S. Luo et al. / Tetrahedron 63 (2007) 1923–1930
1929
1
CHCl ); H NMR (300 MHz, CDCl ): d 1.27–1.28 (1H, m),
3
99, 2071–2083; (c) Sheldon, R. Chem. Commun. 2001, 2399–
2407; (d) Dupont, J.; de Souza, R. F.; Suarez, P. A. Z. Chem.
Rev. 2002, 102, 3667–3692; (e) Wikes, J. S. J. Mol. Catal. A:
Chem. 2004, 214, 11–17; (f) Welton, T. Coord. Chem. Rev.
2004, 248, 2459–2477; (g) Song, C. E. Chem. Commun.
2004, 1033–1043; (h) Jain, N.; Kumar, A.; Chauhan, S.;
Chauhan, S. M. S. Tetrahedron 2005, 61, 1015–1060; (i) Lee,
S. G. Chem. Commun. 2006, 1049–1063; (j) Baudequin, C.;
Br ꢀe geon, D.; Levillain, J.; Guillen, F.; Plaquevent, J.-C.;
Gaumont, A.-C. Tetrahedron: Asymmetry 2005, 16, 3921–
3945.
3
1
3
(
.48 (9H, s), 1.60–1.75 (2H, br), 1.89–1.94 (1H, m), 3.14–
.37 (2H, m), 3.99–4.08 (2H, m), 4.22–4.26 (1H, m), 6.87
1H, s), 7.04 (1H, s), 7.44 (1H, s); C NMR (CDCl3,
5 MHz): d 23.3, 28.5, 29.1, 47.0, 48.6, 57.2, 79.8, 119.9,
29.4, 137.7, 162.3.
1
3
7
1
Under Ar, tosylation product of (S)-Boc-prolinol obtained
from the former step (1.38 g, 5.50 mmol) and n-butylbro-
mide (1.51 g, 11.0 mmol) were mixed in toluene (15 mL).
The solution was kept at 70 C and stirred for 24 h. The sol-
vent was then removed under vacuo and the residue was pu-
rified by flash chromatograph on silica gel to afford a pale
ꢁ
2. For recent examples, see: (a) Cole, A.; Jensen, J.; Ntai, I.; Loan,
K.; Tran, T.; Weaver, K.; Forbes, D.; Davis, J. J. Am. Chem.
Soc. 2002, 124, 5962–5963; (b) Gu, Y.; Shi, F.; Deng, Y.
Catal. Commun. 2003, 4, 597–601; (c) Forbes, D. C.;
Weaver, K. J. J. Mol. Catal. A: Chem. 2004, 214, 129–132;
(d) Gu, Y.; Shi, F.; Deng, Y. J. Mol. Catal. A: Chem. 2004,
212, 71–75; (e) Gui, J.; Ban, H.; Cong, X.; Zhang, X.; Hu,
Z.; Sun, Z. J. Mol. Catal. A: Chem. 2005, 225, 27–31; (f)
Gui, J.; Deng, Y.; Hu, Z.; Sun, Z. Tetrahedron Lett. 2004, 45,
2681–2683; (g) Li, D.; Shi, F.; Peng, J.; Guo, S.; Deng, Y. J.
Org. Chem. 2004, 69, 3582–3585; (h) Kitaoka, S.; Nobuoka,
K.; Ishikawa, Y. Chem. Commun. 2004, 1902–1903; (i) Fei,
Z.; Zhao, D.; Geldbach, T. J.; Scopelliti, R.; Dyson, P. J.
Chem.—Eur. J. 2004, 10, 4886–4893; (j) Zhao, G.; Jiang, T.;
Gao, H.; Han, B.; Huang, J.; Sun, D. Green Chem. 2004, 6,
75–77.
2
5
yellow viscous liquid (1.98 g, 93% yield). [a] ꢀ10.6 (c
D
1
1
.0, CHCl ); H NMR (300 MHz, CDCl ): d 0.98 (3H, t
3
3
J¼7.38, 7.32 Hz), 1.42 (11H, m), 1.79–2.15 (6H, m),
3
4
.23–3.52 (2H, m), 4.12–4.24 (1H, m), 4.25–4.41 (2H, m),
.48–4.72 (2H, m), 7.38 (1H, s), 7.41 (1H, s), 10.53 (1H,
1
3
s); C NMR (CDCl , 75 MHz): d 13.4, 19.4, 23.6, 28.3,
3
8.5, 32.1, 47.0, 49.9, 51.9, 57.1, 80.1, 121.5, 122.7,
37.7, 155.1; LC–MS: 308.15 (M ), 78.99, 81.02 (Br ).
2
1
+
ꢀ
To a solution of Boc-protected pyrrolidinyl-imidazolium
bromide (1.01 g, 2.70 mmol) in acetonitrile and acetone
50 mL, 9:1), was added well-sieved NaBF4 (1.32 g,
2.02 mmol). The mixture was vigorously stirred at room
temperature for three days. Filtered to remove the inorganic
(
1
salts and the filtrate was triturated with AgBF solution (in
4
3. For a review, see: (a) MacFarlane, D. R.; Pringle, J. M.;
Johansson, K. M.; Forsyth, S. A.; Forsyth, M. Chem.
Commun. 2006, 1905–1917; For recent examples, see: basic
catalysts: (b) Ranu, B. C.; Banerjee, S. Org. Lett. 2005, 7,
3049–3052; (c) Zhu, A.; Jiang, T.; Wang, D.; Han, B.; Liu,
L.; Huang, J.; Zhang, J.; Sun, D. Green Chem. 2005, 7, 514–
517; (d) Jiang, T.; Gao, H.; Han, B.; Zhao, G.; Chang, Y.;
Wu, W.; Gao, L.; Yang, G. Tetrahedron Lett. 2004, 45, 2699–
2701; (e) Xu, J.-M.; Liu, B.-K.; Wu, W.-B.; Qian, C.; Wu,
Q.; Lin, X.-F. J. Org. Chem. 2006, 71, 3991–3993; (f) Ranu,
B. C.; Jana, R. Eur. J. Org. Chem. 2006, 3767–3770;
Nucleophilic catalysts: (g) Kim, D. W.; Song, C. E.; Chi,
D. Y. J. Am. Chem. Soc. 2002, 124, 10278–10279; (h) Kim,
D. W.; Song, C. E.; Chi, D. Y. J. Org. Chem. 2003, 68, 4281–
4285; (i) Kim, D. W.; Choe, Y. S.; Chi, D. Y. Nucl. Med.
Biol. 2003, 30, 345–350; (j) Kim, D. W.; Chi, D. Y. Angew.
Chem., Int. Ed. 2004, 483–485; (k) Xu, L.-W.; Gao, Y.; Yin,
J.-J.; Li, L.; Xia, C.-G. Tetrahedron Lett. 2005, 46, 5317–
5320; (l) Ranu, B. C.; Dey, S. S. Tetrahedron 2004, 60,
4183–4188; (m) Xu, L.-W.; Li, J.-W.; Zhou, S.-L.; Xia, C.-G.
New J. Chem. 2004, 28, 183–184; (n) Mi, X. L.; Luo, S. Z.;
Cheng, J.-P. J. Org. Chem. 2005, 70, 2338–2341.
acetonitrile) till no precipitation was formed. Filtered again
and concentrated. The residue was diluted with CH Cl and
2
2
the insoluble part was removed by filtration. The clear fil-
trate was concentrated under vacuo and the residue was
treated in 4 M HCl dioxane solution. The solution was con-
centrated under vacuo to give the hydrogen chloride salts,
which was subsequently neutralized in saturated NaHCO3
solution (70 mL). The aqueous solution was evaporated to
dryness under vacuo and the solid residue was extracted
with chloroform (20 mLꢂ6). The combined organic layer
was concentrated in vacuo to afford a pale yellow and clear
2
5
liquid 1b (0.8 g, 100% yield). [a] +25.5 (c 1.0, CHCl ); IR
3
D
ꢀ1
1
(
KBr, cm ): 3428, 2961, 1562, 1401, 1083; H NMR
(
300 MHz, CDCl ): d 0.88 (3H, t, J¼7.5 Hz), 1.26–1.33
3
(
(
(
3H, m), 1.63–1.65 (2H, m), 1.77–1.82 (2H, m), 1.90–1.93
1H, m), 2.78–2.86 (2H, m), 3.49–3.52 (1H, m), 3.89–3.97
1H, m), 4.12–4.22 (3H, m), 7.27 (1H, s), 7.47 (1H, s),
1
3
8
2
1
2
.97 (1H, s); C NMR (CDCl , 75 MHz): d 13.3, 19.4,
3
5.9, 29.0, 31.9, 46.5, 49.7, 54.3, 57.4, 121.5, 123.3,
36.1. HRMS for C H N (M ) calcd 208.1808, found
08.1806.
+
2 22 3
+
1
4
. (a) Luo, S. Z.; Mi, X. L.; Zhang, L.; Liu, S.; Xu, H.; Cheng, J.-P.
Angew. Chem., Int. Ed. 2006, 45, 3093–3097; (b) Luo, S. Z.;
Mi, X. L.; Liu, S.; Xu, H.; Cheng, J.-P. Chem. Commun.
Acknowledgements
2
006, 3687–3689.
This work was supported by the Natural Science Foundation
of China (NSFC 20452001, 20421202, and 20542007), the
Ministry of Science and Technology (MoST), and the Insti-
tute of Chemistry, Chinese Academy of Sciences (ICCAS).
5. Heathcock, C. H. Comprehensive Organic Synthesis; Trost,
B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 2.
6. For reviews, see: (a) Alcaide, B.; Almendros, P. Eur. J. Org.
Chem. 2002, 1595–1601; (b) Shibasaki, M.; Yashikawa, N.
Chem. Rev. 2002, 102, 2187–2210.
7
. List, B. Tetrahedron 2002, 58, 5573–5590.
8. List, B.; Lerner, R. A.; Barbas, C. F., III. J. Am. Chem. Soc.
000, 122, 2395–2396.
References and notes
2
1
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9. For recent reviews, see: (a) Dalko, P. I.; Moisan, L. Angew.
Chem., Int. Ed. 2004, 43, 5138–5176; (b) Berkessel, A.;