Mn(III)-Mediated Radical Cyclization of o-Alkenyl Aromatic Isocyanides with Boronic Acids: Access to N-Unprotected 2-Aryl-3-cyanoindoles

Lu Liu, Lei Li*, Xin Wang, Ran Sun, Ming-Dong Zhou and He Wang*

*School of Petrochemical Engineering, Liaoning Petrochemical University, Fushun 113001, P. R. China, Email: lilei0814.com163.com, heliwang123126.com

L. Liu, L. Li, X. Wang, R. Sun, M.-D. Zhou, H. Wang, Org. Lett., 2021, 23, 5826-5830.

DOI: 10.1021/acs.orglett.1c01979

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Abstract

A Mn(III)-mediated radical cascade cyclization of o-alkenyl aromatic isocyanides with boronic acids provides N-unprotected 2-aryl-3-cyanoindoles. A possible mechanism involves a sequential intermolecular radical addition, intramolecular cyclization, and cleavage of a C-C bond under mild reaction conditions. Either H₂O or O₂ acts as the oxygen source for the elimination of benzaldehyde.

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proposed mechanism

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Key Words

indoles, manganese compounds

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ID: J54-Y2021