Table 3 Palladium-catalyzed Suzuki–Miyaura coupling of alkenyl
mesylatesa
examples of alkenyl mesylate coupling with organoboron
coupling partners. The versatility of this catalytic system can be
highlighted by the mild reaction conditions with functional group
tolerances, as well as the unique alkenyl tosylate/mesylate pattern
with respect to vinyl halides that may not be readily available.
We thank the Research Grants Council of Hong Kong
(GRF: PolyU5014/10P) for financial support. We are grateful
to Ms Pui Yee Yeung and Ms Pui Ying Choy (PolyU, Hong
Kong) for their assistance in preparing some alkenyl sulfo-
nates. Special thanks to Prof. Man-Kin Wong, Ms Karen
Ka-Yan Kung and Mr Yat-Shing Fung (PolyU, Hong Kong)
for partial support of ketone precursors.
%
Temperature Yieldb
Entry Alkenyl OTs ArB(OH)2 Product
1
50 1C
95
Notes and references
2
3
50 1C
50 1C
80
85
1 (a) A. de Meijere, in Metal-Catalyzed Cross-Coupling Reactions,
ed. F. Diederich, Wiley-VCH, Weinheim, 2nd edn, 2004, vol. 1–2;
(b) A. Zapf and M. Beller, Chem. Commun., 2005, 431;
(c) J.-P. Corbet and G. Mignani, Chem. Rev., 2006, 106, 2651;
(d) A. Roglans, A. Pla-Quintana and M. Moreno-Manas, Chem.
Rev., 2006, 106, 4622; (e) R. Martin and S. L. Buchwald, Acc.
Chem. Res., 2008, 41, 1461; (f) F. Y. Kwong and A. S. C. Chan,
Synlett, 2008, 1440.
2 (a) A. O. King and N. Yasuda, in Organometallics in Process
Chemistry, ed. R. D. Larsen, Springer-Verlag, Berlin, Heidelberg,
2004, pp. 205–245; (b) C. Torborg and M. Beller, Adv. Synth.
Catal., 2009, 351, 3027; (c) M. C. Kozlowski, B. J. Morgan and
E. C. Linton, Chem. Soc. Rev., 2009, 38, 3193; (d) K. C. Nicolaou,
P. G. Bulger and D. Sarlah, Angew. Chem., Int. Ed., 2005, 44, 4442.
3 For a recent review of alkenylation, see: R. Rossi, F. Bellina and
M. Lessi, Synthesis, 2010, 4131.
4 For selected pharmaceutical examples at GlaxoSmithKline, see:
V. I. Elitzin, K. A. Harvey, H. Kim, M. Salmons, M. J. Sharp,
E. A. Tabet and M. A. Toczko, Org. Process Res. Dev., 2010, 14, 912.
5 For selected pharmaceutical examples at Pfizer, see: (a) T. E. Jacks,
D. T. Belmont, C. A. Briggs, N. M. Horne, G. D. Kanter,
G. L. Karrick, J. J. Krikke, R. J. McCabe, J. G. Mustakis,
T. N. Nanninga, G. S. Risedorph, R. E. Seamans, R. Skeean,
D. D. Winkle and T. M. Zennie, Org. Process Res. Dev., 2004,
8, 201; (b) D. D. Winkle and K. M. Schaab, Org. Process Res. Dev.,
2001, 5, 450.
6 The suggested prices of the sulfonating agents are: Tf2O, approx.
USD$1.3 per gram; TsCl, approx. USD$0.042 per gram; MsCl,
approx. USD$0.050 per gram from commercial suppliers.
7 For activated substrates in nickel catalysis, see: (a) Z.-Y. Tang and
Q.-S. Hu, Adv. Synth. Catal., 2004, 346, 1635; (b) J.-i. Kuroda,
K. Inamoto, K. Hiroya and T. Doi, Eur. J. Org. Chem., 2009, 2251.
8 For activated substrates in palladium catalysis for C–C couplings,
see: (a) J. M. Baxter, D. Steinhuebel, M. Palucki and I. W. Davies,
Org. Lett., 2005, 7, 215; (b) S. B. Kang, E. D. Clercq and
M. K. Lakshman, J. Org. Chem., 2007, 72, 5273; (c) L. Zhang,
T. Meng, R. Fan and J. Wu, J. Org. Chem., 2007, 72, 7279;
(d) H. Nakatsuji, H. Nishikado, K. Ueno and Y. Tanabe, Org.
Lett., 2009, 11, 4258. During the completion of our manuscript, a
communication describing fluoro-vinyl tosylate couplings was
reported, see: (e) H. Zhang, C.-B. Zhou, Q.-Y. Chen, J.-C. Xiao
and R. Hong, Org. Lett., 2011, 13, 560.
4
5
110 1C
87
110 1C
87
80
6
50 1C
a
Reaction conditions: alkenyl-OMs (1.0 mmol), ArB(OH)2 (2.0 mmol),
Pd(OAc)2 (2 mol%), CM-phos (Pd/L, 1 : 4), K3PO4ÁH2O (3.0 mmol),
t-BuOH (3.0 mL) were stirred at 50 1C for 4 h or 110 1C for 2 h under
b
nitrogen. Isolated yields.
Other non-aromatic cumarin derivatives also furnished the
corresponding coupling products smoothly (entries 11–12).
To expand the substrate scope further, we next tested the
feasibility of using alkenyl mesylates as the coupling partners
(Table 3). To the best of our knowledge, there has been no
successful example using this substrate reported to date in
coupling reaction. The attempted study of this investigation
showed that the Pd/CM-phos system allowed the coupling of
vinyl mesylates with a series of arylboronic acids (entries 1–5).
The coupling conditions could be either at 50 1C for 2 hours or
110 1C for 4 hours. Sterically hindered or functionalized
arylboronic acids provided good yields of the desired products
(entries 4–5). The chloro group remained intact in these
reaction conditions (entry 6).
9 For the use of Buchwald-type biarylphosphine in handling non-
activated alkenyl substrates at 80–110 1C (2 examples each), see:
(a) B. Bhayana, B. P. Fors and S. L. Buchwald, Org. Lett., 2009,
11, 3954; (b) H. N. Nguyen, X. Huang and S. L. Buchwald, J. Am.
Chem. Soc., 2003, 125, 11818.
10 For the first successful amidation from enol tosylates, see:
(a) A. Klapars, K. R. Campos, C.-y. chen and R. P. Volante, Org.
Lett., 2005, 7, 1185; (b) J.-G. Lei and G.-Q. Lin, Chin. J. Chem., 2002,
20, 1263; (c) J.-G. Lei, M.-H. Xu and G.-Q. Lin, Synlett, 2004, 2364.
11 For our initial development of CM-phos, see: (a) C. M. So,
Z. Zhou, C. P. Lau and F. Y. Kwong, Angew. Chem., Int. Ed.,
2008, 47, 6402; (b) C. M. So, C. P. Lau and F. Y. Kwong, Angew.
Chem., Int. Ed., 2008, 47, 8059; (c) C. M. So, C. P. Lau,
A. S. C. Chan and F. Y. Kwong, J. Org. Chem., 2008, 73, 7731.
In summary, a simple catalytic system for alkenyl carbon–
carbon bond construction has been established. The palladium
system comprised of Pd(OAc)2/CM-phos is effective to tackle
an array of activated and non-activated alkenyl tosylates.
Particularly noteworthy is that we also achieved the first
c
8330 Chem. Commun., 2011, 47, 8328–8330
This journal is The Royal Society of Chemistry 2011