Potassium aryltrifluoroborates

Figure 3.36. Scope of Rh/(i )-binap-catalyzed asymmetric 1,4-addition of potassium aryltrifluoroborates to acyclic a,P-enamides.

Molander, G. A., Biolatto, B. Efficient Ligandless Palladium-Catalyzed Suzuki Reactions of Potassium Aryltrifluoroborates. Org. Lett. 2002,... 

Potassium aryltrifluoroborates proved to be useful candidates for microwave-promoted Suzuki reactions in aqueous environments (Scheme 1.67). ... 

Wu J, Zhang L, Luo Y (2006) Rh(I)-catalyzed cross-coupling reactions of alkenyl tosylates with potassium aryltrifluoroborates. Tetrahedron Lett 47 6747-6750... 

Recently, Zhang and coworkers reported a direct palladium-catalyzed C-2 arylation of indoles with potassium aryltrifluoroborate salts [204]. Remarkably, the direct arylation took place at room temperature when acetic acid was used as the solvent. 

Table 13. Synthesis of biatyls from diaryliodonium salts and potassium aryltrifluoroborates [52]...

The use of potassium aryltrifluoroborate salts as useful bench-stable alternatives to arylboronic acids has been demonstrated in O—H bond arylations (vide supra),... 

Scheme 7.5 Cross-coupling reaction between aryidiazonium tetrafluoroborates 7 and potassium aryltrifluoroborates 8 using two different catalytic species.

SCHEME 19.4S Suzuki reactions from potassium aryltrifluoroborates (1999). 

Figure 4.6 A cross-section of results for the oxidative direct C(sp )-H approach to orfho-arylated phosphonic monoesters using potassium aryltrifluoroborates as reported by Meng and Kim [14].

The advantage of this method was the low cattilyst loading involved. In fact, just 0.25 mol% of rhodium dimer catalyst afforded the expected benzophenone with full conversion (see Scheme 7.16). So, a straightforward synthetically useful route to congested benzophenone frameworks starting from readily available aryl aldehydes and potassium aryltrifluoroborates was described. Neutral conditions allow the direct formation of di-, tri-, and even tetra-orf/ro-substituted benzophenones under operationally simple conditions in very good yields, thanks to the use of a stable phosphonium salt of P(fBu)3. 

Thiophenediazonium salts 163 can be utiUzed as electrophilic coupling partners for differently functionaUzed alkenes 164 via a Matsuda-Heck (Scheme 64, left) as well as various potassium aryltrifluoroborates via Suzuki-Miyaura (Scheme 64, right) cross-coupling reactions giving rise to 3-substituted thiophenes 165 and 166... 

Vedejs, E., Chapman, R. W., Fields, S. C., Schrimpf, L. S. 1995. Conversion of arylhoronic acids into potassium aryltrifluoroborates—Convenient precursors of arylhoron difluoride Lewis-acids. J. Org. Chem. 60 3020-3027. 

Molander, G. A. Ellia, M. D. 2006. Suzuki-Miyaura cross-coupling reactions of benzyl halides with potassium aryltrifluoroborates. 7. Org. Chem. 71 9198-9202. 

The scope and generality of the one-pot protocol to synthesize arylboronic acids and potassium aryltrifluoroborates are summarized in Tables 4 and 5, respectively. 

Potassium aryltrifluoroborate salts are excellent coupling partners for free or protected NH-indoles at the C-2 position the palladium- and copper-catalyzed transformation takes place under mild conditions, in air, at room temperature. Furthermore, conditions were developed for the coupling of indoles with aryl boronic acids, employing Pd(OAc)2 as the catalyst and a copper salt or O2 as the oxidant. ... 

Scheme 26 Copper acetate-catalyzed coupling of arylboronic acids or potassium aryltrifluoroborate salts with N-nucleophiles...

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