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References
6, 169.
1. For a review, see: Kobayashi, S.; Ishitani, H. Chem. Rev.
1999, 99, 1069.
2. (a) Anderson, J. C.; Peace, S. Synlett 2000, 850; (b)
Adams, H.; Anderson, J. C.; Peace, S.; Pennell, A. M. K.
J. Org. Chem. 1998, 63, 9932.
3. For Mannich type reactions using silyl enol ether, see: (a)
Kobayashi, S.; Hamada, T.; Manabe, K. J. Am. Chem.
Soc. 2002, 124, 5640; (b) Nakamura, Y.; Matsubara, R.;
Kiyohara, H.; Kobayashi, S. Org. Lett. 2003, 5, 2481; (c)
Kobayashi, S.; Kiyohara, H.; Nakamura, Y.; Matsubara,
R. J. Am. Chem. Soc. 2004, 126, 6558.
4. (a) Nishiwaki, N.; Kundsen, K. R.; Gothelf, K.; Jørgen-
sen, K. A. Angew. Chem., Int. Ed. 2001, 40, 2992; (b)
Marigo, M.; Kjærsgaard, A.; Juhl, K.; Gathergood, N.;
Jørgensen, K. A. Chem. Eur. J. 2003, 9, 2359.
5. (a) For a review, see: Bolm, C.; Gerlach, A. Eur. J. Org.
Chem., 1998, 21; (b) Chiral Catalyst Immobilization and
Recycling; DeVos, D. E., Vankelecom, I. F. J., Jacobs, P.
A., Eds.; Wiley–VCH: Weinheim, 2000.
6. (a) Kresge, C. T.; Leonowicz, M. E.; Roth, W. J.; Vartuli,
J. C.; Beck, J. S. Nature 1992, 359, 710; (b) Zhao, D.;
Feng, J.; Huo, Q.; Melosh, N.; Fredrickson, G. H.;
Chmelka, B. F.; Stucky, G. D. Science 1998, 279, 548; (c)
Ying, J. Y.; Mehnert, C. P.; Wong, M. S. Angew. Chem.,
Int. Ed. 1999, 38, 57.
23
D
10. Compound 2: ½a ¼ þ63:5 (c 1.0, C2H5OH), 1H NMR
(300MHz, CDCl3): d 0.00 (s, 12H), 0.85 (s, 18H), 1.21–
1.24 (m, 16H), 1.46 (m, 4H), 2.06 (m, 4H), 3.55 (t,
J = 6.6Hz, 2H), 4.07 (q, J = 3.9Hz, 2H), 4.07 (dd, J = 7.17
and 4.28Hz), 4.61 (dd, J = 8.02 and 1.98Hz, 2H), 5.20
(dd, J = 8.02 and 1.98Hz, 2H), 7.24 (m, 10H). 13C NMR
(75MHz, CDCl3): d À4.86 (4C), 14.52, 18.79, 23.05,
23.05, 24.43, 24.43, 26.11, 26.11, 26.39 (6C), 30.03, 31.98,
32.96, 33.21, 63.67, 63.67, 69.99, 69.99, 74.42, 74.42,
126.27, 126.27, 127.14, 127.14, 127.14, 127.93,
127.93, 127.93, 129.06, 129.06, 142.77, 142.77, 169.50,
169.50.
23
D
11. Compound 3: ½a ¼ þ87:5 (c 1.0, C2H5OH), 1H NMR
(300MHz, CDCl3): d 1.36 (m, 8H), 1.53 (m, 4H), 1.72 (m,
2H), 2.08 (m, 6H), 3.42 (s, 2H), 3.57 (t, J = 6.50Hz, 4H),
4.13 (t, J = 8.18Hz, 2H), 4.66 (dd, J = 8.45 and 1.66Hz,
2H), 5.25 (dd, J = 7.96 and 2.1Hz, 2H), 7.32 (m, 10H). 13
C
NMR (75MHz, CDCl3) 20.59, 20.59, 24.17, 24.17, 25.66,
25.82, 29.81, 29.81, 32.76, 32.98, 46.52, 63.08, 63.08, 69.88,
69.88, 75.47, 75.47, 127.14 (4C), 128.00 (2C), 129.09 (4C),
142.63 (2C), 169.54 (2C).
12. The ligand loading in compound 4 was determined to be
0.51mmol/g by elemental analysis (average values C:
19.981%, H: 2.501%, N: 1.437%).
13. A representative procedure for the nitro-Mannich reaction
and repetition experiments: In a flame-dried Schlenk tube,
Cu(OTf)2 (18.7mg, 0.052mmol) and BOX ligand-grafted
silica 4 (92mg, 0.047mmol) were dried under reduced
pressure for 30min. To the mixture was added dry CH2Cl2
(4mL) and the solution stirred at rt for 3h to form the
ligand–metal complex. The mixture was filtered and
washed with CH2Cl2 (4mL · 2) to remove any free
Cu(OTf)2. To the mixture was added CH2Cl2 (4mL),
ethyl (4-methoxyphenylimino)acetate (48.6mg, 0.235
mmol), nitropropane (32lL, 0.35mmol), and triethylam-
ine (6.5lL, 0.047mmol) via syringe. The resultant solution
was stirred at rt for 3days. The solution was then filtered
and washed with CH2Cl2 (4mL · 2). Solvent from the
filtrate was removed under reduced pressure and the
residue purified on silica gel using CH2Cl2/n-pentane (1:1)
as eluent to give the desired product. Recovered catalyst
was washed with dry CH2Cl2 (4mL · 2) and used for
recycling experiments after drying under reduced pressure.
After the third experiment of recycling, additional
Cu(OTf)2 (18.7mg, 0.052mmol) was added and the
washing repeated. The diastereo and enantioselectivities
were determined through HPLC analysis using Chiralcel
ODꢂ (hexane/i-PrOH = 97:3, 0.5mL).
7. For reports from this laboratory, see: (a) Bae, S. J.; Kim,
S.-W.; Hyeon, T.; Kim, B. M. Chem. Commun. 2000, 31;
(b) Kim, S.-W.; Bae, S. J.; Hyeon, T.; Kim, B. M.
Micropor. Mesopor. Mater. 2001, 44–45, 523; (c) Park, J.
K.; Kim, S.-W.; Hyeon, T.; Kim, B. M. Tetrahedron:
Asymmetry 2001, 12, 2931; (d) Lee, H. M.; Kim, S.-W.;
Hyeon, T.; Kim, B. M. Tetrahedron: Asymmetry 2001, 12,
1537.
8. For a general review on reactions using mesoporous
catalysts, see: Ref. 6c and He, X.; Antonelli, D. Angew.
Chem., Int. Ed. Engl. 2002, 41, 214.
9. For representative examples of asymmetric reactions on
mesoporous silica, see: (a) Johnson, B. F. G.; Raynor, S.
A.; Shephard, D. S.; Mashmeyer, T.; Thomas, J. M.;
Sankar, G.; Bromley, S.; Oldroyd, R.; Gladden, L.;
Mantle, M. D. Chem. Commun. 1999, 1167; (b) Kim,
G. J.; Shin, J.-H. Tetrahedron Lett. 1999, 40, 6827; (c)
Zhou, X.-G.; Yu, X.-Q.; Huang, J.-S.; Li, S.-G.; Li, L.-S.;
Che, C.-M. Chem. Commun. 1999, 1789; (d) Piaggio, P.;
McMorn, P.; Langham, C.; Bethell, D.; Bulman-Page, P.
C.; Hancock, F. E.; Hutchings, G. J. New J. Chem. 1998,
1167; (e) Bellocq, N.; Abrmason, M.; Lasperas, M.;
Brunel, D.; Moreau, P. Tetrahedron: Asymmetry 1999,
10, 3229; (f) Rechavi, D.; Lemaire, M. Org. Lett. 2001, 3,