Synthesis of α-trifluoromethylstyrene derivatives via Pd-catalyzed cross-coupling of 2-bromo-3,3,3-trifluoropropene and arylmagnesium bromides

Synthesis of α-trifluoromethylstyrene derivatives via Ni-catalyzed cross-coupling of 2-bromo-3,3,3-trifluoropropene and aryl Grignard reagents

“…With the exception of dppp and dppb, the bidentate phosphine ligands were less effective than monodentate ligands in the coupling (entries 5, 6 and 9). Particularly, the remarkably low yield obtained with dppm is in contrast to the findings that dppm is exclusively efficient in the Pd-catalyzed coupling of BTP and PhMgBr [4]. The combination of Ni(acac) 2 and dppp or dppb gave moderate yields (entries 7 and 8) as well as NiCl 2 (dppp) and NiCl 2 (dppb) (entries 12 and 13).…”

“…It should be mentioned that byproducts formed by the cleavage of C-F bonds of a-trifluoromethylstyrene [6] were not detected [4]. Polar and basic solvents (NMP, DMPU and DMI) gave the higher yields (entries 5-7) than the other solvents commonly used in Grignard reactions (entries 1-3) and 1,4-dioxane (entry 4) in which the Pd-catalyzed coupling occurred exclusively [4]. Particularly, the use of DMI resulted in satisfactory yield (entry 7).…”

“…This Ni(II) complex exhibited the high tolerance to the substituent in the reactions with various ArMgBr. The present method will provide more versatile and economical synthesis of a-trifluoromethylstyrene derivatives than the Pd-catalyzed coupling reported previously [4]. phy was performed on silica gel (Kanto Chemical Co., N60).…”

“…With regard to the metal-catalyzed coupling for their synthesis, the Pd-catalyzed coupling of zinc or boronic acid reagents derived from 2-bromo-3,3,3-trifluoropropene (BTP) with aryl halides [2] and BTP with arylboronic acid [3] have been reported thus far. Recently, we carried out the Pd-catalyzed coupling of BTP and arylmagnesium bromides (ArMgBr) in order to demonstrate the use of more environmentally benign reagent [4]. It is well known that nickel compounds catalyze cross-coupling of vinyl halides and ArMgBr [5].…”

“…In the Pd-catalyzed coupling of BTP and ArMgBr, C-F bonds in BTP were intact [4] as well as the other Pd-catalyzed coupling [2,3].…”