Double CF Bond Activation through β‐Fluorine Elimination: Nickel‐Mediated [3+2] Cycloaddition of 2‐Trifluoromethyl‐1‐alkenes with Alkynes

Abstract

The nickel-mediated [3+2] cycloaddition of 2-trifluoromethyl-1-alkenes with alkynes afforded fluorine-containing multi-substituted cyclopentadienes in a regioselective manner. This reaction involves the consecutive two C-F bond cleavage of a trifluoromethyl or a pentafluoroethyl group through β-fluorine elimination.

Picking One out of Three: Selective Single C−F Activation in Trifluoromethyl Groups

“…A recent DFT study by Liu and Bi is in agreement with this reaction pathway . It should be noted that in the absence of Et 3 SiH, the intermediate alkenylnickel(II) fluoride complex cyclises in a 5‐ endo ‐trig fashion to yield fluorinated cyclopentadienes …”

Palladium-catalyzed allylation of trifluoromethylated ketene aminoacetals

“…d: 165.5, 161.3, 131.3, 123.6 (q, J CF = 282.8 Hz), 119. 8,68.3,58.3 (q,J CF = 25.8 Hz),54.4,53.2,35.9 (1, J CF = 1.5 Hz); EI-MS m/z: 251 (M + , 5.16), 192 (100), 45 (61), 59 (21), 69 (20), 41 (19), 82 (16) …”

“…To convert one trifluoromethyl group to another group, selective defluorination was carried out. In this paper, new CF 3 -containing nucleophilic building blocks are developed by using selective defluorination protocol [19][20][21]. By transforming one CF 3 group of 1, we obtained a group of trifluoromethylated ketene aminoacetals, which can act as nucleophile in Pd-catalyzed allylation, thus providing products with a trifluoromethylated quaternary carbon center.…”

Nickel‐Catalyzed Alkyl–Alkyl Cross‐Couplings of Fluorinated Secondary Electrophiles: A General Approach to the Synthesis of Compounds having a Perfluoroalkyl Substituent

“…(4)]. D ebromodefluorination (-BrF) [14] and hydrodebromination of the electrophile were significant side reactions.…”

“…[15] Theaddition of either NaI or NaCl also has asubstantial beneficial effect (entries 7 and 8), whereas NaF does not (entry 9). Av ariety of other ligands,b oth tridentate and bidentate,f urnish significantly lower yields compared with that obtained with the pybox ligand 1 (entries [10][11][12][13][14]. [16] Theo ptimized method is not affected by the presence of asmall amount of water (entry 15) and is only modestly sensitive to air (entry 16).…”