1438
T. Ito et al.
LETTER
1 M HCl (100 mL). After the usual work-up and a short
References
column chromatography of the resulting oil, 10.2 g of crude
diphenylborinic acid was obtained. To the solution of
diphenylborinic acid in MeOH (200 mL) at 0 °C, KHF2
(11.7 g, 150 mmol) was added and stirred for 1 h. The
solvent was removed in vacuo and the residual solid was
extracted with an appropriate amount of acetone, and the
organic layer was concentrated. The amount of 100 mL of
Et2O was added to the residue. The product was collected
and dried in vacuo. Potassium diphenyldifluoroborate (1a,
9.94 g) was obtained as a white powder (82% yield). Mp
211 °C (dec.), ref.9 230 °C. 1H NMR (300 MHz, DMSO-d6):
d = 7.32 (br d, 2 H, J = 6.6 Hz), 7.01 (t, 2 H, J = 7.2 Hz),
6.95–6.80 (m, 1 H). 13C NMR (75.5 MHz, DMSO-d6): d =
131.34 (t, J = 3.7 Hz), 125.87, 123.72. 19F NMR12 (254
MHz, DMSO-d6): d = –157.2 (q, J = 73.3 Hz). 11B NMR12
(86.6 MHz, DMSO-d6): d = 7.0 (t, J = 73.2 Hz). Elemental
analysis: Anal. Calcd for C12H10BF2K: C, 59.53; H, 4.16.
Found: C, 59.71; H, 4.12.
(1) For review see: (a) Miyaura, N.; Suzuki, A. Chem. Rev.
1995, 95, 2457. (b) Suzuki, A. J. Organomet. Chem. 1999,
576, 147. (c) Kotha, S.; Lahiri, K.; Kashinath, D.
Tetrahedron 2002, 58, 9633.
(2) Hassan, J.; Sévignon, M.; Gozzi, C.; Schulz, E.; Lemaire, M.
Chem. Rev. 2002, 102, 1359.
(3) Li, W.; Nelson, D. P.; Jensen, M. S.; Hoerrner, R. S.; Cai, D.;
Larsen, R. D.; Reider, P. J. J. Org. Chem. 2002, 67, 5394.
(4) Vazquez, E.; Davies, I. W.; Payack, J. F. J. Org. Chem.
2002, 67, 7551.
(5) (a) Ishiyama, T.; Murata, M.; Miyaura, N. J. Org. Chem.
1995, 60, 7508. (b) Murata, M.; Oyama, T.; Watanebe, S.;
Masuda, Y. J. Org. Chem. 2000, 65, 164. (c) Baudoin, O.;
Guénard, D.; Guéritte, F. J. Org. Chem. 2000, 65, 9268.
(6) Bumagin, N. A.; Tsarev, D. A. Tetrahedron Lett. 1998, 39,
8155.
(7) (a) Ciattini, P. G.; Morera, E.; Ortar, G. Tetrahedron Lett.
1992, 33, 4815. (b) Bumagin, N. A.; Luzikova, E. V.;
Sukhomlinova, L. I.; Tolstaya, T. P.; Beletskaya, I. P. Izv.
Akad. Nauk, Ser. Khim. 1995, 394; Chem. Abstr. 1995, 123,
285350g. (c) Bumagin, N. A.; Bykov, V. V. Zh. Obshch.
Khim. 1996, 66, 1981; Chem. Abstr. 1997, 126, 225047r.
(d) Bumagin, N. A.; Bykov, V. V. Tetrahedron 1997, 53,
14437. (e) Bumagin, N. A.; Korolev, D. N. Tetrahedron
Lett. 1999, 40, 3057.
(8) (a) Vedejs, E.; Chapman, R. W.; Fields, S. C.; Lin, S.;
Schrimpf, M. R. J. Org. Chem. 1995, 60, 3020. (b) Batey,
R. A.; Quach, T. D. Tetrahedron Lett. 2001, 42, 9099.
(c) Molander, G. A.; Biolatto, B. Org. Lett. 2002, 4, 1867.
(9) Thierig, D.; Umland, F. Naturwissenschaften 1967, 54, 563.
(10) Raction of bis(3,5-dimethylphenyl)borinic acid with vinyl
triflate was reported. See: Winkle, D. D.; Schaab, K. M. Org.
Proc. Res. Dev. 2001, 5, 450.
(11) The Representative Procedure for the Preparation of
Potassium Diaryldifluoroborates is as follows: Under an
argon atmosphere, to a solution of phenylmagnesium
bromide prepared from magnesium turnings (2.67 g, 110
mmol) and bromobenzene (18.1 g, 115 mmol) in anhyd THF
(150 mL) was slowly added triisopropyl borate (9.4 g, 50
mmol) and anhyd THF (30 mL) at 0 °C over 30 min. After
addition of triisopropyl borate, the reaction mixture was
allowed to warm slowly to r.t. and stirred at the same
temperature for 16 h. The reaction was then hydrolyzed with
(12) The B-F coupling on NMR measurement was observed at
80 °C.
(13) The Representative Procedure for the Cross-Coupling
Reaction of Potassium Diaryldifluoroborates is as
follows: Under Ar atmosphere, a solution of potassium
diphenyldifluoroborate (1a) (133 mg, 0.55 mmol),
Pd(OAc)2 (6 mg, 0.03 mmol), PPh3 (31 mg, 0.12 mmol), 1-
bromo-2-nitorobenzene (2f) (202 mg, 1.0 mmol), and
Na2CO3 (159 mg, 1.5 mmol) in 2-methoxyethanol (5 mL)
and H2O (0.5 mL) was heated under reflux. The reaction
mixture was stirred at the same temperature for 6 h and then
cooled to r.t., and acidified with 1 M HCl. The mixture was
extracted with MTBE (30 mL × 3). The organic layer was
washed with brine (30 mL) and dried over MgSO4. The
solvent was removed in vacuo, and the crude product was
purified by silica gel column chromatography to afford 2-
nitrobiphenyl (3d) (187 mg, 0.94 mmol) in 94% yield.
(14) Reaction of potassium bis(4-biphenyl)difluoroborates (1d)
and 4-chloroacetophenone (2a) afforded the coupled product
and biphenyl which resulted from potassium salt in 66% and
31% yields, respectively.
(15) A similar decomposition was reported for Ph2BOH. See:
Abel, E. W.; Gerrard, W.; Lappert, M. F. J. Chem. Soc. 1958,
1451.
Synlett 2003, No. 10, 1435–1438 © Thieme Stuttgart · New York