Shuai Huang, Zhanjiang Zheng, Yu-Ming Cui
Aug 22, 2019
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Synthesis
Abstract
Abstract A convenient and efficient three-step synthesis of 2-(2,2-difluoroethoxy)-6-(trifluoromethyl)benzenesulfonyl chloride, the key building block of penoxsulam, is described. The main features of the synthesis include a regioselective lithiation and subsequent electrophilic substitution starting from commercially available 3-bromobenzotrifluoride to provide (2-bromo-6-(trifluoromethyl)phenyl)(propyl)sulfane, then a copper-catalyzed C–O coupling to introduce the difluoroethoxy moiety and chloroxidation conditions to give the desired sulfonyl chloride.