Benzofurazan N-oxides as synthetic precursors. Part 2. Conversion of benzofurazan N-oxides into 2H-benzimidazoles and some unusual reactions of 2H-benzimidazoles
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 5,p. 470-478
- https://doi.org/10.1039/p19770000470
Abstract
Benzofurazan N-oxides react with primary nitroalkanes to give 1-hydroxybenzimidazole 3-oxides; with secondary nitroalkanes, red 2,2-dialkyl-2H-benzimidazole 1,3-dioxides are formed. The 2H-benzimidazole oxides react as bis-1,3-dipolar nitrones with acetylenic dipolarophiles (methyl acetylenedicarboxylate and benzyne) but undergo a complex series of redox reactions with tetracyanoethylene giving purple quinonoid dicyanomethylene derivatives, also formed by the action of the malononitrile anion. O-Alkylation of the 2H-benzimidazole oxides occurs with methyl fluorosulphate, and irradiation results in rearrangement to O-2-nitrophenylhydroxylamine derivatives.Keywords
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