Fluorination with xenon difluoride. 21. Evidence for free-radical intermediates in trifluoroacetic acid catalyzed fluorinations

The Versatile Behavior of Platinum Alkyne Complexes towards XeF2: Formation of Fluorovinyl and Fluorido Complexes

“…The platinum center adopts as quare-planar geometry by the phosphorus atoms P1 and P2 of the dcpe ligand as well as the C33 and C36 atoms.T he Pt1ÀP1 and Pt1ÀP2 bond lengths and the bite angle are similar to the one known foro ther platinum(II) complexes with the dcpe ligand. Note that these fluorinated products can also be synthesized from tolane as starting [125][126][127][128][129] Mechanistically,w ea ssume that in af irst step the fluorido complex [Pt(PhC=CFPh)(F){k 2 -(P,P)-Cy 2 PC 2 H 4 PCy 2 }] (16)i s formed after ar eaction of the platinum alkyne complex 14 with XeF 2 (Scheme 6). Note that the cyclometalated complex [Pt(o-C 6 H 4 CF=CPh){k 2 -(P,P)-Cy 2 PC 2 H 4 PCy 2 }] (18)w as not observed in the reaction mixture with two equivalents of XeF 2 .T he organic products were separated by hexane extraction from compound 15.T he fluorinated products 1,1,2,2-tetrafluoro-1,2-diphenylethane, (Z)-1,2-difluoro-1,2-diphenylethene, and (E)-1,2difluoro-1,2-diphenylethene were formed in ar atio of 1:3.5:2.5 according to the 19 FNMR spectrum.…”

Trifluoromethylation of various aromatic compounds by CF3I in the presence of Fe(II) compound, H2O2 and dimethylsulfoxide

“…This suggests that an electron-donating character of hydroxyl group is very effective in the trifluoromethylation. Pyrimidine and pyradine derivatives also provided ortho-or para-oriented products (entries [6][7][8]. This orientation in the products suggests that the nitrogen atoms in the rings of 2-aminopyrimidine (entry 6) and aminopyradine (entry 8) were protonated by H 2 SO 4 like 2,6-diaminopyridine.…”

“…It has electrophilic nature and can be readily generated from various radical sources [1,2]. In the previous methods of radical trifluoromethylation of aromatic, heteroaromatic and pseudo-aromatic compounds, a trifluoromethyl radical is formed from CF 3 Br photochemically [3] or in the presence of Zn/SO 2 or Na 2 S 2 O 4 [4], CF 3 COOH electrochemically [5] or in the presence of XeF 2 [6], CF 3 COOAg photochemically [7], CF 3 SO 2 M (M = Na or K) electrochemically [8], bis(trifluoroacetyl)-peroxide [9] or Te(CF 3 ) 2 [10]. However, these methods seem practically unsuitable because of the reagents and/or apparatus required.…”

Strategies for nucleophilic, electrophilic, and radical trifluoromethylations

“…In 1979, Zupan reported the reaction of olefins with xenon difluoride in the presence of trifluoroacetic acid in which the Scheme formation of trifluoromethylated products was explained by the generation of the trifluoromethyl radical [147]. This species can also be electrochemically generated from trifluoroacetic acid and reacted with enolacetates and enols of 1,3-dicarbonyl compounds [148].…”