- Redox-neutral decarboxylative photocyclization of anthranilic acids
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A mild metal-, catalyst-, and oxidant-free photoredox neutral system has been found to efficiently enable intramolecular decarboxylative cyclization of anthranilic acids. This facile protocol provides an alternative method for the synthesis of carbazoles. Mechanistic studies reveal a key photoinduced 6π-electrocyclization process and formic acid was released as the sole byproduct.
- Huang, Huawen,Deng, Kun,Deng, Guo-Jun
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supporting information
p. 8243 - 8247
(2020/12/29)
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- Generation and Rearrangement of 4aH-carbazoles
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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.
- Kulagowski, Janusz J.,Moody, Christopher J.,Rees, Charles W.
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p. 2725 - 2732
(2007/10/02)
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