J.-H. Li et al. / Tetrahedron Letters 47 (2006) 9239–9243
9243
Uozumi, Y.; Nakai, Y. Org. Lett. 2002, 4, 2997; (d)
Yamada, Y. M. A.; Takeda, K.; Takahashi, H.; Ikegami,
S. Org. Lett. 2002, 4, 3371; (e) Mori, K.; Yamaguchi, K.;
Hara, T.; Mizugaki, T.; Ebitani, K.; Kaneda, K. J. Am.
Chem. Soc. 2002, 124, 11572; (f) Lan, P.; Berta, D.; Porco,
J. A., Jr.; South, M. S.; Parlow, J. J. J. Org. Chem. 2003,
68, 9678; (g) Datta, A.; Ebert, K.; Plenio, H. Organomet-
allics 2003, 22, 4685; (h) Wang, Y.; Sauer, D. R. Org. Lett.
2004, 6, 2793; (i) Okamoto, K.; Akiyama, R.; Kobayashi,
S. Org. Lett. 2004, 6, 1987; (j) Nishio, R.; Sugiura, M.;
Kobayashi, S. Org. Lett. 2005, 7, 4831.
Parry, P. R.; Tarbit, B. Tetrahedron 2005, 61, 5131; (i)
Kondolff, I.; Doucet, H.; Santelli, M. Synlett 2005, 2057;
(j) Kudo, N.; Perseghini, M.; Fu, G. C. Angew. Chem., Int.
Ed. 2006, 45, 1282; (k) Guram, A. S.; King, A. O.; Allen, J.
G.; Wang, X.; Schenkel, L. B.; Chan, J.; Bunel, E. E.;
Faul, M. M.; Larsen, R. D.; Martinelli, M. J.; Reider, P. J.
Org. Lett. 2006, 8, 1787.
8. For papers on the use of DABCO as the ligand for the
Pd(OAc)2-catalyzed Suzuki–Miyaura cross-coupling reac-
tion, see: (a) Li, J.-H.; Liu, W.-J. Org. Lett. 2004, 6, 2809;
(b) Li, J.-H.; Liu, W.-J.; Xie, Y.-X. J. Org. Chem. 2005, 70,
5409; (c) Li, J.-H.; Hu, X.-C.; Liang, Y.; Xie, Y.-X.
Tetrahedron 2006, 62, 31.
9. The loading level of Pd is 0.063 mmol/g, which was
determined by means of a inductively coupled plasma-
atomic emission spectrometer (ICP-AES). The loading
level of DABCO is about 1.720 mmol/g on the base of
nitrogen content by elemental analysis (Anal. Calcd for
C15nH22nN2nCln including 2% of C10mH12m: C, 81.02; H,
8.18; N, 4.76. Found: C, 81.58; H, 7.82; N, 4.48). We also
determined the loading level of DABCO (about
1.658 mmol/g) based on the chlorine content by titrimetric
analysis [primary standard: CNaCl = 0.02 M; titrant (stan-
4. For representative papers on polymer-supported N-het-
erocyclic carbene–palladium complexes, see: (a) Byun,
J.-W.; Lee, Y.-S. Tetrahedron Lett. 2004, 45, 1837; (b)
Kim, J.-H.; Jun, B.-H.; Byun, J.-W.; Lee, Y.-S. Tetra-
hedron Lett. 2004, 45, 5827; (c) Steel, P. G.; Teasdale, C.
W. T. Tetrahedron Lett. 2004, 45, 8977; (d) Kim, J.-H.;
Kim, J.-W.; Shokouhimehr, M.; Lee, Y.-S. J. Org. Chem
2005, 70, 6714; (e) Zheng, Y.; Stevens, P. D.; Gao, Y. J.
Org. Chem. 2006, 71, 537; (f) Kim, J.-W.; Kim, J.-H.; Lee,
D.-H.; Lee, Y.-S. Tetrahedron Lett. 2006, 47, 4745.
5. For representative papers on polymer-supported salen–
palladium complexes and others, see: (a) Phan, N. T. S.;
Brown, D. H.; Styring, P. Tetrahedron Lett. 2004, 45,
7915; (b) Phan, N. T. S.; Khan, J.; Styring, P. Tetrahedron
2005, 61, 12065.
dard solution): CAgNO ¼ 0:0204 M; indicator: K2CrO4;
3
titrate: the polymer-supported DABCO–palladium com-
plex 4 (129.2 mg), deionized water (25 mL) and K2CrO4
(0.25 mL)].
6. For representative papers on others polymer-supported
palladium complexes, see: (a) Lau, K. C. Y.; He, H. S.;
Chiu, P.; Toy, P. H. J. Comb. Chem. 2004, 6, 955; (b)
Weng, Z.; Teo, S.; Koh, L. L.; Hor, T. S. A. Organomet-
10. Typical experimental procedure for the palladium-catalyzed
Suzuki–Miyaura cross-coupling reaction. A mixture of aryl
halide 5 (0.5 mmol), arylboronic acid 6 (0.7 mmol), the
polymer-supported DABCO–palladium complex (4)
(0.25 mol %), K2CO3 (2.5 equiv) and H2O/CH3CH2OH
(1:1; 4 mL) was stirred at room temperature for desired
time until complete consumption of starting material as
monitored by TLC. The reaction mixture was filtered to
give a solution and a solid. The solution was evaporated,
then extracted by diethyl ether, evaporated in vacuum and
purified by flash column chromatography (hexane or
hexane/ethyl acetate) to give the target product. After
being washed by diethyl ether and dried, the solid was
subjected to a second run of the coupling by charging with
the same substrates, base and solvent (5, 6, K2CO3 and
H2O/CH3CH2OH).
´
allics 2004, 23, 3603; (c) Gil-Molto, J.; Karlstro¨m, S.;
´
Najera, C. Tetrahedron 2005, 61, 12168.
7. For selected recent papers on the palladium-catalyzed
Suzuki–Miyaura cross-couplings to construct heteroaryl-
aryls, see: (a) Molander, G. A.; Biolatto, B. J. Org. Chem.
2003, 68, 4302; (b) Barder, T. E.; Buchwald, S. L. Org.
Lett. 2004, 6, 2649; (c) Cioffi, C. L.; Spencer, W. T.;
Richards, J. J.; Herr, R. J. J. Org. Chem. 2004, 69, 2210;
(d) Occhiato, E. G.; Lo Galbo, F.; Guarna, A. J. Org.
Chem. 2005, 70, 7324; (e) Thompson, A. E.; Hughes, G.;
Batsanov, A. S.; Bryce, M. R.; Parry, P. R.; Tarbit, B. J.
Org. Chem. 2005, 70, 388; (f) Molander, G. A.; Felix, L. A.
J. Org. Chem. 2005, 70, 3950; (g) Dawood, K. M.;
Kirschning, A. Tetrahedron 2005, 61, 12121; (h) Thomp-
son, A. E.; Batsanov, A. S.; Bryce, M. R.; Saygili, N.;
11. The loading level of Pd was decreased to 0.039 mmol/g
after the fifth run, which was calculated by ICP-AES.