Radical-nucleophilic substitution (SRN1) reactions. Part 6. N-anions of diazoles in SRN1 and oxidative additions

Abstract

The anions of imidazole, benzimidazole, 5(6)-nitrobenzimidazole, and 5(and 6)-nitro-1H-and -2H-indazoles have been shown to undergo oxidative addition to the anion of 2-nitropropane (using potassium ferricyanide and sodium persulphate), and S_RN1 reactions with Me₂C(X)NO₂(X = Cl, Br, and NO₂) to yield the corresponding 1-(1-methyl-1-nitroethyl) derivatives. The anions of 5(6)-nitrobenzimidazole and 5(6)-nitro-1H- and -2H-indazoles underwent reaction with p-nitrobenzyl chloride by a S_RN1 and/or S_N2 mechanism to yield the corresponding 1-(p-nitrobenzyl) derivatives. The ambident anions of 5- and 6-nitrobenzimidazole, 5-nitro-1H- and -2H-indazoles, and 6-nitro-1H- and -2H-indazoles gave ca. 50 : 50 mixtures of the N-1 alkylation products resulting from respective pairs of ambident anions. The 1-(1-methyl-1-nitroethyl) derivatives of benzimidazole and 5- and 6-nitro-1H-indazole underwent further substitution of the aliphatic nitro group with the respective diazole to yield 2,2-di(benzimidazol-1-yl)-, 2,2-di[5(and 6)-nitro-1H-indazol-1-yl]-propanes.