Investigations in the benzazole and naphthazole series

The methylation of 1-benzazolyl-3, 5-diphenylformazans (I–III) with methyl iodide takes place at the nitrogen atom of the heterocycle and the methyl derivatives obtained do not undergo oxidation to free radicals-verdazyls. On methylation with diazomethane, 1-(benzimidazol-1-yl)-3, 5-diphenylformazan (I) and 1-benzoxazolyl-3,5-diphenylformazan (III) form analogous methyl derivatives. In contrast to this, on methylation with diazomethane 1-benzothiazolyl-3, 5-diphenylformazan (II) is converted into a methyl derivative which, in benzene solution, undergoes spontaneous oxidation to 1-benzothiazolyl-3, 5-diphenylverdazyl (VII).For part XXIV, see 1].