the organic layer was separated and the aqueous layer was
extracted with dichloromethane (10 mL × 2). The organic layers
were combined and dried over anhydrous Na2SO4. After filtration
and concentration under reduced pressure, the crude product was
purified by preparative thin layer chromatography (benzene–ethyl
acetate = 20 : 1) to afford the desired product. The optical purity
was determined by HPLC analysis using a chiral column.8
S. Kobayashi, J. Am. Chem. Soc., 2005, 127, 15528; (e) S. Kobayashi,
Y. Hasegawa and H. Ishitani, Chem. Lett., 1998, 1131; (f) H. Ishitani,
T. Kitazawa and S. Kobayashi, Tetrahedron Lett., 1999, 40, 2161.
4 (a) S. Kobayashi, S. Komiyama and H. Ishitani, Angew. Chem., Int. Ed.,
1998, 37, 979; (b) S. Kobayashi, K. Kusakabe, S. Komiyama and H.
Ishitani, J. Org. Chem., 1999, 64, 4220; (c) S. Kobayashi, K. Kusakabe
and H. Ishitani, Org. Lett., 2000, 2, 1225; (d) Y. Yamashita, Y. Mizuki
and S. Kobayashi, Tetrahedron Lett., 2005, 46, 1803.
5 (a) H. Ishitani, S. Komiyama and S. Kobayashi, Angew. Chem., Int.
Ed., 1998, 37, 3186; (b) H. Ishitani, S. Komiyama, Y. Hasegawa and S.
Kobayashi, J. Am. Chem. Soc., 2000, 122, 762.
6 T. Gastner, H. Ishitani, R. Akiyama and S. Kobayashi, Angew. Chem.,
Int. Ed., 2001, 40, 1896.
7 (a) H. Ishitani, Y. Yamashita, H. Shimizu and S. Kobayashi, J. Am.
Chem. Soc., 2000, 122, 5403; (b) Y. Yamashita, H. Ishitani, H. Shimizu
and S. Kobayashi, J. Am. Chem. Soc., 2002, 124, 3292.
8 (a) Y. Yamashita, S. Saito, H. Ishitani and S. Kobayashi, Org. Lett.,
2002, 4, 1221; (b) Y. Yamashita, S. Saito, H. Ishitani and S. Kobayashi,
J. Am. Chem. Soc., 2003, 125, 3793.
9 (a) S. Kobayashi, H. Shimizu, Y. Yamashita, H. Ishitani and J.
Kobayashi, J. Am. Chem. Soc., 2002, 124, 13678; (b) Y. Yamashita
and S. Kobayashi, J. Am. Chem. Soc., 2004, 126, 11279.
(R)-2-Phenyl-2,3-dihydro-4H-pyran-4-one (5a). [a]2D6 −97.1 (c
1
0.69 in CHCl3, 97% ee). H NMR (600 MHz; solvent CDCl3;
standard Me4Si (0 ppm)) d 2.66 (dd, 1H), 2.90 (dd, 1H), 5.42
(dd, 1H), 5.52 (d, 1H), 7.3–7.4 (m, 5H), 7.48 (d, 1H). 13C NMR
(600 MHz; solvent CDCl3; standard CDCl3 (77.0 ppm)) d 43.3,
81.0, 107.3, 126.0, 128.8, 128.9, 137.8, 163.1, 192.1. HPLC (Daicel
Chiralcel OD, hexane–iPrOH = 40 : 1, flow rate = 1.0 mL min−1):
tR = 25.1 min (S), tR = 30.1 min (R). TLC Rf = 0.24 (benzene–
ethyl acetate = 20 : 1).
10 (a) M. Ueno, H. Ishitani and S. Kobayashi, Org. Lett., 2002, 4, 3395;
(b) S. Kobayashi, S. Saito, M. Ueno and Y. Yamashita, Chem. Commun.,
2003, 2016; (c) S. Kobayashi, M. Ueno, S. Saito, Y. Mizuki, H. Ishitani
and Y. Yamashita, Proc. Natl. Acad. Sci. U.S.A., 2004, 101, 5476.
11 K. Saruhashi and S. Kobayashi, J. Am. Chem. Soc., 2006, 128, 11232.
12 Recent reviews of Mukaiyama aldol reactions: Modern Aldol Reactions,
ed. R. Mahrwald, Wiley-VCH, Weinheim, Germany, 2004.
13 Recent examples of anti-selective aldol reactions: (a) N. Yoshikawa,
T. Suzuki and M. Shibasaki, J. Org. Chem., 2002, 67, 2556; (b) S. E.
Denmark and S. Fujimori, Org. Lett., 2002, 4, 3473; (c) T. Ooi, M.
Taniguchi, K. Doda and K. Maruoka, Adv. Synth. Catal., 2004, 346,
1073; (d) S. Saito and S. Kobayashi, J. Am. Chem. Soc., 2006, 128,
8704.
Acknowledgements
This work was partially supported by Grant-in-Aid for Scientific
Research from the Japan Society of the Promotion of Sciences
(JSPS).
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1350 | Org. Biomol. Chem., 2007, 5, 1347–1350
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