Homolysis, Oxidation, and Reduction

Homolysis, Oxidation, and Reduction.—Photolysis converts 2-nitrosoimino-3-phenyl-2,3-dihydrobenzothiazole (48 R = Ph), with loss of nitric oxide, into bis[o-(N-phenylcyanamino)phenyl] disulphide in 74% yield. Under varied conditions, 2-imino-3-phenyl-2,3-dihydrobenzothiazole is also formed (20%). The relative rates of the photolysis of (48) were measured in a number of different solvents. An interpretation of the results in terms of a free-radical mechanism involving the biradical (49) was proposed.  

In an extensive study of the selective homolytic amidation of heteroaromatic bases, the behaviour of benzothiazole has been described. Carbamoyl and a-N-amidoalkyl radicals (generated from formamide or N-alkylacetamides) attack its 2-position, producing 2-carboxamido- or 2-acetamidomethyl-benzothiazoles, generally in satisfactory yields.  

The action of peracids on substituted 2-(2-pyridyl)benzothiazoles attacks their pyridine ring preferentially subsequent cleavage of the thiazole ring results in 2-(l-oxido-2-picolinamido)benzenesulphonic acids. In contrast, pertrifluoroacetic acid oxygenates the nitrogen of the thiazole ring.  

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