Molecules 2007, 12
279
dried over anhydrous MgSO
4
, filtered and the solvent was removed under vacuum. The product was
purified by flash chromatography on silica gel column using hexane-ethyl acetate (2:1) as eluent to
1
afford a white amorphous solid: 72% yield; m.p.: 136-138°C; H-NMR (CDCl ) δ (ppm): 1.36-1.42
3
(
m, 1H), 1.50 (d, J = 11 Hz, 1H), 1.59-1.67 (m, 3H), 1.97 (ddd, J = 17.8/6.5/3.2 Hz, 1H), 2.13 (d, J =
1 Hz, 1H), 2.30 (m, 1H), 2.36 (m, 1H), 2.61 (broad signal, -OH), 2.90 (m, 1H), 3.95 (dd, J = 17.8/7.8
1
1
3
Hz, 1H), 4.15 (m, 1H), 4.22 (d, J = 2.0 Hz, 1H), 4.54 (d, J = 5 Hz, 1H); C- NMR (CDCl ) δ (ppm):
3
2
6.1 (CH
2 2 2
), 26.7 (CH ), 35.4 (CH ), 39.5 (CH), 42.9 (CH), 44.2 (CH), 49.1 (CH), 56.5 (CH), 69.7
-1
+ 81
(
(
CH), 76.1 (CH), 88.7 (CH); IR (KBr) ν (cm ): 3269, 2975-2869; MS m/z: 260 [(M + 2) , Br], 258
M , Br), 242 [(M – H O + 2) , Br], 240 [(M – H O) , Br].
+
79
+
81
+ 79
2
2
2
,7
Synthesis of rel-(1S,3S,7S,2R,8R)-6-oxo-3-(3,4,5-trimethoxyphenylcarbonyloxy) tricyclo[6.2.1.0 ]-
2
,7
undec-9-ene (12) and rel- (1S,2S,6S,8S,7R,9R)-6,9-epoxytricyclo[6.2.1.0 ]undecan-3-one (13)
Under a nitrogen atmosphere, thionyl chloride (0.270 mL; 3.6 mmol) was added to a solution of
3
,4,5-trimethoxybenzoic acid (0.385 g; 1.8 mmol) in CH Cl (5.5 mL). The mixture was refluxed for 4
2 2
hours. After evaporation of the solvent under reduced pressure the acid chloride 11 was dissolved in
anhydrous toluene (5.5 mL). To this solution it was added compound 10 (0.318 g, 1.8 mmol) and
pyridine (5.0 mL) and the mixture was refluxed during 24 hours. The reaction was monitored by TLC
and after completion it was diluted with dichloromethane and the resulting solution was washed with a
4 2 4
saturated solution of CuSO . The organic layer was dried over anhydrous Na SO and concentrated
under reduced pressure. The products were purified by silica gel column chromatography using
1
hexane-ethyl acetate (1:1) as eluent. Compound 12: white solid: 15% yield; m.p.: 42-46 °C; H-NMR
(CDCl
3
) δ (ppm): 1.26 (d, J = 8.4 Hz, 1H), 1.37 (d, J = 8.4 Hz, 1H), 1.92-2.05 (m, 2H), 2.16-2.29 (m,
2
1
4
H), 2.91-3.03 (m, 3H), 3.24 (broad signal, 1H), 3.83 (s, 9H), 5.52 (m, 1H), 5.93 (dd, J = 5.3/2.7 Hz,
1
3
H), 6.12 (dd, J = 5.3/2.9 Hz, 1H), 7,21 (s, 2H); C-NMR (CDCl
3
2 2
) δ (ppm): 25.6 (CH ), 35.6 (CH ),
4.4 (CH), 45.0 (CH), 45.4 (CH), 49.6 (CH ), 51.7 (CH), 56.1 (CH
2
3
), 60.8 (CH ), 70.0 (CH), 106.8
3
(
CH), 125.0 (C), 135.4 (CH), 135.8 (CH), 142.2 (C), 152.9 (C), 165.1 (C), 211.5 (C=O). Compound
1
1
1
2
1
3: colorless oil: 9 % yield; H-NMR (CDCl
3
) δ (ppm): 1.31 (d, J = 10.4, 1H), 1.35 (d, J = 3.2 Hz,
H), 1.44 (m, 1H), 1.50 (m, 1H), 1.82 (tdd, J = 13.0/13.0/5.4/1.3 Hz, 1H), 2.12 (m, 1H), 2.19 (m, 1H),
.26 (d, J = 5.4 Hz, 1H), 2.37-2.58 (m, 3H), 2.89 (t, J = 4.0 Hz, 1H), 4.22 (m, 1H), 4.40 (t, J = 6.3 Hz,
1
3
H); C-NMR (CDCl
3
) δ (ppm): 26.5 (CH
2
), 35.1 (CH
2
), 37.2 (CH
2
), 37.4 (CH
2
), 39.3 (CH), 43.5
+
(CH), 49.1 (CH), 51.2 (CH), 74.4 (CH), 79.7 (CH), 214.0 (C=O); MS m/z: 178 [M ].
2
,7 2,10
Synthesis of 6,9-epoxytetracyclo[6.2.1.0 .0 ]undecan-3-one (15)
A solution of compound 14 (0.60 g, 2.3 mmol) in THF (1.6 mL) was added to a mixture of 60%
NaH (0.11 g, 2.8 mmol) cooled in water-ice bath. The mixture was then stirred for 1 hour at room
temperature and 6 hours under reflux before extraction with dichloromethane (3 x 2 mL). The organic
4
layer was dried over MgSO , filtered and the solvent was removed on a rotavapor. The product was
purified by silica gel column chromatography using hexane-ethyl acetate (2:1) as eluent: 76% yield.
1
H-NMR (CDCl
3
) δ (ppm): 1.69 (ddd, J = 5.0/1.5/0.7 Hz, 1H), 1.73 (d, J = 11.3 Hz, 1H), 1.79 (d, J =
1
1.3 Hz, 1H), 2.03 (m, 1H), 2.30-2.44 (m, 5H), 2.51 (t, J = 2.8 Hz, 1H), 4.35 (m, 1H), 4.55 (dd, J =