4
Tetrahedron Letters
methylchlorobenzene (or 2,5-dimethylchlorobenzene) with 2-
(b) Miura, M. Angew. Chem. 2004, 116, 2251; Angew. Chem. Int.
Ed. 2004, 43, 2201;
c) Zapf, A.; Jackstell, R.; Rataboul, F.; Riermeier, T.; Monsees,
methylphenylboronic acid (or 2,6-dimethylphenylboronic acid)
gave the corresponding products in excellent yields within 44 h
(
A.; Fuhrmann, C.; Shaikh, N.; Dingerdissen, U. ; Beller, M. Chem.
Commun. 2004, 1, 38;
(entries 1−4). When 2,6-dimethylchlorobenzene was used as a
coupling partner, the coupling products were also obtained in
excellent yields with a 0.2 mol % catalyst loading (entries 5 and
(d) Liang, L. C.; Chien P. S.; Huang, M. H.; Organometallics
2005, 24, 353;
(
1
(
3
e) Kudo, N.; Persighini M.; Fu, G. C. Angew. Chem. 2006, 118,
304; Angew. Chem. Int. Ed. 2006, 45, 1282;
f) Schweizer, S.; Becht, J.; Drian, C. L.; Org. Lett. 2007, 19,
777;
6
).
A pathway for the activation of the catalyst is proposed
Scheme 2). First, the isopropoxide anion attack the Pd(II)
(
(
(
g) Han, J.; Liu Y.; Guo, R.; J. Am. Chem. Soc. 2009, 131, 2060;
h) Zeng, X.; Zhang, T.; Qin, Y.; Wei, Z.; Luo, M.; Dalton Trans.
complex to form a palladium coordinated isopropoxide which
would lead to formation of a Pd-hydride species with elimination
2
009, 39, 8341;
of a molecule of acetone. Next, elimination of HCl generate a
(i) Jin, M. J.; Lee, D. H.; Angew. Chem. Int. Ed. 2010, 49, 1119;
(j) Yang, W.; Liu, C.; Qiu, J. Chem. Commun. 2010, 46, 2659;
(k) Peng, H.; Chen, Y.; Mao, S.; Pi, Y.; Chen, Y.; Lian, Z.; Meng,
T.; Liu, S.; Yu, G.; Org. Biomol. Chem. 2014, 12, 6944;
0
(
NHC)-Pd species which can be considered as the actual active
2
0
species. It is analogous to previously report.
The generated
electron-rich palladium(0) species stabilized by the presence of a
phenanthroline analogue NHC ligand then enters the catalytic
cycle performing the oxidative addition of aryl halides. Further
steps are the same as the well known accepted mechanism of
(l) Guan, Z.; Li, B.; Hai, G.; Yang, X.; Li, T.; Tan, B. RSC Adv.
2
014, 4, 36437.
3.
(a) Littke, A. F.; Fu, G. C. Angew. Chem. 2002, 114, 4350;
Angew. Chem. Int. Ed. 2002, 41, 4176;
(b) Yin, L.; Liebscher, J. Chem. Rev. 2007, 107, 133;
21
Suzuki-Miyaura cross-coupling.
(
c) Sommer, W. J.; Weck, M. Coord. Chem. Rev. 2007, 251, 860.
4
.
(a) Shen, Q.; Shekhar, S.; Stambuli, J. P.; Hartwig, J. F. Angew.
Chem. 2005, 117, 1395; Angew. Chem. Int. Ed. 2005, 44, 1371;
(
b) Iwasawa, T.; Komano, T.; Tajima, A.; Tokunaga, M.; Obora,
Y.; Fujihara, T.; Tsuji, Y. Organometallics 2006, 25, 4665;
c) Snelders, D. J. M.; van Koten, G., Klein Gebbink, R. J. M. J.
Am. Chem. Soc. 2009, 131, 11407;
d) Karimi, B.; Elhamfar, D.; Clark, J. H.; Hunt, A. J. Chem. Eur.
J. 2010, 16, 8047;
e) Yuan, B. Z.; Pan, Y. Y.; Li, Y. W.; Yin, B. L.; Jiang, H. F.
Angew. Chem. Int. Ed. 2010, 49, 4054;
(
(
(
(
(
(
f) Karimi, B.; Akhavan, P. F. Inorg. Chem. 2011, 50, 6063.
g) Lee, D. H.; Jin, M. J. Org. Lett. 2011, 13, 252;
h) Garrido, R.; ꢀernꢁnꢂeꢃ-Montes, P. S.; ꢄorꢂiꢅꢅo, ꢆ.; ꢄꢇꢈeꢃ-
Sal, P.; ꢉꢇꢊeꢃ-Mardomingo, C.; ꢂe ꢋesꢌs, E. Appl. Organometal.
Chem. 2012, 26, 425;
(
(
i) Dunsford, J. J.; Cavell, K. J. Organometallics 2014, 33, 2902;
j) Garrido, R.; ꢀernꢁnꢂeꢃ-Montes, P. S.; ꢄorꢂiꢅꢅo, ꢆ.; ꢄꢇꢈeꢃ-
Sal, P.; ꢉꢇꢊeꢃ-Mardomingo, C.; ꢂe ꢋesꢌs, E. Organometallics
015, 34, 1855.
(a) Navarro, O.; Marion, N.; Mei, J.; Nolan, S. P. Chem. Eur. J.
006, 12, 5142;
b) Zeiler, A.; Rudolph, M.; Rominger, F.; Hashmi, A. S. K.
Chem. Eur. J. 2015, 21, 11065;
c) Farina, V. Adv. Synth. Catal. 2004, 346, 1553;
2
5
.
2
(
Scheme 2. Proposed activation of catalyst.
In summary, two novel N-heterocyclic carbene palladium
complexes have been synthesized. For both catalysts, the two N
atoms of the 1,10-phenanthroline analogue N-heterocyclic
carbene ligand simultaneously coordinate with the palladium
which stabilizes the structure of the complexes. Complexes 5 and
(
(d) Bedford, R. B.; Cazin, C. S. J.; Hazelwood (nÿeWelch), S. L.
Angew. Chem. Int. Ed. 2002, 41, 4120;
(
e) Stambuli, J. P.; Kuwano, R.; Hartwig, J. F. Angew. Chem. Int.
Ed. 2002, 41, 4746;
f) Catone, D.; Guidoni, A. G.; Paladini, A.; Piccirillo, S.;
(
6
have been shown to be highly efficient for Suzuki-Miyaura
Rondino, F.; Satta, M.; Scuderi, D.; Speranza, M. Angew. Chem.
Int. Ed. 2004, 43, 1871.
Miyaura, N.; Yanagi, T.; Suzuki, A. Synth. Commun. 1981, 11,
coupling reactions of various aryl chlorides with arylboronic
acids. The reactions can be carried out in aqueous media at room
temperature, with catalyst loadings as low as 0.1% and high
yields are obtained. These features make these two catalysts very
attractive for use in industrial processes.
6.
5
13.
(a) So, C. M.; Lau, C. P.; Kwong, F. Y. Org. Lett. 2007, 9, 2795;
b) Harkal, S.; Rataboul, F.; Zapf, A.; Fuhrmann, C.; Riermeier,
T.; Monsees, A.; Beller, M. Adv. Synth. Catal. 2004, 346, 1742;
c) Littke, A. F.; Dai, C.; Fu, G. C. J. Am. Chem. Soc. 2000, 122,
7
.
(
(
Acknowledgments
4020.
8
9
.
.
Arduengo, A. J.; Harlow, R. L.; Kline, M. J. J. Am. Chem. Soc.
1
991, 113, 361.
This work was supported by the National Natural Science
Foundation of China (grant No. 41372373, 21572155,
(a) Curran, D. P.; Solovyev, A.; Brahmi, M. M.; Fensterbank, L.;
Malacria, M.; Lacôte, E. Angew. Chem. Int. Ed. 2011, 50, 10294;
(b) Pan, X.; Curran, D. P. Org. Lett. 2014, 16, 2728.
(c) Lamm, V.; Pan, X.; Taniguchi, T.; Curran, D. P. Beilstein J.
Org. Chem. 2013, 9, 675.
21372175), the Natural Science Foundation of Tianjin
(16JCYBJC19700), and the innovation team plan of the Tianjin
Education Committee (TD12-5037).
1
1
0. Díez-González, S.; Nolan, S. P. Coord. Chem. Rev. 2007, 251,
74.
1. (a) Huang, J.; Nolan, S. P. J. Am. Chem. Soc. 1999, 121, 9889;
b) Viciu, M. S.; Germaneau, R. F.; Navarro-Fernandez, O.;
8
References and notes
(
1
2
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.
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