X. Ding et al. / Tetrahedron Letters 51 (2010) 6105–6107
6107
5. Bøgevig, A.; Juhl, K.; Kumaragurubaran, N.; Zhuang, W.; Jørgensen, K. A. Angew.
Chem., Int. Ed. 2002, 41, 1790–1793.
6. Kumaragurubaran, N.; Juhl, K.; Zhuang, W.; Bøgevig, A.; Jørgensen, K. A. J. Am.
Chem. Soc. 2002, 124, 6254–6255.
aldehyde intermediate), whereas the ionic liquid residue contain-
ing 1 was dried under vacuum for about 60 min at 60 °C, and re-
used for the next run of reaction. This procedure could be
repeated for four times and the product could be obtained without
significant decrease in enantioselectivities and yields (Table 3).18
In summary, we successfully applied the imidazolium ion-
7. (a) Vogt, H.; Vanderheiden, S.; Bräse, S. Chem. Commun. 2003, 2448–2449; (b)
Baumann, T.; Vogt, H.; Bräse, S. Eur. J. Org. Chem. 2007, 266–282; (c) Baumann,
T.; Bächle, M.; Hartmann, C.; Bräse, S. Eur. J. Org. Chem. 2008, 2207–2212.
8. Suri, J. T.; Steiner, D. D.; Barbas, C. F., III Org. Lett. 2005, 7, 3885–3888.
9. Chowdari, N. S.; Ramachary, D. B.; Barbas, C. F., III Org. Lett. 2003, 5, 1685–1688.
10. (a) Dahlin, N.; Bøgevig, A.; Adolfsson, H. Adv. Synth. Catal. 2004, 346, 1101–
1105; (b) Chowdari, N. S.; Barbas, C. F., III Org. Lett. 2005, 7, 867–870; (c)
Franzén, J.; Marigo, M.; Fielenbach, S.; Wabnitz, T. C.; Kjærsgaard, A.; Jørgensen,
K. A. J. Am. Chem. Soc. 2005, 127, 18296–18304; (d) Thomassigny, C.; Prim, D.;
Greck, C. Tetrahedron Lett. 2006, 47, 1117–1119; (e) Liu, T. Y.; Cui, H. L.; Zhang,
Y.; Jiang, K.; Du, W.; He, Z. Q.; Chen, Y. C. Org. Lett. 2007, 9, 3671–3674; (f)
Hayashi, Y.; Aratake, S.; Imai, Y.; Hibino, K.; Chen, Q. Y.; Yamaguchi, J.;
Uchimaru, T. Chem. Asian J. 2008, 3, 225–232; (g) Liu, P. M.; Chang, C.; Reddy, R.
J.; Ting, Y. F.; Kuan, H. H.; Chen, K. Eur. J. Org. Chem. 2010, 42–46.
tagged proline 1 to catalyze the direct asymmetric
of unmodified aldehydes with azodicarboxylates. In ionic liquids
as reaction solvents, the desired -aminated alcohols were ob-
a-amination
a
tained with high chemical yields and excellent enantioselectivities
in a short period of reaction time. Furthermore, it is remarkable
that the catalyst 1/[bmim] [BF4] system could be easily recycled
and retained similar reactivity as well as enantioselectivity after
four recycles.
11. Kotrusz, P.; Alemayehu, S.; Toma, S.; Schmalz, H. G.; Adler, A. Eur. J. Org. Chem.
2005, 4904–4911.
Acknowledgments
12. (a) Baudequin, C.; Baudoux, J.; Levillain, J.; Cahard, D. A.; Gaumont, C.;
Plaquevent, J. C. Tetrahedron: Asymmetry 2003, 14, 3081–3093; (b) Ding, J.;
Armstrong, D. W. Chirality 2005, 17, 281–292; (c) Baudequin, C.; Bregeon, D.;
Levillain, J.; Guillen, F.; Plaquevent, J. C. Tetrahedron: Asymmetry 2005, 16,
3921–3945; (d) Bica, K.; Gaertner, P. Eur. J. Org. Chem. 2008, 19, 3235–3250; (e)
Winkel, A.; Reddy, P. V. G.; Wilhelm, R. Synthesis 2008, 999–1016; (f)
Domínguez de María, P. Angew. Chem., Int. Ed. 2008, 47, 6960–6968.
13. (a) Davis, J. H. Chem. Lett. 2004, 33, 1072–1077; (b) Fei, Z.; Geldbach, T. J.; Zhao,
D.; Dyson, P. J. Chem. Eur. J. 2006, 12, 2122–2130; (c) Luo, S.; Mi, X.; Zhang, L.;
Liu, S.; Cheng, J. P. Angew. Chem., Int. Ed. 2006, 45, 3093–3097; (d) Miao, W.;
Chan, T. H. Adv. Synth. Catal. 2006, 348, 1711–1718; (e) Zhou, L.; Wang, L. Chem.
Lett. 2007, 36, 628–629; (f) Luo, S. Z.; Zhang, L.; Mi, X. L.; Qiao, Y. P.; Cheng, J. P.
J. Org. Chem. 2007, 72, 9350–9352; (g) Lombardo, M.; Pasi, F.; Easwar, S.;
Trombini, C. Adv. Synth. Catal. 2007, 349, 2061–2065; (h) Yacob, Z.; Shah, J.;
Leistner, J.; Liebscher, J. Synlett 2008, 2342–2344; (i)Ionic Liquids in Synthesis;
Wasserscheid, P., Welton, T., Eds.; Wiley-VCH: Weinheim, 2008; Vol. 2, pp
488–527; (j) Ni, B.; Zhang, Q. Y.; Dhungana, K.; Headley, A. D. Org. Lett. 2009,
11, 1037–1040; (k) Lombardo, M.; Easwar, S.; Pasi, F.; Trombini, C. Adv. Synth.
Catal. 2009, 351, 276–282.
We gratefully acknowledge the National Natural Science Foun-
dation of China (20832001, 20972065, 21074054) and the National
Basic Research Program of China (2007CB925103, 2010CB92330)
for their financial support. The Program for The Major Scientific
and Technological Special Project (2009ZX09103-081) is also
acknowledged.
Supplementary data
Supplementary data (1H NMR and HPLC reports of 4a–4g) asso-
ciated with this article can be found, in the online version, at
ˇ
14. Toma, Š.; Meciarova˘, M.; ebesta, R. Š. Eur. J. Org. Chem. 2009, 321–327.
References and notes
15. Ding, X.; Tang, W. M.; Cheng, Y. X.; Zhu, C. J. Adv. Synth. Catal. 2010, 352, 108.
16. (a) Kotrusz, P.; Kmentová, I.; Gotov, B.; Toma, S.; Solcániová, E. Chem. Commun.
2002, 2510–2511; (b) Loh, T. P.; Feng, L. C.; Yang, H. Y.; Yang, J. Y. Tetrahedron
Lett. 2002, 43, 8741–8743; (c) Dere, R. T.; Pal, R. R.; Patil, P. S.; Salunkhe, M. M.
Tetrahedron Lett. 2003, 44, 5351–5353.
17. General procedure for the direct asymmetric
test-tube equipped with a magnetic stirring bar and charged with ionic liquid
(1.5 mL) was added catalyst (10 mol %) and aldehyde (0.5 mmol). The
1. (a) Gennari, C.; Colombo, L.; Bertolini, G. J. Am. Chem. Soc. 1986, 108, 6394; (b)
Evans, D. A.; Britton, T. C.; Dorow, R. L.; Dellaria, J. F. J. Am. Chem. Soc. 1986, 108,
6395; (c) Trimble, L. A.; Vederas, J. C. J. Am. Chem. Soc. 1986, 108, 6397–6399;
(d) Evans, D. A.; Britton, T. C.; Ellman, J. A.; Dorow, R. L. J. Am. Chem. Soc. 1990,
112, 4011–4030; (e) Harding, J. R.; Hughes, R. A.; Kelly, N. M.; Sutherlan, A.;
Willis, C. L. J. Chem. Soc., Perkin Trans. 1 2000, 3406–3416; (f) Chao, C. S.; Cheng,
C. K.; Li, S. H.; Chen, K. Tetrahedron Lett. 2009, 50, 333–336.
2. (a) Mashiko, T.; Hara, K.; Tanaka, D.; Fujiwara, Y.; Kumagai, N.; Shibasaki, M. J.
Am. Chem. Soc. 2007, 129, 11342–11343; (b) Mashiko, T.; Kumagai, N.;
Shibasaki, M. Org. Lett. 2008, 10, 2725–2728; (c) Kang, Y. K.; Kim, D. Y.
Tetrahedron Lett. 2006, 47, 4565–4568; (d) Marigo, M.; Juhl, K.; Jørgensen, K. A.
Angew. Chem., Int. Ed. 2003, 42, 1367–1369; (e) Juhl, K.; Jørgensen, K. A. J. Am.
Chem. Soc. 2002, 124, 2420–2421; (f) Dessole, G.; Bernardi, L.; Bonini, B. F.;
Capito, E.; Fochi, M.; Herrera, R. P.; Ricci, A.; Cahiez, G. J. Org. Chem. 2004, 69,
8525–8528; (g) Evans, D. A.; Johnson, D. S. Org. Lett. 1999, 1, 595–598; (h) He,
R.; Wang, X.; Hashimoto, T.; Maruoka, K. Angew. Chem., Int. Ed. 2008, 47, 9466–
9468; (i) Liu, Y.; Melgar-Fernandez, R.; Juaristi, E. J. Org. Chem. 2007, 72, 1522–
1525; (j) Terada, M.; Nakano, M.; Ube, H. J. Am. Chem. Soc. 2006, 128, 16044–
16045; (k) Xu, X.; Yabuta, T.; Yuan, P.; Takemoto, Y. Synlett 2006, 137–140; (l)
Liu, X.; Li, H.; Deng, L. Org. Lett. 2005, 7, 167–169; (m) Saaby, S.; Bella, M.;
Jørgensen, K. A. J. Am. Chem. Soc. 2004, 126, 8120–8121; (n) Pihko, P. M.;
Pohjakallio, A. Synlett 2004, 2115–2118; (o) Gómez Aranda, V.; Barluenga, J.;
Aznar, F. Synthesis 1974, 504; (p) Li, G.; Wei, H. X.; Kim, S. H.; Carducci, M.
Angew. Chem., Int. Ed. 2001, 40, 4277–4280.
a-amination in [bmim] [BF4]: To a
1
mixture was stirred for 2 min at 0 °C followed by addition of azodicarboxylates
(0.25 mmol). The resulting solution was then stirred until the yellow color of
the mixture disappeared and the completion of amination reaction was
determined by TLC. The reaction mixture was then extracted with ethyl ether
(6 Â 5 mL) followed by solvent evaporation using a rotary evaporator. To the
crude
a-hydrazine aldehyde intermediate was added methanol (2 mL). The
mixture was cooled to 0 °C and sodium borohydride (0.55 mmol) was added.
After 5 min, the reaction was quenched with saturated aqueous ammonium
chloride solution (0.5 mL) and the resulting mixture was extracted with ethyl
acetate (4 Â 3 mL). The combined organic extracts were dried over anhydrous
sodium sulfate and concentrated under vacuum after filtration. Purification by
column chromatography on silica gel (ethyl acetate/petroleum ether, 1:3–
1:10) gave pure a-aminated products as white solids.
18. Procedure for the recycle and reuse of 1/[bmim] [BF4]. The mixture of catalyst 1,
propionic aldehyde 2a, and dibenzyl azodicarboxylate 3a (0.1:1:2) in [bmim]
BF4 (1.5 mL) were stirred for 20 min at 0 °C and then extracted with ethyl ether
(6 Â 5 mL). The residue was dried under vacuum for about 60 min at 60 °C, and
reused for the next run of reaction. This procedure could be repeated for four
times at least.
3. Duthaler, R. O. Angew. Chem., Int. Ed. 2003, 42, 975–978.
4. List, B. J. Am. Chem. Soc. 2002, 124, 5656–5657.