Electrophilic trifluoromethylation of arenes and N-heteroarenes using hypervalent iodine reagents

The reaction of hypervalent iodine trifluoromethylating reagents with a variety of arenes and N-heteroarenes gives access to the corresponding trifluoromethylated compounds. In comparative studies, 1-trifluoromethyl-1,3-dihydro-3,3-dimethyl-1,2-benziodoxole (2) proved to be the superior to 1-trifluoromethyl-1,2-benziodoxol-3-(¹H)-one (1) for the direct aromatic trifluoromethylation. Depending on the individual substrates, additives such as zinc bis(trifluoromethylsulfonyl)imide or tris(trimethylsilyl)silyl chloride proved helpful in promoting the reactions. In the case of nitrogen heterocycles a pronounced tendency for the incorporation of the trifluoromethyl group at the position adjacent to nitrogen was observed.     

Electrophilic trifluoromethylation by copper-catalyzed addition of CF3-transfer reagents to alkenes and alkynes

Regio- and stereoselective Cu-catalyzed addition of the above hypervalent iodine reagent to alkynes and alkenes was achieved. In the presence of CuI, the reaction is suitable to perform trifluoromethyl-benzoyloxylation and trifluoromethyl-halogenation of alkenes and alkynes. Electron-donating substituents accelerate the process, and alkenes react faster than alkynes emphasizing the electrophilic character of the addition reaction.     

Nucleophilic trifluoromethylation of arylidenemalononitriles

A method for the nucleophilic trifluoromethylation of arylidenemalononitriles using Me₃SiCF₃ is described. The reaction is carried out in dimethylformamide in the presence of AcONa as a Lewis base, and affords products of Michael addition in high yield.     

Electrophilic trifluoromethylation of simple inorganic salts: a one step route to trifluoromethylnitromethane, CF3NO2

Trifluoromethylnitromethane is readily synthesized in high yield from the electrophilic trifluoromethylation of NaNO₂.     

Thermolytic trifluoromethylation of pentafluoropyridine

Russian Chemical Bulletin -     

Electrochemical trifluoromethylation of aromatic compounds

It was shown that the current yield of the products of anodic trifluoromethylation of arenes correlates with the adsorptivity and the rate of electrooxidation of arenes on the surface of a platinum electrode. Translated fromIzvestiya Akademi Nauk, Seriya Khimicheskaya, No. 6, pp. 1180–1184, June, 1997.     

Towards enantioselective nucleophilic trifluoromethylation

Various trifluoroacetamides and trifluoromethanesulfinamides, derived from chiral silylated amino alcohols, have been synthesized with the goal of achieving enantioselective nucleophilic trifluoromethylation. The best results were obtained with (R)-phenylglycinol derivatives, but the ee values did not exceed 30 %.     

Radical trifluoromethylation of ammonium enolates

The easy radical trifluoromethylation of a series of 1,3-dicarbonyl compounds with CF₃I is described. The reaction occurs in the presence of a nitrogen base and sodium dithionite in CH₃CN-H₂O solution. Additionally, we report a new access to ammonium triflinates.     

Nucleophilic trifluoromethylation with organoboron reagents

Potassium trialkoxy(trifluoromethyl)borates are shown to behave as convenient reagents for nucleophilic trifluoromethylation of non-enolizable aldehydes and N-tosylimines to give CF₃-substituted alcohols and N-tosylamines in good yields.     

Stereospecific conversion of cyclic phosphorothioates into chlorophosphates

The reaction of the individual diastereoisomeric cyclic phosphorothioates 2a, 2b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.4.0) decane and 4a, 4b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.3.0) nonane series with sulphuryl chloride affords the corresponding sulphenyl chlorides 5a, 5b, 6a, 6b with retention of the configuration of the phosphorus atom. The reaction of the latter with phosphorus trichloride leads stereospecifically to the chlorophosphates 7a, 7b, 8a and 8b with full retention of configuration at phosphorus.     

Visible-light-promoted and photocatalyst-free trifluoromethylation of enamides

An efficient and practical method is developed for the trifluoromethylation of enamides using Umemoto’s reagent as the trifluoromethylating reagent. These reactions proceeded under visible light irradiation without any photocatalyst at room temperature in good chemical yields.