Benzylic Brominations with N-Bromosuccinimide in 1,2-Dichlorobenzene: Effective Preparation of (2-Bromomethyl-phenyl)-Methoxyiminoacetic Acid Methyl Ester

Abstract

The benzylic bromination of methoxyimino-o-tolyl-acetic acid methyl ester (1) into (2-bromomethyl-phenyl)-methoxyimino-acetic acid methyl ester (2) using N-bromosuccinimide in the presence of 2,2'-azobisisobutyronitrile in various reaction solvents were investigated. The efficiency of the reaction was found to be sensitive to the kind of reaction solvents. We found the benzylic bromination of 1 to 2 can be performed in 1,2-dichlorobenzene as reaction solvent superior to the classic Wohl-Ziegler procedure in both reaction time and isolated yield (8 h vs 12 h, 92 vs 79%). This system provides clean, rapid, and high-yielding reactions with replacement of conventional solvents, such as tetrachloromethane, by less-toxic 1,2-dichlorobenzene. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licences/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Figure 1. Synthetic route for (2-bromomethyl-phenyl)-methoxyimino-acetic acid methyl ester (2) by the Wohl-Ziegler bromination of methoxyimino-o-tolyl-acetic acid methyl ester (1) in CCl4 solvent.