Electrochemical Decarboxylative Trifluoromethylation of Cinnamic Acids Revisited: A Combined Experimental and Computational Study.

Abstract

beta-(Trifluoromethyl)styrenes are potentially useful building blocks for the synthesis of organofluorine compounds because their electron-deficient C=C double bonds can undergo diverse transformations. One of the most practical methods for preparing b-(trifluoromethyl)styrenes is the decarboxylative trifluoromethylation of readily available cinnamic acid derivatives using the Langlois reagent as a less expensive trifluoromethyl source. We revisited the electrochemical decarboxylative trifluoromethylation of cinnamic acid derivatives to identify modified conditions that reduce the loading of the Langlois reagent without additional additives. The reaction mechanism was computationally investigated to gain insight into the dependence of the product yields on the aryl terminal groups. The synthetic utility of the obtained b-(trifluoromethyl)styrenes was demonstrated by their transformation into 4-aryl-3-(trifluoromethyl)pyrrolidines.