Copper-Catalyzed [5 + 1] Annulation of 2-Ethynylanilines with an N,O-Acetal Leading to Construction of Quinoline Derivatives
Norio Sakai*, Kosuke Tamura, Kazuyori Shimamura, Reiko Ikeda 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. Tamura, K. Shimamura, R. Ikeda, T. Konakahara, Org. Lett., 2012, 14, 836-839.
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A novel copper-catalyzed [5 + 1] annulation of 2-ethynylanilines with an N,O-acetal gives quinoline derivatives with an ester substituent on the 2-position. A combination of CuBr2 and trifluoroacetic acid (TFA) promotes a [5 + 1] annulation of 2-ethynylaniline with ethyl glyoxylatein the presence of piperidine.
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