Nickel(0)-Catalyzed Fluoroalkylation of Alkenes, Alkynes, and Aromatics with Perfluoroalkyl Chlorides

Abstract

Treatment of perfluoroalkyl chlorides (R(F)Cl) with alkenes, alkynes, or aromatics in the presence of 0.1 equiv of nickel dichloride, 1.5 equiv of zinc powder, and 0.4 equiv of triphenylphosphine in DMF at 95-100 degrees C for 6-8 h give the corresponding perfluoroalkylated products in good yields. A single electron-transfer mechanism is suggested.

Palladium-Catalyzed Heck-Type Difluoroalkylation of Alkenes with Functionalized Difluoromethyl Bromides

“…To our delight, a 41% yield (determined by 19 F NMR analysis) of the desired product 3a was observed when the reaction was conducted with Pd(OAc) 2 (10 mol%), Xantphos (20 mol%), and Cs 2 CO 3 (2.0 equiv) in 1,4-dioxane at 80 °C (Table 1, entry 1). It was found that the reaction was very sensitive to the phosphine ligands.…”

“…It was found that when a reaction mixture of 1a and 2a in the presence of PdCl 2 (MeCN) 2 (10 mol%), Xantphos (20 mol%), and K 2 CO 3 in 1,4-dioxane was treated with an ET scavenger 1,4-dinitrobenzene 19 or a radical inhibitor hydroquinone, the yield of 3a was significantly decreased, thus implying that a SET pathway via an ethoxycarbonyldifluoromethyl radical, was involved in the catalytic cycle. …”

“…Instead, fluorinated alkene 3a was observed in 9% yield (determined by 19 F NMR). This finding is in sharp contrast to the result shown in Table 1 entry 7, because if the possibility that the formation of fluorinated alkenes via sequential bromine atom transfer radical addition to alkenes, followed by base-assisted elimination of the resulting benzyl bromides is feasible, some compound 11 should be observed in the absence of base.…”

“…1 H NMR and 13 C NMR spectra were recorded on a Bruker AM 400 and AM 500 spectrometer. 19 F NMR spectra were recorded on a Bruker AM 400 spectrometer (CFCl 3 as an external standard and low field is positive). Chemical shifts (δ) are reported in ppm, and coupling constants (J) are given in hertz (Hz).…”

Reaction of Alkynes

“…Some nickel(0) complexes, generated by the reduction of NiCl 2 with Zn, catalytically promote the addition of perfluoroalkyl groups to the terminal carbon of alkynes (Table 4.9) [54]. The mechanism utilized is not clear, although the involvement of a single electron transfer has been suggested.…”