J. CHEM. RESEARCH (S), 1999 489
Na2SO4. After removal of the solvent at reduced pressure, the
residue was chromatographed on silica gel (light petroleum±ethyl
acetate; 8:1 v/v) to give a low melting point compound 8 (0.374 g,
After completion of the reaction, H2O (5 ml) was added, and the
resultant mixture extracted with acetate (15 ml  3); the organic layer
was then washed with H2O and brine respectively. Evaporation and
chromatography of the residue using light petroleum^acetate (9:1,
v/v) as eluant gave 15 as a colorless oil (0.093 g, 90%). Its isomer
20
42%), and (S)-7 (0.351 g, 45%). (S)-7 a
19:18 (c, 0.86, CHCl3);
D
20
D
(lit.8 a
20:88 (c. 1.27 CHCl3); other spectra data was same as
1
6. Compound 8 (two isomers were obtained in ratio of 3:1, the data
12 was prepared in a similar way. nmax=cm (KBr) 3048, 2981, 1744,
of the major product is reported here): nmax=cm (KBr) 3388, 2982,
1375, 1140, 1100; m/z (EI) 201 (M
45), 113; dH (2H6acetone) 1.08
1
1696, 1629; m/z (EI) 128 (M ), 111, 84 (base); dH (2H6 acetone)
(3 H, t, J 7:0 Hz), 1.20^1.31 (6 H, m), 2.05 (3 H, s); 4.83^5.01 (2 H,
m), 5.18^5.24 (1 H, m), 5.80 (2 H, J 9:7 Hz); (Found: C, 59.10:
H, 8.30. C12H20O5 requires C, 59.00; H, 8.25%.) The spectra data
of 15 were the same as those for 12.
1.23 (3 H, d, J 6:7 Hz), 3.46 (s, OH), 4.63 (1 H, q, J 6:7 Hz), 5.23
(1 H, d, J 3:2 Hz), 5.98 (1 H, d, J 10:2 Hz), 6.99 (1 H, dd,
J 10:2 , 3.2 Hz). (Found: C, 56.32; H, 6.31. C6H8O3 requires C,
56.25; H, 6.29%.)
(4S,5R)-O-Acetylosmundalactone 4 and its Isomer 2.ö Compound
15 (0.055 g, 0.223 mmol) was dissolved in acetic acid 92 ml). A sol-
ution of CrO3 (0.022 g, 0.022 mmol) in acetic acid (2 ml) was added
to it very slowly. The reaction was monitored by TLC; after
completion of the reaction, the mixture was poured into H2O (4 ml),
extracted with diethyl ether, and the organic layer was successively
washed with saturated NaHCO3 and brine, and then dried over
Na2SO4. The solvent was then removed at reduced pressure, the resi-
due was puri¢ed through column chromatography using light
petroleum^acetate (8:1, v/v) as eluant, to give compound 4 as a
colorless oil in 70% yield. The isomer 2 was prepared in a similar way.
(S)-6-Hydroxy-2-methyl-2,6-dihydropyran-3-one 9.öThe alcohol
6 (0.323 g, 2.88 mmol) was dissolved in 10 ml THF:H2O ꢀ4:1, v/v),
NBS (0.513 g, 2.88 mmol) was added portionwise. The reaction
was monitored by TLC, then quenched with 10% KI (1.0 ml) followed
by 15% Na2S2O4 (0.2 ml); the mixture was then stirred until the color
turned yellowish, then neutralized by saturated NaHCO3, extracted
with diethyl ether and dried over Na2SO4. Evaporation and
chromatography of the residue using light petroleum^acetate (8:1,
v/v) as eluant gave the ketone 9 (two isomers were obtained in ratio
of 3:1) (0.310 g, 84%). Other spectral data were same as these com-
pound for 8.
20
1
Compound 4: a 1608 (c. 2.6, CHCl3); nmax=cm (KBr) 3050,
D
(2R)-6-(1-Ethoxyethyl)-2-methyl-2,6-dihydropyran-3-one 13 and
its Isomer 10.öTo a solution of 8 (0.387 g, 2.87 mmol) in CH2Cl2
(15 ml) was added ethyl vinyl ether (2.064 g, 2.74 ml, 28.7 mmol)
and cat. PPTS. The mixture was stirred for 1.5 h, then H2O (5 ml)
was added, extracted by CH2Cl2, (15 ml  3), and dried over
Na2SO4. After removal of the solvent, the residue was puri¢ed
through column chromatography using light petroleum^acetate
(15:1, v/v) to give the pure 13 as a yellowish oil (0.493 g, 86%).
2987, 1733, 1634, 1450, 1377; m/z (EI) 126 (M
44), 84, 56; dH
(CDCl3) 1.26 (3 H, d, J 6:6 Hz), 1.97 (3 H, s), 4.44 (1 H, p,
J 6:6 Hz); 5.12, ddd, J 6:6, 3.3, 1.3 Hz), 5.93 (1 H, d,
20
J 10:0 Hz), 6.66 (1 H, dd J 10:0, 3.3 Hz); isomer 2 a
1618
D
20
(c. 2.7, CHCl3 lit.2 a
1728 (c. 2.8, CHCl3). (Found: C, 56.50;
H, 6.00. C8H10O4 requDires C, 56.47; H, 5.92%). Other spectral data
were identical with those for compound 4.
1
The isomer 10 was prepared in the similar way. nmax=cm (KBr)
Support from the National Natural Science Foundation
of China is gratefully acknowledged.
3052, 2983, 1701, 1630, 1141, 1083; m/z (EI) 155(M
45; dH
ꢀ2H6acetone) 1.11 (3 H, t, J 7:0 Hz), 1.32^1.41 (6 H, m), 3.36^3.72
(2 H, m), 4.44^4.62 (1 H, m), 4.86^5.02 (1 H, m), 5.37^5.54 (1 H, m),
5.94^6.07 (1 H, d, J 10:2 Hz), 6.77 (1 H, dd, J 10:2, 3.2 Hz).
(Found: C, 60.03, H, 8.10, C10H16O4 requires C, 59.98; H, 8.06%.)
The spectra data of 10, were identical with those for 13.
Received, 10th February 1999; Accepted, 29th April 1999
Paper E/9/01144G
(2R,3S)-6-(1-Ethoxyethyl)-2-methyl-3,6-dihydro-3-alcohol 14 and
its Isomer 11.öAt 40 8C, NaBH4 was added portionwise to a
solution of 14 (0.466 g, 2.33 mmol) in methanol (6 ml) containing
CeCl3 Á7H2O (0.867 g, 2.33 mmol). The reaction was monitored by
TLC. The reaction quenched with H2O (5 ml) and extracted with
diethyl ether ꢀ20 ml  3, the ether layer was washed with brine dried
over Na2SO4. The alcohol 14 was obtained quantitatively as a
colorless oil. The synthesis of its isomer 11 was performed in a similar
References
1
2
3
4
5
6
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1
way. nmax=cm (KBr) 3427, 3045, 1658, 1380, 1142, 1096; m/z (EI)
157 (M
45, 113; dH (2H6acetone) 1.08 (3 H t, J 7:0 Hz),
1.19^1.29 (6 H, m), 2.96 (OH); 3.46^3.74 (4 H, m), 4.80 (1 H, q,
J 5:4 Hz), 5.08^5.17 (1 H, m), 5.66^5.75 (1 H, m), 5.90 (1 H, d,
J 10:4 Hz); (Found: C, 59.42; H, 8.10. C10H18O4 requires C, 59.39,
H, 8.97%.) The spectra data of 14 were same as those for 11.
(2R,3S)-3-Acetoxyl-6-(1-ethoxyethyl)-2-methyl-3,6-dihydropyran
15 and its Isomer 12.öTo a solution of 14 (0.086 g, 0.426 mmol)
in pyridine (2 ml) was added acetic anhydride (0.065 g, 0.63 mmol)
and cat. DMAP, the mixture was stirred for 3 h at room temperature.