InBr3-Promoted Divergent Approach to Polysubstituted Indoles and Quinolines from 2-Ethynylanilines: Switch from an Intramolecular Cyclization to an Intermolecular Dimerization by a Type of Terminal Substituent Group
Norio Sakai*, Kimiyoshi Annaka, Akiko Fujita, Asuka Sato and Takeo Konakahara
*Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan, Email: sakachemrs.noda.tus.ac.jp
N. Sakai, K. Annaka, A. Fujita, A. Sato, T. Konakahara, J. Org. Chem., 2008, 73, 4160-4165.
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Indium-catalyzed cyclization of 2-ethynylanilines produced various polyfunctionalized indole derivatives in good yields for substrates having an alkyl or aryl group on the terminal alkyne. In contrast, substrates with a trimethylsilyl group or without substituent on the triple bond afforded polysubstituted quinoline derivatives in good yields via an intermolecular dimerization.
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