Improved Synthesis and Reaction of 11‐Chloroneocryptolepines,Strategic Scaffold for Antimalaria Agent,and Their 6‐Methyl Congener from Indole‐3‐carboxylate |
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Authors: | Li Wang Wen‐Jie Lu Tomohito Odawara Ryuhei Misumi Zhen‐Wu Mei Wei Peng Ibrahim El‐Tantawy El‐Sayed Tsutomu Inokuchi |
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Institution: | 1. Division of Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan;2. Chemistry Department, Faculty of Science, El Menoufeia University, Shebin El Koom, Egypt |
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Abstract: | Various 11‐chloro‐5‐methyl‐5H‐indolo2,3‐b]quinolines (neocryptolepines) with different substituents on the quinoline ring, key intermediates for antimalaria agents, are prepared from the substituted N‐methylanilines, easily accessible by the N‐methylation of anilines, and indole‐3‐carboxylate as a counterpart. This protocol is benign in terms of the reduced number of steps to reach the target, compared with the known method using anilines, and easy product purification. Alternatively, their 6‐methyl congener is prepared by N‐methylation of the indole moiety of 2‐arylaminoindole‐3‐carboxylate followed by successive cyclization and chlorination. 11‐Chloroneocryptolepines are found more reactive than their 6‐methyl congener in the nucleophilic substitution at the C11 position. |
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