Issue 17, 2019

Oxidative oxy-cyclization of 2-alkynylbenzamide enabled by TBAB/Oxone: switchable synthesis of isocoumarin-1-imines and isobenzofuran-1-imine

Abstract

A TBAB-catalyzed oxidative 6-endo-dig oxy-cyclization of 2-alkynylbenzamide is described herein for the synthesis of isocoumarin-1-imines. The transformation proceeds regioselectively and provides the final products with high efficiency and a broad reaction scope. Interestingly, an array of isobenzofuran-1-imines is also achieved under standard conditions when N-phenyl 2-trimethylsilylethynylbenzamides are used as substrates. Mechanism studies show that 3-bromomethenisobenzofuran-1-imine is a pivotal intermediate, which goes through C–O bond migration and debromination to offer the final isocoumarin-1-imines.

Graphical abstract: Oxidative oxy-cyclization of 2-alkynylbenzamide enabled by TBAB/Oxone: switchable synthesis of isocoumarin-1-imines and isobenzofuran-1-imine

Supplementary files

Article information

Article type
Paper
Submitted
09 Feb 2019
Accepted
01 Apr 2019
First published
01 Apr 2019

Org. Biomol. Chem., 2019,17, 4335-4341

Oxidative oxy-cyclization of 2-alkynylbenzamide enabled by TBAB/Oxone: switchable synthesis of isocoumarin-1-imines and isobenzofuran-1-imine

Y. Wang, B. Ouyang, G. Qiu, H. Zhou and J. Liu, Org. Biomol. Chem., 2019, 17, 4335 DOI: 10.1039/C9OB00320G

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