Visible Light Mediated Trifluoromethylation Of Enamines With CF₃SO₂Na

Enamines are a kind of important organic synthons,which widely exist in the bioactive natural products and drug molecular skeletons.Due to the delocalization and conjugation of lone pair electrons on nitrogen atom,the double bond of enamine has unique chemical reaction properties compared with common olefins.Enamine is an important raw material for the synthesis of various organic amines and nitrogen-containing heterocyclic compounds.In addition,because the introduction of trifluoromethyl can change the physicochemical properties and biological activities of drug molecules,trifluoromethyl organic compounds are widely used in the field of pharmaceutical chemistry.Therefore,starting from the cheap and easily available trifluoromethyl source,developing trifluoromethylation methods under mild conditions has important research significance and application potential.Focusing on the development of photocatalytic trifluoromethylation reaction,this paper successfully developed the visible light catalyzed trifluoromethylation of enamine using CF₃SO₂Na,and the reaction mechanism was investigated to understand the reaction selectivity.The main work consists of the following two parts:1、Trans trifluoromethyleneamines were obtained selectively in high yield at room temperature and in air atmosphere using cheap and easily available sodium trifluoromethylsulfite as trifluoromethylation reagent under vis ible light.The reaction has high E-selectivity and good substrate tolerance,which has potential synthetic application value.2、Based on DFT calculations,the detailed mechanism of the reaction was studied in detail.The plausible reaction mechanism was rationalized,which mainly includes the single electron redox quenching cycle of photocatalyst,the formation of trifluoromethyl radical,the addition of trifluoromethyl radical to enamine,and the deprotonation process of trifluoromethylenamine positive ion intermediate.These results could help understand the reaction mechanism,and provide an insights for the design of new reactions.