19020-41-8Relevant academic research and scientific papers
Generation and Rearrangement of 4aH-carbazoles
Kulagowski, Janusz J.,Moody, Christopher J.,Rees, Charles W.
, p. 2725 - 2732 (2007/10/02)
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-?-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.
