L.-J. Chen et al. / Tetrahedron Letters 48 (2007) 3475–3477
3477
C20,6d so we got a mixture of 21a-methyl and
21b-methyl steroids. The mixture appears a single point
on thin layer chromatography and is inseparable. The
C-22 carbonyl group of 9 was protected by ethylene
glycol ketal6d,10 to give 20-epimers. Fortunately, the
two isomers of 10 could be separated by simple recrys-
tallization. We performed similar transformations
according to the literature,3,6d that is, conversion of
3-OAc in 10 to 3-OTBS in 11, dihydroxylation of the
16,17-alkene function in 11 with OsO4, Swern oxidation
of the 16a-OH group in 12, and stereoselective reduction
of the 16-keto group in 13 to the 16b-OH group in 14.
Thus, the protected aglycone of 5(6)-dihydro-OSW-1
was synthesized with 13 steps in 9.0% overall yield.
The glycosylation of aglycone 13 with disaccharide
trichloroacetimidate 1611 in the presence of TMSOTf
provided the corresponding protected 5(6)-dihydro-
OSW-1 15 in 80% yield. Removal of all of the protecting
groups in AcOH/H2O (v/v = 3:1) at 70 °C afforded the
desired 5(6)-dihydro-OSW-1 (1) in 60.2% yield. Its spec-
tral data are identical with that of reported in the
literature.3,12
Tetrahedron Lett. 2000, 41, 3751; (d) Yu, W.; Jin, Z. J.
Am. Chem. Soc. 2001, 123, 3369; (e) Yu, W.; Jin, Z. J. Am.
Chem. Soc. 2002, 124, 6576.
5. (a) Marker, R. E. J. Am. Chem. Soc. 1940, 62, 3350; (b)
Rosenkranz, G.; Mancera, O.; Sondheimer, F.; Djerassi,
C. J. Org. Chem. 1956, 21, 520.
6. (a) Tian, W. S. Acta Chim. Sinica 1992, 50, 72; (b) Tian,
W. S.; Guan, H. P.; Pan, X. F. Chin. Chem. Lett. 1994, 5,
1013; (c) Tian, W. S.; Guan, H. P.; Pan, X. F. Chin. J.
Chem. 2003, 21, 793; (d) Xu, Q. H.; Peng, X. W.; Tian, W.
S. Tetrahedron Lett. 2003, 44, 9375; (e) Tian, W. S.; Xu, Q.
H.; Chen, L.; Zhao, C. F. Sci. China, Ser. B: Chem. 2004,
47, 142; (f) Qin, H. J.; Tian, W. S.; Lin, C. W. Tetrahedron
Lett. 2006, 47, 3217.
7. Trost, B. M. Acc. Chem. Res. 2002, 35, 695.
8. Tian, W. S.; Wang, J.; Xu, Q. H.; Lin, J. R. China Patent
200610029252.2, 2006.
9. Arthur, F. K.; Michael, L. M.; Leslie, G. P. J. Org. Chem.
1985, 50, 2359.
10. (a) Guo, C. X.; Fuchs, P. L. Tetrahedron Lett. 1998, 39,
1099; (b) Deng, S. J.; Yu, B.; Lou, Y.; Hui, Y. Z. J. Org.
Chem. 1999, 64, 202.
11. Disaccharide trichloroacetimidate 16 was synthesized
according to the methods reported in Ref. 4.
12. Analytical data for our synthesized 5(6)-dihydro-OSW-1
25
(1): ½aꢁD ꢀ18.3 (c 0.38, CH3OH, lit.3 ꢀ12.6 (c 0.8,
CH3OH)); 1H NMR (500 MHz, C5D5N): d 8.40 (d,
J = 8.6 Hz, 2H), 7.16 (d, J = 8.6 Hz, 2H), 5.76 (t,
J = 8.2 Hz, 1H), 5.63 (t, 1H), 5.20 (d, J = 7.6 Hz, 1H),
4.87 (s, 1H), 4.67 (d, J = 6.0 Hz, 1H), 4.47 (br s, 1H), 4.32–
4.22 (m, 6H), 3.83 (s, 3H), 3.25 (q, J = 7.6 Hz, 1H), 2.12 (s,
3H), 1.35 (d, J = 7.2 Hz, 3H), 1.05 (s, 3H), 0.96 (d,
References and notes
1. Kubo, S.; Mimaki, Y.; Terao, M.; Sashida, Y.; Nikaida,
T.; Ohmato, T. Phytochemistry 1992, 31, 3969.
2. Mimaki, Y.; Kuroda, M.; Kameyama, A.; Sashida, Y.;
Hirano, T.; Oka, K.; Maekawa, R.; Wada, T.; Sugita,
K.; Beutler, A. J. Bioorg. Med. Chem. Lett. 1997, 7,
633.
3. Deng, L.; Wu, H.; Yu, B.; Jiang, M.; Wu, J. Chin. J.
Chem. 2004, 22, 994.
4. (a) Guo, C.; Fuchs, P. L. Tetrahedron Lett. 1998, 39, 1099;
(b) Deng, S.; Yu, B.; Hui, Y. J. Org. Chem. 1999, 64, 202;
(c) Morzychi, J. W.; Gryszkiewicz, A.; Jastrzebska, I.
J = 7.2 Hz, 3H), 0.94 (d, J = 7.2 Hz, 3H), 0.91 (s, 3H). 13
C
NMR (125 MHz, C5D5N): d 219.05, 169.38, 165.55,
164.01, 132.54, 114.37, 114.24, 103.79, 100.95, 88.51,
85.78, 81.10, 76.46, 75.25, 72.18, 70.83, 70.76, 67.16,
55.61, 54.31, 48.27, 47.00, 46.45, 45.29, 39.44, 39.38, 37.57,
35.90, 35.64, 33.07, 32.81, 32.61, 29.22, 27.84, 22.93, 22.59,
21.01, 14.03, 12.61, 11.95; MS (ESI): 897 (M+Na+), 874
(M+).