Cy₂NH·HX-Promoted Cyclizations of o-(Alk-1-ynyl)benzoates and (Z)-Alk-2-en-4-ynoate with Copper Halides to Synthesize Isocoumarins and α-Pyrone

Yun Liang, Ye-Xiang Xie, Jin-Heng Li*

*Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, P. R. of China, Email: jhlihunnu.edu.cn

Y. Liang, Y.-X. Xie, J.-H. Li, Synthesis, 2007, 400-406.

DOI: 10.1055/s-2006-958960

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Abstract

Addition of a catalytic amount of Cy₂NH·HX improves the rate and yields for cyclization reactions of o-(alkynyl)benzoates in the presence of a stoichiometric amount of copper(II)halide to give 4-haloisocoumarins. Under the standard reaction conditions, various 4-haloisocoumarins are provided in good yield.

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Key Words

cyclization, o-(alk-1-ynyl)benzoate, (Z)-alk-2-en-4-ynoate, 4-haloisocoumarin, isocoumarins, 5-bromo-2-pyrone, 2-pyrones, Cy₂NH·HX, copper(II) halide

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ID: J66-Y2007-0420