6452
Y. Wu, G. Liu / Tetrahedron Letters 52 (2011) 6450–6452
J. Org. Lett. 2000, 2, 2821–2824; (g) Ager, D. J.; Prakash, I.; Schaad, D. R. Chem. Rev.
1996, 96, 835–875; (h) Dyen, M. E.; Swern, D. Chem. Rev. 1967, 67, 197–246.
3. (a) Kawanami, H.; Ikushima, Y. Tetrahedron Lett. 2002, 43, 3841–3844; (b)
Hancock, M. T.; Pinhas, A. R. Tetrahedron Lett. 2003, 44, 5457–5460; (c) Miller, A.
W.; Nguyen, S. T. Org. Lett. 2004, 6, 2301–2304; (d) Du, Y.; Wu, Y.; Liu, A.-H.; He,
N.-L. J. Org. Chem. 2008, 73, 4709–4712; (e) Jiang, H.-F.; Ye, J.-W.; Qi, C.-R.;
Huang, L.-B. Tetrahedron Lett. 2010, 51, 928–932.
4. (a) Ochiai, B.; Yokota, K.; Fujii, A.; Nagai, D.; Endo, T. Macromolecules 2008, 41,
1229–1236; (b) Heldebrant, D. J.; Jessop, P. G.; Thomas, C. A.; Eckert, C. A.; Liotta,
C. L. J. Org. Chem. 2005, 70, 5335–5338; (c) Pérez, E. R.; Santos, R. H. A.;
Gambardella, M. T. P.; de Macedo, L. G. M.; Rodrigues-Filho, U. P.; Launay, J.-C.;
Franco, D. W. J. Org. Chem. 2004, 69, 8005–8011; (d) Hooker, J. M.; Reibel, A. T.;
Hill, S. M.; Schueller, M. J.; Fowler, J. S. Angew. Chem., Int. Ed. 2009, 48, 3482–
3485.
reaction time, or amount of the additives) did not give the satisfac-
tory result.
The detailed mechanism of this transformation is not clear at
moment. However, the low yield obtained in the absence of organ-
ocatalyst suggests that the organocatalyst DBN was involved in the
cycle of CO2 fixation. And a proposed mechanism was listed in
Scheme 1. After the rapid CO2 fixation by DBU, the bicarbonate salt
reacts with aziridine 1 to generate another bicarbonate salt. Then,
the ring opening of aziridinium promoted by LiI, and sequentially
intramolecular ring closure occurs to generate the target product 2.
In conclusion, an efficient and simple process for the fixation of
CO2 to aziridine was developed, in which the reaction was
achieved under 1 atm CO2 pressure by using DBN as the catalyst,
and LiI as an additive. Furthermore, this chemical fixation of CO2
could also be carried out at room temperature with longer reaction
time.
5. Synthesis of 2-oxazolidinone 2a–h: In
a sealed glass tube, the aziridine
(0.2 mmol) was added to a mixture solution of DBN (2.5 mg, 0.02 mmol), LiI
(5.4 mg, 0.04 mmol) in toluene (1.5 ml) under argon atmosphere. Tube was
then charged with carbon dioxide for three times. The reactions were carried
out for 5, 12, or 24 h at 90 °C, 50 °C, or room temperature. The reaction
mixture was purified directly by column chromatography on silica gel with a
gradient eluant of petroleum ether and ethyl acetate to afford the
corresponding cycloaddition products. Compound 2a: 1H NMR (400 MHz,
CDCl3) d 4.32 (t, J = 7.2 Hz, 2H), 3.57 (t, J = 7.2 Hz, 2H), 3.26 (t, J = 7.2 Hz, 2H),
1.54 (m, 2H), 1.36 (m, 2H), 0.95 (t, J = 7.2 Hz, 3H). 13C NMR (100 MHz, CDCl3) d
158.4, 61.6, 44.4, 43.8, 29.3, 19.7, 13.6. Compound 2b: 1H NMR (400 MHz,
CDCl3) d 7.32 (m, 5H), 4.43 (s, 2H), 4.30 (t, J = 7.2 Hz, 2H), 3.42 (t, J = 7.2 Hz,
2H). 13C NMR (100 MHz, CDCl3) d 158.5, 135.7, 128.7, 128.0, 127.9, 61.7, 48.3,
43.9. Compound 2c: 1H NMR (400 MHz, CDCl3) d 4.32 (t, J = 8.0 Hz, 2H), 3.71 (s,
3H), 3.64 (t, J = 8.0 Hz, 2H), 3.57 (t, J = 6.4 Hz, 2H), 2.63 (t, J = 6.4 Hz, 2H). 13C
NMR (100 MHz, CDCl3) d 171.9, 158.3, 61.8, 51.8, 45.2, 40.0, 32.5. HRMS: m/z
(ESI) calcd [M+Na]+ 196.05803, measured 196.05817. Compound 2d: 1H NMR
(400 MHz, CDCl3) d 4.32 (dt, J = 9.2, 2.8 Hz, 2H), 3.71 (s, 3H), 3.60 (t, J = 7.8 Hz,
2H), 3.43 (ddd, J = 31.8, 28.4, 8.4 Hz, 2H), 2.82 (m, 1H) 1.21 (d, J = 7.2 Hz). 13C
NMR (100 MHz, CDCl3) d 175.1, 158.6, 61.8, 52.0, 47.2, 45.4, 38.4, 14.7. HRMS:
m/z (ESI) calcd [M+Na]+ 210.07368, measured 210.07381. Compound 2e: 1H
NMR (400 MHz, CDCl3) d 4.31 (t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 3.55 (t,
J = 4.8 Hz, 2H), 3.43 (t, J = 4.8 Hz, 2H), 3.34 (s, 3H). 13C NMR (100 MHz, CDCl3) d
158.6, 71.0, 61.9, 58.7, 45.9, 44.1, 29.6. Compounds 2g and 2g0: 1H NMR
(400 MHz, CDCl3) d 4.68–4.59 (m, 0.58H), 4.40 (t, J = 8 Hz, 0.42H), 3.92–3.81
(m, 0.84H), 3.64 (t, J = 8.4 Hz, 0.58H), 3.44–3.36 (m, 0.42H), 3.28–3.19 (m,
1.16H), 3.13–3.08 (m, 0.58H), 3.08–3.01 (m, 0.42H), 1.57–1.50 (m, 2H), 1.43 (d,
J = 6.0 Hz, 1.26H), 1.39–1.30 (m, 6H), 1.27 (d, J = 6.0 Hz, 1.74H), 0.90 (t,
J = 6.4 Hz, 3H). Compounds 2h and 2h0: 1H NMR (400 MHz, CDCl3) d 4.67–4.59
(m, 0.53H), 4.40 (t, J = 8 Hz, 0.47H), 3.97–3.82 (m, 0.47H), 3.86–3.82 (m,
0.53H), 3.707 (s, 1.59H), 3.701 (s, 1.41H), 3.20–3.15 (m, 1H), 2.72–2.36 (m, 4H),
1.42 (d, J = 6.4 Hz, 1.59H), 1.30 (d, J = 6.4 Hz, 1.41H).
Acknowledgment
We thank the National Basic Research Program of China (973-
2009CB825300) and the Science and Technology Commission of
the Shanghai Municipality (08dj1400100) for financial support.
References and notes
1. (a) Sun, J.; Ren, J.; Zhang, S.; Cheng, W. Tetrahedron Lett. 2009, 50, 423–426; (b)
Shen, Y. M.; Duan, W. L.; Shi, M. Eur. J. Org. Chem. 2004, 3080–3089; (c) Lu, X.-B.;
Zhang, Y.-J.; Jin, K.; Luo, L.-M.; Wang, H. J. Catal. 2004, 227, 537–541; (d) Shen, Y.
M.; Duan, W. L.; Shi, M. J. Org. Chem. 2003, 68, 1559–1562; (e) Darensbourg, D. J.;
Lewis, S. J.; Rodgers, J. L.; Yarbrough, J. C. Inorg. Chem. 2003, 42, 581–589; (f)
Calo, V.; Nacci, A.; Monopoli, A.; Fanizzi, A. Org. Lett. 2002, 4, 2561–2563; (g)
Paddock, R. M.; Nguyen, S. B. T. J. Am. Chem. Soc. 2001, 123, 11498–11499.
2. (a) Park, C. S.; Kim, M. S.; Sim, T. B.; Pyun, D. K.; Lee, C. H.; Choi, D.; Lee, W. K. J. Org.
Chem. 2003, 68, 43–49; (b) Sim, T. B.; Kang, S. H.; Lee, K. S.; Lee, W. K. J. Org. Chem.
2003, 68, 104–108; (c) Katz, S. J.; Bergmeier, S. C. Tetrahedron Lett. 2002, 43, 557–
559; (d) Murakata, M.; Tsutsui, H.; Hoshino, O. Org. Lett. 2001, 3, 299–302; (e)
Cacchi, S.; Fabrizi, G.; Goggiamani, A.; Zappia, G. Org. Lett. 2001, 3, 2539–2541; (f)
Barta, N. S.; Sidler, D. R.; Somerville, K. B.; Weissman, S. A.; Larsen, R. D.; Reider, P.