Electrophilic Trifluoromethylating Reagent

1-Trifluoromethyl-3,3-dimethyl-1,2-benziodoxole (1) is a hypervalent iodine compound used for electrophilic trifluoromethylation developed by Togni and co-workers. 1 reacts with β-keto esters and α-nitro esters to introduce a trifluoromethyl group on their α-carbons. 1 also reacts with thiols and primary- and secondary phosphines to generate trifluoromethyl sulfides and trifluoromethyl substituted phosphines respectively. 1 is a useful trifluoromethylating reagent which can be applicable to various substrates.

Typical Procedure: ^1a)
To a vigorously stirred suspension of Ethyl 1-oxoindane-2-carboxylate (0.041 g, 0.2 mmol), K₂CO₃ (0.083 g, 0.6 mmol, 3.0 eq.), and n-Bu₄NI (0.0074 g, 0.02 mmol, 10 mol%) in MeCN (2 mL), solid 1 (0.099 g, 0.3 mmol, 1.5 eq.) was added at ambient temperature. After the mixture had been stirred for 28 h, saturated aqueous NaHCO₃ was added. Extraction of the aqueous phase three times with EtOAc, drying with MgSO₄ filtration, and evaporation of the solvent under reduced pressure yielded a brownish oil. After purification by chromatography (silica gel 60; eluent: hexanes/EtOAc (25:1)) Ethyl 1-oxo-2-trifluoromethylindane-2-carboxylate (0.036 g, 0.135 mmol, Y. 67%) was obtained as a colorless oil.