Y. K. Kang et al. / Tetrahedron Letters 53 (2012) 3811–3814
3813
Table 3
Catalytic enantioselective chlorination of b-keto esters 1a,b
O
O
O
O
O
Cl
Cl
Cl
cat. 4d (0.5 mol%)
+
R1
Ot-Bu
R1
Ot-Bu
*
Cl
Cl
°
DCM, -20 C
R2
Cl
R2
Cl
3
1
2
O
O
O
CO2Et
Cl
CO2Me
Cl
CO2t-Bu
*
Cl
3a
, 20 h, 93%, 60% ee
3b
3e
3c
24 h, 95%, 27% ee
O
, 10 h, 93%, 92% ee
Cl
O
CO2t-Bu
CO2t-Bu
Cl
CO2t-Bu
Cl
*
*
*
O
O
3d, 1 d, 95%, 92% ee
, 2.5 d, 95%, 91% ee
O
3f
, 2 d, 95%, 87% ee
O
O
O
CO2t-Bu
CO2t-Bu
*
*
OEt
Cl
Cl
Cl
3g, 1 d, 95%, 94% ee
Isolated yield.
3i, 1.5 d, 85%, 21% ee
3h, 1.5 d, 95%, 86% ee
a
b
Enantiopurity was determined by HPLC analysis using chiralcel OJ-H (for 3a, 3i), chiralpak AS-H (for 3b), and IC (for 3c–h) columns.
O
O
O
O
O
Oestreich, M. Angew. Chem., Int. Ed. 2005, 44, 2324; (f) Pihko, P. M. Angew.
Chem., Int. Ed. 2006, 45, 544; (g) Bobbio, C.; Gouverneur, V. Org. Biomol. Chem.
2006, 2065; (h) Hamashima, Y.; Sodeoka, M. Synlett 2006, 1467; (i) Lectard, S.;
Hamashima, Y.; Sodeoka, M. Adv. Synth. Catal. 2010, 352, 2708; (j) Kang, Y. K.;
Kim, D. Y. Curr. Org. Chem. 2010, 14, 917; (k) Cahard, D.; Xu, X.; Couve-Bonnaire,
S.; Pannecoucke, X. Chem. Soc. Rev. 2010, 39, 558.
Cl
Cl
Cl
cat. 4d (0.5 mol%)
DCM, -20 C, 24 h
+
Cl
Cl
Cl
°
Cl
2
6a
, 85%, 47% ee
5a
4. For reviews on asymmetric halogenation using organocatalysts, see: (a)
Guillena, G.; Ramon, D. J. Tetrahedron: Asymmetry 2006, 17, 1465; (b) Marigo,
M.; Jørgensen, K. A. Chem. Commun. 2001, 2006; (c) Ueda, M.; Kano, T.;
Maruoka, K. Org. Biomol. Chem. 2005, 2009, 7.
Scheme 1. Catalytic enantioselective chlorination of cyclic 1,3-diketone 5a.
5. For selected examples for fluorination reactions, see: (a) Hintermann, L.; Togni,
A. Angew. Chem., Int. Ed. 2000, 39, 4359; (b) Cahard, D.; Audouard, C.;
Plaquevent, J.; Roques, N. Org. Lett. 2000, 2, 3699; (c) Mohar, B.; Baudoux, J.;
Plaquevent, J.-C.; Cahard, D. Angew. Chem., Int. Ed. 2001, 40, 4214; (d) Shibata,
N.; Suzuki, E.; Takeuchi, Y. J. Am. Chem. Soc. 2000, 122, 10728; (e) Shibata, N.;
Suzuki, E.; Asahi, T.; Shiro, M. J. Am. Chem. Soc. 2001, 123, 7001; (f) Hamashima,
Y.; Yagi, K.; Takano, H.; Tamá s, L.; Sodeoka, M. J. Am. Chem. Soc. 2002, 124,
14530; (g) Kim, D. Y.; Park, E. J. Org. Lett. 2002, 4, 545; (h) Greedy, B.; Paris, J.-
M.; Vidal, T.; Gouverneur, V. Angew. Chem., Int. Ed. 2003, 42, 3291; (i) Shibata,
N.; Kohno, J.; Takai, K.; Ishimaru, T.; Nakamura, S.; Toru, T.; Kanemasa, S.
Angew. Chem., Int. Ed. 2005, 44, 4204; (j) Marigo, M.; Fielenbach, D.; Braunton,
A.; Kjasgaard, A.; Jorgensen, K. A. Angew. Chem., Int. Ed. 2005, 44, 3703; (k)
Steiner, D. D.; Mase, N.; Barbas, C. F., III Angew. Chem., Int. Ed. 2005, 44, 3706; (l)
Beeson, T. D.; MacMillan, D. W. C. J. Am. Chem. Soc. 2005, 127, 8826.
P
P
Pd
O
O
RO
Cl+
6. For selected examples for chlorination and bromination reactions, see: (a)
Wack, H.; Taggi, A. E.; Hafez, A. M.; Drury, W. J.; Lectka, T. J. Am. Chem. Soc.
2001, 123, 1531; (b) Hafez, A. M.; Taggi, A. E.; Wack, H.; Esterbrook, J.; Lectka, T.
Org. Lett. 2001, 3, 2049; (c) Halland, N.; Braunton, A.; Bachmann, S.; Marigo, M.;
Jorgensen, K. A. J. Am. Chem. Soc. 2004, 126, 4790; (d) Marigo, M.; Bachmann, S.;
Halland, N.; Braunton, A.; Jorgensen, K. A. Angew. Chem., Int. Ed. 2004, 43, 5507;
(e) Brochu, M. P.; Brown, S. P.; MacMillan, D. W. C. J. Am. Chem. Soc. 2004, 126,
4108; (f) France, S.; Wack, H.; Taggi, A. E.; Hafez, A. M.; Wagerle, T. R.; Shah, M.
H.; Dusich, C. L.; Lectka, T. J. Am. Chem. Soc. 2004, 126, 4245; (g) Zhang, Y.;
Shibatomi, K.; Yamamoto, H. J. Am. Chem. Soc. 2004, 126, 15038; (h) Ibrahim, H.;
Kleinbeck, F.; Togni, A. Helv. Chim. Acta 2004, 87, 605; (i) Bernardi, L.; Jorgensen,
K. A. Chem. Commun. 2005, 1324; (j) Amatore, M.; Beeson, T. D.; Brown, S. P.;
MacMillan, D. W. C. Angew. Chem., Int. Ed. 2009, 48, 5121; (k) Frings, M.; Bolm,
C. Eur. J. Org. Chem. 2009, 4085; (l) Zheng, W.; Zhang, Z.; Kaplan, M. J.; Antilla, J.
C. J. Am. Chem. Soc. 2011, 133, 3339.
Figure 2. Plausible transition state model.
References and notes
1. (a) Ojima, I.; McCarthy, J. R.; Welch, J. T. Biomedical Frontiers of Fluorine
Chemistry, ACS Symposium Series 639; American Chemical Society: Washington,
DC, 1996; (b) Thomas, G. Medicinal Chemistry: An Introduction; John Wiley &
Sons: New York, 2000.
2. (a) De Kimpe, N.; Verhe, R. The Chemistry of
a-Haloketones, a-Haloaldehydes, and
a
-Haloimines; John Wiley & Sons: New York, 1988; (b) Ramachandran, P. V.
Asymmetric Fluoroorganic Chemistry: Synthesis, Applications, and Future
Directions, ACS Symposium Series 746; American Chemical Society:
Washington, DC, 2000; (c) Czekelius, C.; Tzschucke, C. C. Synthesis 2010, 543.
3. For reviews on asymmetric halogenation using metal complexes, see: (a)
Muniz, K. Angew. Chem., Int. Ed. 2001, 40, 1653; (b) Ma, J. A.; Cahard, D. Chem.
Rev. 2004, 104, 6119; (c) Ibrahim, H.; Togni, A. Chem. Commun. 2004, 1147; (d)
France, S.; Weatherwax, A.; Lectka, T. Eur. J. Org. Chem. 2005, 3, 475; (e)
7. Hintermann, L.; Togni, A. Helv. Chim. Acta 2000, 83, 2425.
8. For chlorination using metal complexes, see: (a) Marigo, M.; Kumaragurubaran,
N.; Jørgensen, K. A. Chem. Eur. J. 2004, 10, 2133; (b) Qi, M.-H.; Wang, F.-J.; Shi,
M. Tetrahedron:Asymmetry 2010, 21, 247; (c) Kawatsura, M.; Hayashi, S.;
Komatsu, Y.; Hayase, S.; Itoh, T. Chem. Lett. 2010, 39, 466; (d) Hamashima, Y.;
Nagi, T.; Shimizu, R.; Tsuchimoto, T.; Sodeoka, M. Eur. J. Org. Chem. 2011, 3675.