M. Berthod et al. / Tetrahedron: Asymmetry 15 (2004) 2219–2221
2221
Table 2. Recycling in ionic liquid
References and notes
Entry
Reuse Catalyst
Ionic
liquid
Conversion
(%)a
Ee
(%)b
1. (a) Wasserscheid, P.; Welton, T. Ionic Liquids in Synthesis;
Wiley-VCH: Weinheim, 2003; (b) Wasserscheid, P.; Keim,
W. Angew. Chem., Int. Ed. 2000, 39, 3772–3789; (c) Carlin,
R. T.; Wilkes, J. S. In Advances in Nonaqueous Chemistry;
Mamantov, G., Popov, A., Eds.; VCH: New York, 1994;
(d) Chauvin, Y.; Olivier-Bourbigou, H. CHEMTECH
1995, 25, 26; (e) Seddon, K. R. J. Chem. Technol.
Biotechnol. 1997, 68, 351; (f) Olivier-Bourbigou, H. In
Aqueous-Phase Organometallic Catalysis: Concept and
Applications; Cornils, B., Hermann, W. A., Eds.; Wiley-
VCH: Wienheim, 1998; (g) Zhao, D.; Wu, M.; Kou, Y.;
Min, E. Catal. Today 2002, 74, 157–189.
2. (a) Welton, T. Chem. Rev. 1999, 99, 2071; (b) Dupont, J.;
De Souza, R. F.; Suarez, P. A. Z. Chem. Rev. 2002, 102,
3667–3692; (c) Olivier-Bourbigou, H.; Magna, L. J. Mol.
Catal. A 2002, 182–183, 419–437.
3. (a) Lee, S.-G.; Zhang, Y. J.; Piao, J. Y.; Yoon, H.; Song,
C. E.; Choi, J. H.; Hong, J. Chem. Commun. 2003, 2624–
2625; (b) Berger, A.; De Souza, R. F.; Delgado, M. R.;
Dupont, J. Tetrahedron: Asymmetry 2001, 12, 1825–1828;
(c) Dyson, P. J.; Ellis, D. G.; Parker, D. G.; Welton, T.
Chem. Commun. 1999, 25.
1
2
3
4
9
3
3
4
4
100
100
100
100
76
90
85
90
1st
1st
9
9
9
a Conversion was determined by GC/MS.
b Ee was determined by HPLC with a CHIRALCELâ OD column.
tive after recycling but no explanation could be put
forward for this observation. Finally we were surprised
to observe a large decrease in selectivity when small
amounts of water (10%) were added in the ionic liquid
layer. We have no explanation for this but this effect has
already been observed at high hydrogen pressure in the
hydrogenation of tiglic acid in 4.4
We have demonstrated that minor modification of 4,40-
and 5,50-diamBINAP provides a polar and ionic liquid-
soluble BINAP analogue suitable for asymmetric
biphasic catalytic hydrogenation of ethyl acetoacetate in
RTILs. The use of such a media is not just interesting
for this substrate, which was hydrogenated in water/
organic solvent biphasic mixture with perfect conversion
and excellent ee. This paper shows the use of certain
BINAP derivatives is possible with more atypical media.
This could be extremely interesting for substrates or
catalysts, which need specific conditions.
4. Baudequin, C.; Baudoux, J.; Levillain, J.; Cahard, D.;
Gaumont, A. C.; Plaquevent, J. C. Tetrahedron: Asym-
metry 2003, 14, 3081–3093.
5. (a) Brown, R. A.; Pollet, P.; McKoon, E.; Eckert, C. A.;
Liotta, C. L.; Jessop, P. G. J. Am. Chem. Soc. 2001, 123,
1254–1255; (b) Monteiro, A. L.; Zinn, F. K.; DeSouza,
R. F.; Dupont, J. Tetrahedron: Asymmetry 1997, 8, 177–
179.
6. Ngo, H. L.; Hu, A.; Lin, W. Chem. Commun. 2003, 1912–
1913.
3. Experimental
7. Berthod, M.; Saluzzo, C.; Mignani, G.; Lemaire, M.
Tetrahedron: Asymmetry 2004, 15, 639–645.
8. (a) Lamouille, T.; Saluzzo, C.; ter Halle, R.; Le Guyader,
F.; Lemaire, M. Tetrahedron Lett. 2001, 42, 663–664; (b)
Under Ar, to the catalyst 9 or 10 (0.024 mmol) dissolved
in ionic liquid (1 mL), the ethyl acetoacetate (2.2 mL)
was added (substrate/catalyst ¼ 1000). This biphasic
mixture was allowed to stir and stand overnight in a
stainless steel hydrogenation vessel at 50 °C under
40 bars H2. The resulting homogeneous mixture was
extracted twice with pentane (10 mL). The ionic liquid
phase containing the catalyst was reused as previously
described.
^
Genet, J. P.; Pinel, C.; Ratovelomanana-Vidal, V.; Mall-
art, S.; Pfister, X.; Cano de Andrade, M.; Laffitte, J. A.
Tetrahedron: Asymmetry 1994, 5, 665–674.
9. Huddleston, J. G.; Visser, A. E.; Reichert, W. M.;
Willauer, H. D.; Broker, G. A.; Rogers, R. D. Green
Chem. 2001, 156.
10. Dyson, P. J.; Ellis, D. J.; Henderson, W.; Laurenczy, G.
Adv. Synth. Catal. 2003, 345, 216–221.