Decarboxylative and Denitrative Trifluoromethylation for the Synthesis of C_vinylCF₃ Compounds with Togni (II) Reagent

Abstract

Ah ighly efficient dimethylformamide (DMF)-promotedd ecarboxylativet rifluoromethylation of a,b-unsaturated carboxylic acids with Togni (II) reagent under metal-freec onditions has been developed. Ther eactions showed good yields,h igh stereoselectivitiesa nd excellent functional group tolerance.M echanistic studies confirmed that freeradical processes were involvedi nt his system since the CF 3 radical had been clearly trapped by scavengers.T his method has been extended to the denitrative trifluoromethylation of b-nitrostyrenes in the presence of an iron(III) catalyst.

Synthesis of Trifluoromethylthiolated Alkenes and Ketones by Decarboxylative Functionalization of Cinnamic Acids

“…More specifically, its application on the syntheses of fluorine‐containing molecules has attracted much attention during the past decades . For example, the decarboxylative trifluoromethylation has been well achieved by Hu, Liu, Maiti, Zhu, Duan, Cai, and Altman using various trifluoromethylation reagents . However, compared to large number of reports on decarboxylative trifluoromethylation, the reports on decarboxylative trifluoromethylthiolation are very rare.…”

Iron‐Promoted Radical Reactions: Current Status and Perspectives

“…Yi and coworkers have reported ad enitrative trifluoromethylation process that uses Fe(acac) 3 (1 equiv) and the Togni reagent (11; 1equiv) in DMFat1 20 8C(Scheme 24). [52] In the presence of radical scavenger TEMPO (3 equiv), the reaction was not promoted.H owever,the iron(III) salt was not responsible for the generation of the CF 3 radical;t he reaction was probably started by decomposition of the Togni reagent, which was induced at high temperature. After the addition of the CF 3 radicalt ot he nitroalkene, the iron(III)s alt oxidized the radicali ntermediate, therebya llowing the expulsion of NO 2 ,i n as imilar manner of the last step of the type Dm echanism.…”

Recent Advances of Cinnamic Acids in Organic Synthesis

“…About half of this review is devoted to these radical addition. A high temperature was good for the E configuration of alkenes . Furthermore, the cascade could involve a cyclization or oxidative coupling to get epoxides, ketones or furans (Scheme ).…”

“…Mao and co‐workers reported the decarboxylative methylation of cinnamic acids. The DTBP was employed not only as the oxidant, but also as the methyl source.C vinyl −CF 3 compounds (like Panomifene, and Cyhalothrin) were useful in medicinal chemistry . Hence, numerous efforts have been devoted to the preparation of these compounds.…”