Reactions of trifluoromethyl bromide and related halides: part 10. Perfluoroalkylation of aromatic compounds induced by sulphur dioxide radical anion precursors

Abstract

Perfluoroalkylation of electron-rich aromatic compounds with trifluoromethyl bromide, or long-chain perfluoroalkyl iodides, was performed in the presence of sodium dithionite or zinc-sulphur dioxide. This alkylation occurred at the ortho and para positions relative to the amino or hydroxy substituent. Pyrroles were perfluoroalkylated regioselectively at the 2-position. This alkylation was interpreted as a radical aromatic substitution; the formation of the perfluoroalkyl radical can be induced by a single-electron transfer from sulphur dioxide radical anion to the perfluoroalkyl halide.

Selective fluoroalkylation of thiophenols by 1,2-dibromotetrafluoroethane activated by sulfur dioxide

“…It was demonstrated earlier [19][20][21][22][23] that sulfur dioxide can serve as an electron transfer mediator. The second aim was achieved by addition of organic nitrogen bases (such as pyridines) that increase the thiophenol nucleophility by complexation.…”

Nucleophilic trifluoromethylation of aryl halides with methyl trifluoroacetate

“…This can be done in a radical way, from CF 3 Br [3] or alkaline trifluoromethanesulfinates [4], but this technique is not regioselective, or by regioselective nucleophilic substitution of aryl iodides or bromides with (trifluoromethyl)copper(I) species, generated in situ. Several methods have been described to produce such species, either under mild conditions from ozone-depleting reagents (CF 2 Br 2 [5], CF 3 Br [6]) or expensive CF 3 I [7] and (trifluoromethyl)-trimethylsilane [8], as well as by thermal decarboxylation of alkaline trifluoroacetates in the presence of cuprous iodide [9,16].…”

Thermal Diels–Alder Reactions of 3‐(Benzoylamino)‐6‐(polyfluoroalkyl)pyran‐2‐ones – New Synthesis of p‐(Polyfluoroalkyl)anilines

“…[13] Trials to introduce a CF 3 group selectively into an aniline ring failed. [14] It is known that anilines without polyfluoroalkyl groups are available from electron-deficient 2-pyrones and electron-rich ynamines. [15] This paper reports on a new and practical method for the general and regioselective synthesis of N-benzoyl-4-(polyfluoroalkyl)anilines 5a-e by thermal Diels-Alder cycloaddition of the 2-pyrones 1a-e with the fluorostyrenes 2 and 7, the acetylenes 8a-c or vinyl ethers 10 and 13a and 13b.…”