Thioxopyridinecarbonitrile as a precursor for thieno- and pyrazolopyridines

ABSTRACT

Pyridinethione 1 reacted with alkyl halides or with aliphatic alpha halocarbonyl to yield the corresponding alkylthio- derivatives 4[a-e], which underwent ring closure to form derivatives 5[a-e] Pyridinethione 1 reacted with bromomalononitrile, to give the thieno [2,3-b] pyridine-2,2-dicarbonitrile derivatives 6. Compound 1 reacted with bromomalononitrile to yield structure 7, which was elucidated by the reaction of bromomalononitrile with 8 to furnish compound 9. Treatment of each of 4[b] and 11[13] with hydrazine hydrate, respectively, afforded 3-amino-4-[4-chlorophenyl]-6-phenyl-1 H-pyrazolo [3,4-b] pyridine-5-carboxanilide [12] and ethyl 3-amino-4-[4-chlorophenyl]-6-methyl-lH-pyrazolo[3,4-b] pyridine-5-carboxylate [13], respesctively