J. CHEM. RESEARCH (S), 1998 561
with methanol, water was added and the product extracted with
ether. Evaporation of the ether yielded a residue (34 mg) which was
chromatographed over silica gel. Elution with 1% ether in hexane
aorded compound 8, mp 152±153 8C (11 mg, 60%); [ꢀ]D1008
Experimental
Mps were measured with a Ko¯er hot-stage apparatus and are
uncorrected. NMR spectra were recorded with a Bruker AM-300
spectrometer for solutions in CDCl3, mass spectra with a Kratos
MS25RFA at 70 eV using a direct inlet system. Rotations were
measured at 23 8C with a Zeiss `0.018' polarimeter. Merck silica gel
(70±230 mesh ASTM) was used for column chromatography. TLC
was performed on Merck silica gel 60 G254 and the spots were
observed either by exposure to iodine vapour or by UV light. All
organic extracts were dried over anhydrous sodium sulfate and
evaporated under reduced pressure below 60 8C.
(c 0.3, CHCl3); m/z 248 (M ); ꢁH (300 MHz) 0.89 (3 H, s, Me), 0.93
(3 H, s, Me), 1.21 (3 H, s, Me) and 2.3±2.6 (2 H, m,
7-H); ꢁC (75.45 MHz) 17.62, 18.11, 20.39, 21.36, 22.42, 33.27, 33.29,
34.47, 38.48, 41.39, 51.56, 143.22 (C-8 or C-9), 153.49 (C-9 or C-8),
163.24 (C-11 or C-12) and 164.84 (C-12 or C-11). Further elution
with 20% ether in hexane aorded starting material (15 mg).
We thank Dr. Bernardo Mendez for the measurement of
1
Photo-oxygenation of the Furan 5.ÐA solution of the furan 5
(80 mg, 0.36 mmol) in tert-butyl alcohol±2,6-lutidine (27 ml, 2:1)
containing eosin (2.6 mg) was irradiated at 15 8C with an external
150 W tungsten lamp for 6 h during which time oxygen was bubbled
through the reaction mixture. The solvent was evaporated under
reduced pressure and the residue chromatographed over silica gel.
Elution with 30% diethyl ether in hexane aorded a 2:1 mixture
of compounds 6a and 7, as an oil, as evidenced by the 1H NMR
spectrum. Crystallisation from hexane gave pure compound 6a, mp
172±175 8C (44 mg, 50% yield); [ꢀ]D1078 (c 1.7, CHCl3); m/z 250
the 2-D H and 13C NMR spectra.
Received, 27th April 1998; Accepted, 13th May 1998
Paper E/8/03123A
References
1 T. Nakano, in Studies in Natural Products Chemistry, ed. Atta-ur-
Rahman, Elsevier, Amsterdam, 1989, vol. 4, p. 403 and refs.
therein.
2 T. Nakano, J. Villamizar and M. A. Maillo, J. Chem. Res. (S),
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3 T. Nakano, J. Villamizar and M. A. Maillo, 20th IUPAC
Symposium on the Chemistry of Natural Products, Chicago, IL,
September 15-20, 1996.
4 T. Nakano and A. Martõn, J. Chem. Res. (S), 1989, 52.
5 T. Nakano, M. A. Maillo and A. Rojas, J. Chem. Soc., Perkin
Trans. 1, 1987, 2137.
6 S. V. Ley and M. Mahon, J. Chem. Soc., Perkin Trans. 1, 1983,
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7 H. H. Appel, R. P. M. Bond and K. H. Overton, Tetrahedron,
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8 A. Montagnac, M-T. Martin, C. Debitus and M. Pais, J. Nat.
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9 K. Bowden, I. M. Heibron, E. R. H. Jones and B. C. Weedon,
J. Chem. Soc., 1946, 39.
(M ); ꢁH (300 MHz) 0.89 (3 H, s, 14-Me), 0.90 (3 H, s, 15-Me),
1.23 (3 H, s, 13-Me), 4.00 (1 H, OH-11) and 6.04 (1 H, m, H-11);
ꢁC (75.45 MHz) 35.27 (C-1), 17.89 (C-2), 41.69 (C-3), 33.44 (C-4),
51.51 (C-5), 18.28 (C-6), 21.19 (C-7), 127.63 (C-8), 168.49 (C-9),
36.82 (C-10), 97.51 (C-11), 172.18 (C-12), 19.60 (C-13), 21.59 (C-14)
and 33.35 (C-15).
Chromatography of the mother-liquor of compound 6a over
silica gel with hexane±ether aorded pure compound 7 as an oil;
[a]D328 (c 1.8, CHCl3); m/z 250 (M ); dH (300 MHz) 0.85 (3 H, s,
Me), 0.90 (3 H, s, Me), 1.10 (3 H, s, 13-Me) and 5.83 (1 H, s,
H-12); dC (75.45 MHz) 34.90 (C-1), 17.81 (C-2), 41.68 (C-3), 34.18
(C-4), 52.08 (C-5), 18.33 (C-6), 24.13 (C-7), 168.18 (C-8), 138.48
(C-9), 34.66 (C-10), 170.35 (C-11), 96.84 (C-12), 20.15 (C-13), 21.47
(C-14) and 33.43 (C-15) (Found: C, 71.63; H, 8.55. C15H22O3
requires C, 71.97; H, 8.86%).
Oxidation of Compound 7.ÐThe Jones's reagent was added drop-
wise to a solution of compound 7 (38 mg) in acetone (3 ml) at room
temperature during 15 min. After decomposing the excess of reagent