A highly efficient room temperature non-organometallic route for the synthesis of α,β,β-trifluorostyrenes by dehydrohalogenation

An efficient dehyrohalogenation method for the synthesis of α,β,β-trifluorostyrenes, α-chloro-β,β-difluorostyrenes and E-1-arylperfluoroalkenes

“…Dehydrofluorination of 1-aryl-1-chloro-2,2,2-trifluoroethanes to corresponding 1-chloro-2,2-difluorostyrenes All styrenes gave satisfactory 19 F, 1 H, 13 C NMR, GC-MS and HRMS consistent with assigned structure and are in agreement with samples prepared in our laboratory by other methods[22,25].Scheme 2. Dehydrohalogenation of PhCHClCF 3 and PhCHClCF 2 Cl using DBU.…”

“…Dehydrofluorination of 1-phenyl-1,2,2,2-tetrafluoroethane was attempted using various bases, and lithiumhexamethyldisilazide was found to be the best, 91% yield ( 19 F NMR) of 1,2,2-trifluorostyrene [25]. After standardizing the reaction conditions for the dehydrofluorination using the disilazide base, we have performed reactions for the synthesis of a series of substituted 1,2,2-trifluorostyrenes.…”

“…One such method was a dehydrohalogenation process, where dehydrofluorination or dehydrochlorination of the corresponding fluorinated precursors by a selective base could lead to TFS or related olefins. In a previous communication, we demonstrated that bases like lithiumhexamethyldisilazide (LHMDS) or DBU were excellent for effecting this transformation without undergoing the normally observed side reactions, the addition or addition-elimination with the product olefin [25]. Herein, we describe the full account of this dehyrohalogenation strategy for the synthesis of various substituted 1,2,2-trifluorostyrenes, 1-chloro-2,2-difluorostyrenes and (E)-1-arylperfluoroalkenes.…”

Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

“…In the absence of Pd(PCy 3 ) 2 , 15g was obtained in 30% yield at 60 °C for 6 h, which indicated that the palladium-catalyzed coupling reaction proceeded much faster than the background reaction. The use of perfluoronaphthalene (16) and perfluorobiphenyl (17) allowed the reaction with 4g to give 2-(4-MeOC 6 H 4 )C 10 F 7 (18g) and 4'-(4-MeOC 6 H 4 )C 12 F 9 (19g) in 53% and 32% yields, respectively. In contrast, the reaction of perfluoropyridine (20) with 4a afforded a mixture of tetrafluoro-4-phenylpyridine (21a) and tetrafluoro-2-phenylpyridine (21a') in 65% and 17% yields, respectively.…”

“…Nevertheless, conventional methods for their preparation have thus far not been fully established. For instance, most of the initial preparation routes for trifluorostyrenes required multistep reactions [13][14][15][16]. A few reactions substituting the fluorine atom on fluoroolefines, including tetrafluoroethylene (1; TFE), with a carbon nucleophile are considered classic procedures [17][18][19][20][21][22][23].…”