A novel method of indole ring system construction: One-pot synthesis of 4- and 6- nitroindole derivatives via base promoted reaction between 3-nitroaniline and ketones
作者:Nikolai Moskalev、Mieczysław Makosza
DOI:10.1016/s0040-4039(99)01014-x
日期:1999.7
Base promoted condensation of ketones RCQCH(2)R' with 3-nitroaniline results in formation of the corresponding 4- and 6-nitro-2-R-3-R'-indoles. This multistep process apparently includes oxidative nucleophilic substitution of hydrogen in the aromatic ring of the aniline by the enolate anion and subsequent cyclization of the so formed ortho-aminoketone intermediate to indoles via a Baeyer type reaction. (C) 1999 Elsevier Science Ltd. All rights reserved.
Enolizable ketones react with m-nitroaniline in the presence of strong base such as t-BuOK to give 4- and 6-substituted nitroindoles. The reaction proceeds via oxidative nucleophilic substitution of hydrogen in m-nitroaniline with enolate anions in positions ortho to the amino group giving anionic σH adducts that are additionally stabilized by intramolecular interaction between the amino and the carbonyl