Chlorinative Cyclization of Aryl Alkynoates Using NCS and 9-Mesityl-10-methylacridinium Perchlorate Photocatalyst

Milan Pramanik, Ashis Mathuri, Sudip Sau, Monojit Das and Prasenjit Mal*

*National Institute of Science Education and Research (NISER) Bhubaneswar, HBNI, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Odisha 752050, India, Email: pmalniser.ac.in

M. Pramanik, A. Mathuri, S. Sau, M. Das, P. Mal, Org. Lett., 2021, 23, 8088-8092.

DOI: 10.1021/acs.orglett.1c03100

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Abstract

A chlorinative cyclization of aryl alkynoates in the presence of N-chlorosuccinimide (NCS) and Mes-Acr-MeClO₄ as photocatalyst provides 3-chlorocoumarins under visible-light irradiation. The radical initiated reaction proceeds via Cl^- addition, 5-exo-trig spirocyclization and subsequent 1,2-ester migration.

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proposed mechanism

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Key Words

coumarins, NCS, photochemistry, organocatalysis

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ID: J54-Y2021