Potassium vinyltrifluoroborate

Suzuki and other couplings. This Suzuki coupling has been applied to preparation of 2- and 4-arylpyridines. For a synthesis of styrenes the coupling of arenediazonium salts with potassium vinyltrifluoroborate has been developed. The latter is a. stable and efficient vinylating agent. 

Fig. 2 Proposed reaction mechanism for the synthesis of trifluoromethylated alkenes from potassium vinyltrifluoroborates by photoredox catalysis. Reproduced from ref. 87 with permission from The Royal Society of Chemistry.

Recently, Nobile and coworkers reported a synthesis of polyfluorenylenevinylenes 234, a potential material in active layers in light-emitting diodes (LEDs) [121]. In this Suzuki/Mizorold-Heck protocol, potassium vinyltrifluoroborate reacts first with 233 in the presence of Pd(PPh3)4 as catalyst and K2CO3 as base. Although most of the solvent systems tested did not promote polymerization, up to 77% of the desired polymer were obtained when using dioxane under reflux (Scheme 8.59). 

Alkenyl derivatives of selenium and tellurium vere synthesized in the reaction of diphenyl dichalcogenides and potassium vinyltrifluoroborates in good yields in the case of krfL, while only 45-53% yields were found in the case of Alk2Se2 (Scheme 3.52) [91]. This catalytic reaction did not require an addition of base. 

On the other hand, vinylBhg was disearded for the 100 g seale synthesis of the latex monomer HESS (4-hydroxyethylsulfonylstyrene, Seheme 3.22), because the Suzuki-Miyaura reaction with the aryl bromide was found to be capricious. Commercial potassium vinyltrifluoroborate was ultimately chosen despite the added cost. 

Yasu Y, Koike T, AMta M (2013) Visible-light-induced synthesis of a variety of trifluoro-methylated alkenes from potassium vinyltrifluoroborates by photoredox catalysis. Chem Commun 49 2037-2039. doi 10.1039/c3cc39235j... 

Figure 4.24 (a) C-H arylation of potassium vinyltrifluoroborate and with benzhydroxamates (b) Buchwald-Hartwig coupling/oxidation... 

As mentioned in the previous section, trifluoromethylated alkenes are promising building blocks for pharmaceuticals, agrochemicals, and functional materials [112-116]. But reported synthetic methods via trifluoromethylation exhibited limited substrate scopes with respect to hetero-aromatics and functional groups [117-121]. We found that application of potassium vinyltrifluoroborates 23, which are regarded as electron-rich alkenes, to our photocatalytic oxytrifluoro-methylation leads to efficient formation of trifluoromethylated alkenes 24 via deboronation. We revealed that our photoredox-catalyzed protocol for construction of Caikenyi-CF3 bonds exhibits broad scope in an efficient and stereoselective manner. 

Parsons AT, Senecal TD, Buchwald SL (2012) Iron(II)-catalyzed trifluoromethylation of potassium vinyltrifluoroborates. Angew Chem Int Ed 51 2947-2950... 

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