Reduction of SF₅CF₃viairidium catalysis: radical trifluoromethylation of aromatics

Abstract

The green-house gas SF5CF3 acts as CF3 source for the photocatalytic trifluoromethylation of arenes on using [Ir(dtbbpy)(ppy)2]PF6 (4,4′-di-tert-butyl-2,2′-dipyridyl, ppy = 2-phenylpyridine) as catalyst. The trifluoromethylation of C6D6 in the presence...

Activation of SF5CF3 by the N-Heterocyclic Carbene SIMes

“…Analytical data for α,α,α-trifluorotoluene-d 5 : 19 F NMR (282.4 MHz, C 6 D 6 ): δ = −62.4 ppm., GC-MS (C 6 D 6 ): calculated ( m / z ) for [α,α,α-trifluorotoluene-d 5 ]: 151, experimental ( m / z ) for [α,α,α-trifluorotoluene-d 5 ]: 151. The obtained NMR data are consistent with those in the literature [ 22 ].…”

“…Analytical data for 8: 19 F NMR (282.4 MHz, C 6 D 6 ): δ = −56.5 ppm. The obtained NMR data are consistent with those in the literature [15,22].…”

“…As mentioned above, DF can be formed in association with the photochemical trifluoromethylation of the aromatic compounds. For this process, initially a cyclohexadienyl radical via reaction with a CF 3 radical with C 6 D 6 might be generated [ 22 , 30 , 41 , 42 , 43 ]. The cyclohexadienyl radical can then transfer an electron to the SIMes radical cation, giving a cyclohexadienyl cation.…”

“…With toluene-d 8 as a solvent, the photochemical activation of SF 5 CF 3 with SIMes led to the formation of CD 3 C 6 D 5 CF 3 , although the reaction is not selective, and small amounts for unknown products can be detected in the 19 F NMR spectrum. Trifluoromethylation proceeded at the ortho (9%, NMR yield based on the consumption of SF 5 CF 3 ) and para (5%) position of toluene-d 8, but also at the meta position (4%) [22,30,31].…”

“…We previously reported on a photocatalytic reduction of SF 5 CF 3 using [Ir(dtbbpy)(ppy) 2 ]PF 6 (4,4′-di- tert -butyl-2,2′-dipyridyl, ppy = 2-phenylpyridine) as the photocatalyst and NEt 3 as the reductant. The generation of a CF 3 radical led to the development of a process for the trifluoromethylation of aromatics [ 22 ]. With regard to the activation of SF 6 , the N -heterocyclic carbene SIMes was used to achieve a photolytic activation at 311 nm, yielding 1,3-dimesityl-2,2-difluoroimidazolidin (SIMesF 2 , 2 ) and 1,3-dimesitylimidazolidine-2-sulfide.…”