Benchmark and Solvent‐Free Preparation of Sulfonium Salt Based Electrophilic Trifluoromethylating Reagents

Abstract

Here we describe work devoted to the one‐pot preparation of electrophilic trifluoromethylating reagents. The first part describes a reappraisal of our earlier experimental conditions and leads to an improved protocol that avoids the use of solvent and allows better yields. The second part carefully studies the behavior of biaryl substrates, whose structures can drive the reaction through the formation of original noncyclic or tricyclic dibenzothiophenium salts. New compounds were tested, in a standard reaction with aniline, for their trifluoromethylating power and revealed equivalent or improved reactivity relative to that of existing reagents. Furthermore, contrary to common knowledge, the presence of electron‐donating methyl groups gave reagents with very high activity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Selective Trifluoromethylthiolation and Trifluoromethylsulfinylation of Indoles with Sodium Trifluoromethanesulfinate Promoted by Phosphorus Reagents

“…On the basis of the experimental results above and previous reports, [11][12][13][14][15]22] it can be deduced that CF 3 SCl and CF 3 SOCl are formed as key intermediates in the reaction and undergo subsequent trifluoromethylthiolation and trifluoromethylsulfinylation, respectively, with 1. It can be inferred that the formation of 2a versus 3a is a competitive process.…”

“…Previously, several mild and efficient CF 3 SN-and CF 3 SO-based electrophilic trifluoromethylthiolating reagents were developed and employed with great success in a range of trifluoromethylthiolation reactions. [13] In 2015, Zhang et al reported a CuCl-catalyzed trifluoromethylthiolation reaction of indoles by using a CF 3 SO 2 Na/ (EtO) 2 P(O)H system. [12] Sodium trifluoromethanesulfinate (CF 3 SO 2 Na), also known as Langlois reagent, and other sodium perfluoroalkanesulfinates are inexpensive and readily available commercial chemicals.…”

“…H and 19 F NMR spectroscopic data were recorded at 400 (for1 H NMR) and 376 MHz (for 19 F NMR) 13. C NMR spectroscopic data were recorded at 100 MHz.…”

One-pot synthesis of arylfluoroalkylsulfoxides and study of their anomalous 19F NMR behavior

“…When the amount of triflic acid was increased to 0.50 equiv., a doublet of doublets at À120.3 ppm with the geminal F-F coupling of 259. 9 Hz as well as two-bond H-F coupling of 55.7 Hz from one fluorine and a broad doublet at À118.4 ppm with two-bond F-F coupling from the other fluorine were seen. The diastereotopic environment for each of the two fluorine nuclei could further be altered by increasing the amount of CF 3 SO 3 H. About 5 ppm of difference between the two fluorine nuclei in chemical shift was found when 1.80 equiv.…”

“…The fluorine-containing substituents often conferred unusual physical properties and enhanced chemical reactivities [1][2][3][4]. For example, the introduction of trifluoromethanesulfinyl group into benzene resulted in S-(trifluoromethyl)-diphenylsulfonium triflates with significantly different properties and applications from its precursor [5][6][7][8][9]. Little work on arylfluoroalkylsulfoxides has been available in the literature, however.…”