ORGANIC
LETTERS
2009
Vol. 11, No. 21
4890-4892
Nickel-Catalyzed Cross-Coupling
Reaction of Alkenyl Methyl Ethers with
Aryl Boronic Esters
Toshiaki Shimasaki,† Yuko Konno,‡ Mamoru Tobisu,*,† and Naoto Chatani*,‡
Frontier Research Base for Global Young Researchers, Graduate School of Engineering,
Osaka UniVersity, Suita, Osaka 565-0871, Japan, and Department of Applied Chemistry,
Faculty of Engineering, Osaka UniVersity, Suita, Osaka 565-0871, Japan
tobisu@chem.eng.osaka-u.ac.jp; chatani@chem.eng.osaka-u.ac.jp
Received August 26, 2009
ABSTRACT
The Ni(0)-catalyzed cross-coupling of alkenyl methyl ethers with boronic esters is described. Several types of alkenyl methyl ethers can be
coupled with a wide range of boronic esters to give the stilbene derivatives.
Transition metal-catalyzed cross-coupling reactions have
become some of the most important transformations in
organic synthesis.1 Among them, the Suzuki-Miyaura cross-
coupling reaction has been recognized as an excellent tool
for carbon-carbon bond formation,2 because boron reagents
are highly functional group tolerant, readily available, stable
to air and moisture, and nontoxic. Despite significant
advances, the electrophilic partner used in the Suzuki-Miyaura
reaction has primarily been limited to organohalides and
sulfonic esters.3 Recently, we reported that aryl methyl ethers
serve as electrophiles in Suzuki-Miyaura reactions4a via the
cleavage of unreactive C-OMe bonds under nickel cataly-
sis.5,6 Subsequently, Shi7a and Garg7b independently reported
Suzuki-Miyaura reactions of aryl carboxylates as an elec-
trophile. In our reaction, we observed that the fused aromatic
systems, such as methoxynaphthalenes, exhibited superior
reactivity to nonfused aromatic systems. We surmised that
the reactivity profile might be determined largely by the
aromaticity of the substrate. This hypothesis led us to apply
nonaromatic substrates, alkenyl methyl ethers, to our Ni-
catalyzed cross-coupling as the electrophilic coupling partner
(eq 1). Herein, we report our results along this line.
We initially examined the cross-coupling reaction of (Z)-
methyl styryl ether (Z-1a) with boronic ester 2a under
conditions similar to those reported for aryl methyl ethers.4a
As a result, the cross-coupling product 3a was obtained in
(3) Other minor electrophiles applicable to Suzuki-Miyaura reaction:
Diazonium salts: (a) Roglans, A.; Pla-Quintana, A.; Moreno-Man˜as, M.
Chem. ReV. 2006, 106, 4622. Phosphonium salts: (b) Hwang, L. K.; Na,
Y.; Lee, J.; Do, Y.; Chang, S. Angew. Chem., Int. Ed. 2005, 44, 6166.
Ammonium salts: (c) Blakey, S. B.; MacMillan, D. W. C. J. Am. Chem.
Soc. 2003, 125, 6046. Sulfonium salts: (d) Srogl, J.; Allred, G. D.;
Liebeskind, L. S. J. Am. Chem. Soc. 1997, 119, 12376. Azoles: (e) Liu, J.;
Robins, M. J. Org. Lett. 2004, 6, 3421. Aryltriazene/BF3: (f) Saeki, T.;
Son, E.-C.; Tamao, K. Org. Lett. 2004, 6, 617. Nitriles: (g) Yu, D.-G.;
Yu-M.; Guan, B.-T.; Li, B.-J.; Zheng, Y.; Wu, Z.-H.; Shi, Z.-J. Org. Lett.
2009, 11, 3374. Carboxylic anhydrides: (h) Gooꢀen, L. J.; Paetzold, J. AdV.
Synth. Catal. 2004, 346, 1665. Sulfonyl chlorides: (i) Dubbaka, S. R.; Vogel,
P. Org. Lett. 2004, 6, 95. Zhang, S.; Zeng, X.; Wei, Z.; Zhao, D.; Kang,
T.; Zhang, W.; Yan, M.; Luo, M. Synlett 2006, 1891.
† Frontier Research Base for Global Young Researchers, Graduate School
of Engineering.
‡ Department of Applied Chemistry, Faculty of Engineering.
(1) For general reviews of metal-catalyzed cross-coupling reactions, see:
(a) Metal-Catalyzed Cross-Coupling Reactions; de Meijere, A., Diederich,
F., Eds.; Wiley-VCH: New York, 2004. (b) Handbook of Organopalladium
Chemistry for Organic Synthesis; Negishi, E.-i., Ed.; Wiley-Interscience:
New York, 2002.
(2) (a) Miyaura, N. Top. Curr. Chem. 2002, 219, 11. (b) Suzuki, A.;
Brown, H. C. Organic Synthesis Via Boranes; Aldrich: Milwaukee, WI,
2003; Vol. 3. (c) Miyaura, N.; Suzuki, A. Chem. ReV. 1995, 95, 2457.
(4) (a) Tobisu, M.; Shimasaki, T.; Chatani, N. Angew. Chem., Int. Ed.
2008, 47, 4866. See also: (b) Kakiuchi, F.; Usui, M.; Ueno, S.; Chatani,
N.; Murai, S. J. Am. Chem. Soc. 2004, 126, 2706.
10.1021/ol901978e CCC: $40.75
Published on Web 10/07/2009
2009 American Chemical Society