OXIDATION OF THIOAMIDES WITH THE DMSO–HCl SYSTEM: A CONVENIENT AND EFFICIENT METHOD FOR THE SYNTHESIS OF 1,2,4-THIADIAZOLES, ISOTHIAZOLO[5,4-<i>b</i>]PYRIDINES, AND HETEROCYCLIC DISULFIDES
DOI:
https://doi.org/10.1007/561Keywords:
cyanothioacetamide, dimethyl sulfoxide, disulfides, isothiazolo[5, 4-b]pyridines, pyridine-2(1H)-thiones, 1, 2, 4-thiadiazoles, thioamides, oxidation, oxidative dimerizationAbstract
Brief heating of 3-aryl-2-cyanothioacrylamides in the DMSO–HCl system gave (2E,2'E)-2,2'-(1,2,4-thiadiazol-3,5-diyl)bis(3-arylacrylonitriles). Under the same conditions, cyclic thioamides (derivatives of 2‑thioxo-1,2-dihydropyridine-3-carbonitrile and quinoxaline-2(1H)-thione) gave good yields of the bis(hetaryl) disulfides. Ethyl 4-(4-chlorophenyl)-5-cyano-2-phenyl-6-thioxo-1,4,5,6-tetrahydropyridine-3-carboxylate gave a mixture of oxidation products at the sulfur atom and the heterocycle when treated with the DMSO–HCl system. Oxidation of N-aryl-4,6-dimethyl-2-thioxo-1,2-di-hydropyridine-3‑carboxamides gave isothiazolo[5,4-b]pyridines.
Authors: V. V. Dotsenko and S. G. Krivokolysko
English Translation in Chemistry of Heterocyclic Compounds, 2013, 49 (4), pp 636-644
