Issue 0, 1985

Generation and rearrangement of 4aH-carbazoles

Abstract

The benzotriazoles (12a–c) bearing ortho-blocked 1-aryl substituents have been decomposed thermally by flash vacuum pyrolysis, and photochemically by irradiation in acetonitrile at 254 nm. The pyrolyses are complex giving mainly mono- and di-methylcarbazoles from (12a), di- and trimethylcarbazoles from (12b), and a tetra- and a penta-methylcarbazole from (12c). All of these products could be formed by generation of 4aH-carbazole intermediates (24) with subsequent thermally-allowed sigmatropic rearrangements (Scheme 6). The photolyses give a different set of products consisting mainly of the cyclopentaquinolines (27a–c) from (12a–c), respectively. These products could be formed from the same 4aH-carbazoles (24) which now undergo photochemical, aza-di-π-methane, rearrangements to give intermediates (29) and hence products (27)(Scheme 7). The 4a-methyl intermediate (29c) is intercepted as the adduct (30) in an extended cycloaddition reaction with acrylonitrile. Key reaction products were synthesized by independent methods.

Article information

Article type
Paper

J. Chem. Soc., Perkin Trans. 1, 1985, 2725-2732

Generation and rearrangement of 4aH-carbazoles

J. J. Kulagowski, C. J. Moody and C. W. Rees, J. Chem. Soc., Perkin Trans. 1, 1985, 2725 DOI: 10.1039/P19850002725

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