Efficient Syntheses of Substituted Carbazoles and Cyclopent[b]indoles from 1-Methyl-3-(benzotriazol-1-ylmethyl)indole
摘要:
1-Methyl-3-(benzotriazol-1-ylmethyl)indole (1)undergoes lithiation and 1,4-addition with a variety of alpha,beta-unsaturated ketones and aldehydes. Subsequent treatment with an acidic resin in refluxing 1,4-dioxane causes intramolecular cyclization followed by aromatization to furnish a wide range of 1.3-di-, 2,3-di- and 1,2,3-trisubstituted carbazoles 6a-j and 8 in moderate to excellent yields. NMR study is described to discriminate between structures of types 6 and 8 on the basis of H-1-C-13 long-range correlation. Treatment of 1 with styrenes in the presence of zinc bromide results in formal [3+2] cycloaddition to give cyclopent[b]indoles 14a-c in good yields. When 1 is first lithiated and reacts with electrophiles, the resulting alkylation products undergo similar [3+2] additions with styrenes to give 1-functionalized cyclopent[b]indoles 15 and 16 with a high degree of stereoselectivity.
Iodine-Catalyzed Regioselective Synthesis of Diphenyl-Substituted Carbazoles via [4 + 2] Annulation of β-Formyl Ketones with Indoles
作者:Sundaram Suresh、Hung-Sheng Chien、Chao-Hua Chen、Hao-Yu Tsai、Dai-Ru Chung、Veerababurao Kavala、Ching-Fa Yao
DOI:10.1021/acs.joc.3c01857
日期:2023.12.15
β-formyl ketones with an indole has been developed for the regioselective synthesis of diphenyl-substituted carbazoles in the presence of a catalytic amount of iodine. The 1,4-dicarbonyl compound containing a phenyl group at the α-position of an aldehyde group reacts more readily with indoles to form carbazolederivatives. Using this method, a variety of carbazolederivatives can be readily accessed