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Lactonization of 2-Alkynylbenzoates for the Assembly of Isochromenones Mediated by BF3·Et2O

Xiang Zhang, Xintong Wan, Ying Cong, Xiaohua Zhen, Qiao Li, Daisy Zhang-Negrerie, Yunfei Du*, Kang Zhao*

*School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China, Email:,

X. Zhang, X. Wan, Y. Cong, X. Zhen, Q. Li, D. Zhang-Negrerie, Y. Du, K. Zhao, J. Org. Chem., 2019, 84, 10402-10411.

DOI: 10.1021/acs.joc.9b01601

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A BF3·Et2O-mediated 6-endo-dig cyclization process enables a general and efficient lactonization of readily available 2-alkynylbenzoates to provide biologically important isochromenones under mild conditions. An alternative mechanistic pathway in which BF3·Et2O activates the carbonyl of the ester moiety, rather than the alkyne triple bond, is postulated.

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ID: J42-Y2019