Intramolecular cyclization of 2-(heteroarylsulfanyl)- N -(3-oxoalkenyl)acetamides: synthesis of 3-(heteroarylsulfanyl)- and 3-sulfanylpyridin-2(1 H )-ones

The reaction of 2-chloro-N-(3-oxoalkenyl)acetamides with 1,3-benzothiazole-2(3H)-thione, 1,3-benzoxazole-2(3H)-thione, and 1-methyl-1,3-dihydro-2H-benzimidazole-2-thione led to the formation of 2-(heteroarylsulfanyl)-N-(3-oxoalkenyl)acetamides. By the action of a base, these compounds were converted into pyridin-2(1H)-ones containing a divalent sulfur atom in position C-3 bonded to a heterocyclic ring. Bromination, nitration, alkylation of 3-(1,3-benzothiazol-2-ylsulfanyl)pyridin-2(1H)-ones have been studied. The action of zinc in acetic acid transformed these compounds into 3-sulfanylpyridin-2(1H)-ones.