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A new entry to synthesis of neocryptolepine related skeletons. An unexpected behavior of 3-acety-2-ethoxyindole and isatins

Author:
Gao, Wentao, Fu, Xinbo, Zhang, Xiaofei, Zhao, Yannan, Wang, Dongfang, Li, Yang
Source:
Tetrahedron letters 2016 v.57 pp. 4145-4148
ISSN:
0040-4039
Subject:
alkaloids, chemical reactions, chemical structure, ethanol, heat, potassium hydroxide, quinolines, solvents, toxicity
Abstract:
An unexpected and intriguing reaction to the direct construction of indolo[2,3-b]quinoline ring system of neocryptolepine analogues was discovered through simple heating of 3-acetyl-2-ethoxyindole with isatins in 10% aqueous ethanol media with the presence of KOH as the base. The process is very clean and avoids the use of toxic organic solvent, thereby enhancing the greenness of the transformation. Moreover, the newly-synthesized compounds bearing a pendant carboxyl group at the C-11 position of indolo[2,3-b]quinoline skeleton could be potentially applied as useful synthetic building blocks for more complex indolo[2,3-b]quinoline alkaloid derivatives.
Agid:
5516286