Yang & Xu
FULL PAPER
Table 3 Recovery and reuse of the polymeric chiral diene
ligand 6b in enantioselective 1,4-addition of 2-cyclopentenone
(7b)a
should provide useful information for future design and
development of other polymeric chiral ligands for
asymmetric catalysis.
O
O
Polymeric diene 6b (5 mol%)
[Rh(C2H4)2Cl]2 (2 mol% Rh)
Acknowledgement
+
PhB(OH)2
K3PO4, dioxane/H2O, 55 oC
*
Financial support from the National Natural Science
Foundation of China (Nos. 20632060, 20972172,
21021063), and the Chinese Academy of Sciences is
greatly acknowledged.
Ph
Entry
Time/h
8
Yieldb/%
eec/
1
2
3
4
98
91
85
39
83
81
78
63
10
12
References
16
[1] (a) Hayashi, T.; Ueyama, K.; Tokunaga, N.; Yoshida, H. J. Am.
Chem. Soc. 2003, 125, 11508; (b) Fischer, C.; Defieber, C.; Suzuki,
T.; Carreira, E. M. J. Am. Chem. Soc. 2004, 126, 1628.
[2] For reviews on chiral olefin ligands in asymmetric catalysis, see: (a)
Glorius, F. Angew. Chem., Int. Ed. 2004, 43, 3364; (b) Johnson, J. B.;
Rovis, T. Angew. Chem., Int. Ed. 2008, 47, 4482; (c) Defieber, C.;
Grützmacher, H.; Carreira, E. M. Angew. Chem., Int. Ed. 2008, 47,
4482; (d) Shintani, R.; Hayashi, T. Aldrichim. Acta 2009, 42, 31; (e)
Feng, C.-G.; Xu, M.-H.; Lin, G.-Q. Synlett 2011, 1345.
a The reaction was conducted on a 0.3 mmol scale, using 2 equiv.
of phenylboronic acid in 1 mL of dioxane and 100 μL of aq
K3PO4 (1.5 mol/L) at 55 ℃ following the general procedure,
b
[Rh(C2H4)2Cl]2 was added at every time of the reuse. Isolated
yield. c Determined by HPLC analysis on a chiral OB-H column
[detected at 214 nm; eluent∶n-hexane/iso-propanol=99/1 (V/V),
flow rate=1.0 mL/min].
[3] (a) Chiral Catalyst Immobilization and Recycling, Eds: de Vos, D.
E.; Vankelecom, I. F. J.; Jacobs, P. A., Wiley-VCH, Weinheim,
Germany, 2000; (b) Polymeric Materials in Organic Synthesis and
Catalysis, Eds: Buchmeiser, M. R., Wiley-VCH, Weinheim, Ger-
many, 2003; (c) Handbook of Asymmetric Heterogeneous Catalysis,
Eds: Ding, K.; Uozumi, Y., Wiley-VCH, Weinheim, Germany, 2008;
(d) Recoverable and Recyclable Catalysts, Eds: Benaglia, M., John
Wiley & Sons, Chichester, United Kingdom, 2009.
Scheme 2 Rh-catalyzed arylation using polymeric diene ligand
6b
Ts
Polymeric diene 6b (3.3 mol%)
[Rh(C2H4)2Cl]2 (3 mol% Rh)
N
H
4-methoxyphenylboronic acid
aq. KHF2 (3 mol/L), toluene, 55 oC, 18 h
[4] (a) Wang, Z.-Q.; Feng, C.-G.; Xu, M.-H.; Lin, G.-Q. J. Am. Chem.
Soc. 2007, 129, 5336; (b) Feng, C.-G.; Wang, Z.-Q.; Tian, P.; Xu,
M.-H.; Lin, G.-Q. Chem. Asian J. 2008, 3, 1511; (c) Wang, Z.-Q.;
Feng, C.-G.; Zhang, S.-S.; Xu, M.-H.; Lin, G.-Q. Angew. Chem., Int.
Ed. 2010, 49, 5780; (d) Wang, L.; Wang, Z.-Q.; Xu, M.-H.; Lin,
G.-Q. Synthesis 2010, 3263; (e) Yang, H.-Y.; Xu, M.-H. Chem.
Commun. 2010, 46, 9223.
Ts
HN
OMe
29% yield, 69% ee
[5] For a similar work from other group using bicyclic [3.3.0] diene as
ligand, see: Helbig, S.; Sauer, S.; Cramer, N.; Laschat, S.; Baro, A.;
Frey, W. Adv. Synth. Catal. 2007, 349, 2331.
[6] For selected recent work from Lin group using bicyclic [3.3.0] diene
as ligand, see: (a) Cui, Z.; Yu, H.-J.; Yang, R.-F.; Gao, W.-Y.; Feng,
C.-G.; Lin, G.-Q. J. Am. Chem. Soc. 2011, 133, 12394; (b) Yu, H.-J.;
Shao, C.; Cui, Z.; Feng, C.-G.; Lin, G.-Q. Chem. Eur. J. 2012, 18,
13274.
[7] Yang, H.-Y. Ph.D. Dissertation, Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, Shanghai, 2010 (in Chi-
nese).
[8] For a review see: (a) Pu, L. Chem. Rev. 1998, 98, 2405; For selected
examples, see: (b) Hu, Q.-S.; Huang, W.-S.; Vitharana, D.; Zheng,
X.-F.; Pu, L. J. Am. Chem. Soc. 1997, 119, 12454; (c) Yu, H.-B.; Hu,
Q.-S.; Pu, L. J. Am. Chem. Soc. 2000, 122, 6500; (d) Huang, W.-S.;
Hu, Q.-S.; Pu, L. J. Org. Chem. 1999, 64, 7940; (e) Yu, H.-B.; Hu,
Q.-S.; Pu, L. Tetrahedron Lett. 2000, 41, 1681.
Conclusions
For the first time the sterically regular A-B type
polymeric chiral diene ligands bearing a nonbridged
bicyclic [3.3.0] backbone were designed and synthe-
sized for transition-metal-catalyzed asymmetric reac-
tions. The resulting immobilized diene ligand 6b well
behaved in Rh-catalyzed 1,4-addition of arylboronic
acid to α,β-unsaturated carbonyl compounds under reac-
tion conditions, showing relatively good activity and
good to excellent enantioselectivity (up to 94% ee). The
immobilized chiral diene ligand can be easily recycled
and reused for three times without significant loss of
enantioselectivity, while the drop in reactivity can be
overcome by prolonging the reaction time. This work
(Lu, Y.)
122
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Chin. J. Chem. 2013, 31, 119—122