Hydrophilic CNC-Pincer Palladium Complexes
COMMUNICATIONS
(2H, s, H-4’), 8.26 (2H, s, H-3, H-5), 8.61 (2H, s, H-5’);
Synth. Catal. 2005, 347, 329–338; d) F. Koc, F. Micha-
lek, L. Rumi, W. Bannwarth, R. Haag, Synthesis 2005,
3362–3372; e) D. K. Peeler, A. D. Cozzi, R. F. Schu-
macher, I. A. Reamer, R. J. Workman, Ceram. Trans.
2006, 176, 25–31; f) T. Mitsudome, T. Umetani, K.
Mori, T. Mizugaki, K. Ebitani, K. Kaneda, Tetrahedron
Lett. 2006, 47, 1425–1428; g) I. P. Beletskaya, A. N.
Kashin, A. E. Litvinov, V. S. Tyurin, P. M. Valetsky, G.
van Koten, Organometallics 2006, 251, 154–158.
[2] a) B. M. Bhanage, M. Arai, Catal. Rev. 2001, 43, 315–
344; b) M. Pagliaro, Adv. Synth. Catal. 2005, 347, 1961–
1964; c) S. Doherty, J. G. Knight, M. Betham, Chem.
Commun. 2006, 88–90; d) B. Blanco, M. Brissart, M.
Moreno-Manas, R. Pleixats, A. Mehdi, C. Reye, S. Bou-
quillon, F. Henin, J. Muzart, Appl. Catal. A 2006, 297,
117–124; e) S. H. Li, Y. J. Lin, H. B. Xie, S. B. Zhang,
J. N. Xu, Org. Lett. 2006, 8, 391–394.
[3] a) For a general review, see: C.-J. Li, Chem. Rev. 2005,
105, 3095–3165; see also: b) J. P. Genet, M. Savignac, J.
Organomet. Chem. 1999, 576, 305–317; c) D. Schön-
felder, O. Nuyken, R. Weberskirch, J. Organomet.
Chem. 2005, 690, 4648–4655; d) J.-H. Kim, J.-W. Kim,
M. Shokouhimehr, Y.-S. Lee, J. Org. Chem. 2005, 70,
6714–6720; e) K. H. Shaughnessy, R. B. DeVasher,
Curr. Org. Chem. 2005, 9, 585–604.
13C NMR
(DMSO):
d=13.68
(CH3),
19.10
(NCH2CH2CH2CH3), 32.77 (NCH2CH2CH2CH3), 49.67
(NCH2), 108.33 (C-3, C-5), 118.58 (C-5’), 124.00 (C-4’),
150.23 (C-2, C-6), 157.68 (C-4), 163.62 (CO), 165.59 (C-2’);
HR-MS: m/z= 630.9409, calcd. for C20H25Br2N5O2Pd:
630.9410; anal. calcd. for C20H25Br2N5O2Pd: C 37.91, H 3.98,
N 11.05; found: C 37.89, H 3.92, N 11.03.
General Procedure for the Suzuki–Miyaura Coupling
Catalyzed by Complex 5
Pincer complex 5 (0.1 mol% Pd) was added to a mixture of
bromoarene (1 mmol) and arylboronic acid (1.5 mmol),
K2CO3 (2 mmol) and H2O (1 mL) in a 5-mL round-bottom
flask open to the atmosphere. After stirring at 1008C for
2 h, the reaction mixture was cooled and Na2CO3 (5 mL of
10% solution in water) was added. The aqueous layer was
extracted with CH2Cl2 (3×3 mL) and the combined organic
extracts were dried over anhydrous sodium sulfate and
evaporated under vacuum. Analysis of the so-obtained resi-
1
due was performed by H NMR [using bis(ethylene glycol)-
dimethyl ether as internal standard].
Reuse of Catalyst 5 in Suzuki–Miyaura Couplings
[4] For some recent examples, see: a) F. Churruca, R. San-
Martín, I. Tellitu, E. Domínguez, Synlett 2005, 3116–
3120; b) M. Carril, R. SanMartín, F. Churruca, I. Telli-
tu, E. Domínguez, Org. Lett. 2005, 7, 4787–4789; c) F.
Churruca, R. SanMartin, I. Tellitu, E. Domínguez, Eur.
J. Org. Chem. 2005, 2481–2490.
[5] a) J. T. Singleton, Tetrahedron 2003, 59, 1837–1857;
b) I. P. Beletskaya, A. V. Cheprakov. J. Organomet.
Chem. 2004, 689, 4055–4082; c) R. Chanthateyanonth,
H. Alper, Adv. Synth. Catal. 2004, 346, 1375–1384;
d) F. E. Hahn, M. C. Jahnke, V. Gomez-Benitez, D. Mo-
rales-Morales, T. Pape, Organometallics 2005, 24, 6458–
6463.
[6] a) J. A. Loch, M. Albrecht, E. Peris, J. Mata, J. W.
Faller, R. H. Crabtree, Organometallics 2002, 21, 700–
706; b) E. Peris, R. H. Crabtree, Coord. Chem. Rev.
2004, 248, 2239–2246; c) M. Poyatos, F. Márquez, E.
Peris, C. Claver, E. Fernandez, New. J. Chem. 2003, 27,
425–431.
A
5-mL round-bottom flask was charged with ArBr
(1 mmol), ArB(OH)2 (1.5 mmol), 5 (0.001 mmol Pd), K2CO3
(2 mmol), and H2O (mL). The mixture was stirred for 2 h at
1008C in air. After cooling, the aqueous layer was extracted
with Et2O (2×3 mL) and the flask was charged again with
ArBr (1 mmol), ArB(OH)2 (1.5 mmol) and K2CO3
(2 mmol). Every time, after cooling and extraction with
Et2O (2×3 mL), the reagents and base were added and the
reaction repeated. As previously explained in the general
procedure, the combined organic extracts were dried over
anhydrous sodium sulfate, evaporated under vacuum and
the residue was analysed by NMR each time. Note: Alterna-
tively toluene was used as the extracting solvent instead of
Et2O, but due to the lower solubility of some of the biaryl
products in the former solvent, more extracting times (5–8×
3 mL) were required.
Acknowledgements
[7] P. G. Steel, W. T. Teasdale, Tetrahedron Lett. 2004, 45,
8977–8980.
This research was supported by the University of the Basque
Country (Project UPV 41.310–13656) and the Spanish Minis-
try of Education and Science (MEC CTQ2004–03706/BQU).
B. I. also thanks the University of the Basque Country for a
predoctoral scholarship. Petronor S.A. (Muskiz, Bizkaia) is
gratefully acknowledged for the generous donation of
hexane.
[8] a) T. H. Fife, R. Bembi, J. Am. Chem. Soc. 1993, 115,
11358–11363; b) T. J. Deming, J. Am. Chem. Soc. 1997,
119, 2759–2760.
[9] a) Z. Wang, X. Han, Z. Zhai, Chemosphere 2005, 62,
349–356; b) X. Liu, Z. Yang, L. Wang, Water Environ.
Res. 2005, 77, 519–524; c) E. S. F. Ma, W. D. Bates, A.
Edmunds, L. R. Kelland, T. Fojo, N. Farrell, J. Med.
Chem. 2005, 48, 5651–5654.
[10] R-A. Fallahpour, Synthesis 2000, 1138–1142.
[11] Boronic Acids: Preparation and Applications in Organ-
ic Synthesis and Medicine, (Ed.: D. G. Hall), VCH,
Weinheim, 2005.
[12] For a recent review on Suzuki–Miyaura reaction, see:
a) A. Suzuki, Chem. Commun. 2005, 4759–4763; see
also: b) R. Franzén, Y. Xu, Can. J. Chem. 2005, 83,
266–272.
References
[1] See, for example: a) T. Nishimura, S. Uemura, Synlett
2004, 201–216; b) J. K. Edwards, B. E. Solsona, P.
Landon, A. F. Carley, A. Herzing, C. J. Kiely, G. J.
Hutchings, J. Catal. 2005, 236, 69–79; c) D. Astruc, K.
Heuze, S. Gatard, D. Mery, S. Nlate, L. Plault, Adv.
Adv. Synth. Catal. 2006, 348, 1836 – 1840
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1839