine-2,4(3H)-diones to give (E)- and (Z)-3-(alkylthio)but-2-enamides. With binucleophiles having at least one thiol group, the E+Z thiobutenamides are initially formed and their further transformation depends on the nature of the second nucleophile. The bulk of the N-3 substituent of the oxazine and the thiol exercise steric control on the rate and mode of the reaction.