Molecules 2002, 7
525
195 (base), 177, 139, 121, 109, 97, 83, 69, 55; HRMS (CI) Found m/z 251.2373 [M+ H]+. C13H22O
requires 251.2375.
Preparation of [1ξ,6ξ,7R,10S]-10-isopropyl-3,7-dimethylbicyclo[4.4.0]dec-3-en-1-ol (3).
To a stirred solution of 4 (350 mg, 1.4 mmol) in degassed CH2Cl2 (125 mL) was added a solution of
Grubbs reagent (57.6 mg, 5 mol%) in CH2Cl2 (15 mL) under Ar at room temperature. The mixture was
stirred overnight at r.t. The septum was removed and the mixture was stirred for further 30 min. and then
the solvent was removed. The residue was directly purified by silica gel column chromatography
(hexane-EtOAc, 0-20%) to afford 3 (298 mg, 96%): FTIR: 3450-3600 cm-1; 1H-NMR (600 MHz)δ 0.86
(3H, d, J = 6.6 Hz), 0.92 (3H, d, J = 6.9 Hz), 0.94 (3H, d, J = 6.9 Hz), 1.02 (2H, m), 1.08 (1H, m), 1.38
(1H, m), 1.50 (2H, m), 1.67 (3H, s), 1.71 (1H, m), 1.73 (1H, m), 1.96 (1H, br d, J = 18 Hz), 2.21 (3H, m),
5.44 (1H, br s); 13C-NMR (50 MHz) δ 18.2 (CH3), 19.9 (CH3), 20.3 (CH2), 23.7 (CH3), 23.7 (CH3), 25.5
(CH), 26.9 (CH2), 33.3 (CH), 35.5 (CH2), 42.8 (CH2), 46.8 (CH), 51.9 (CH), 72.5 (C), 120.2 (CH), 130.8
(CH); MS (EI) m/z 222 [M]+ 204, 189, 179, 161 (base), 139, 119, 105, 93, 84, 69, 55; HRMS (EI) Found
m/z 222.1991 [M]+. C15H26O requires 222.1983.
Preparation of (-)-calamenene (1) and [7S,10R]-2,5-dihydrocalamenene (6).
A solution of 3 (100 mg, 0.45 mmol) in pyridine (5 mL) was treated with POCl3 (0.084 mL, 2.0 eq.) at
r.t. overnight. Water was added and the mixture was extracted with ether. The organic layer was washed
with 1M HCl and brine, dried (MgSO4) and evaporated to afford a residue which was purified by silica
gel column chromatography (hexane-EtOAc, 0-20%) to give (-)-calamenene (1) (12.0 mg, 13%) and 6
(15.4 mg, 17%). 1: [α]D -73°(c 0.88, CHCl3); FTIR: 1510-1470 cm-1; 1H-NMR (200 MHz) δ 0.72 (3H,
d, J = 7.2 Hz), 1.00 (3H, d, J = 7.2 Hz), 1.26 (3H, d, J = 7.2 Hz), 1.39 (1H, m), 1.60 (1H, m), 1.81 (1H, m),
1.95 (1H, m), 2.22 (1H, m), 2.30 (3H, s), 2.70 (2H, m), 6.94 (1H, br d, J = 8.0 Hz), 7.02 (1H, br s), 7.12
(1H, d, J = 8.0 Hz); 13C-NMR (50 MHz) Table 1); MS (EI) m/z 202 [M]+ 202, 159 (base), 144, 129, 115,
115, 105, 91; HRMS (EI) Found m/z 202.1696 [M]+. C15HS requires 202.1722. 6; 1H-NMR (200 MHz)
δ 0.91(3H, d, J = 5.9 Hz), 0.93 (3H, d, J = 5.9 Hz), 0.98 (3H, d, J = 5.9 Hz), 1.68 (3H, br s), 5.42 (1H, m).
Preparation of [1ξ,6ξ,7S,10R]-6-hydroxy-7-isopropyl-4,10-dimethylbicyclo[4.4.0]dec-3-en-2-one (8).
A solution of 3 (100 mg, 0.45 mmol) in benzene (10 mL) was treated with Celite (1.05 g), tBuOOH
(0.31 mL), and PDC (1.2 g, 1.35 mmol) at 0ûC and the mixture was stirred overnight. The temperature
was gradually raised to room temperature overnight. A solution of Na2S2O3 was added and the mixture
was filtered through Celite. The filtrate was extracted with ether and the organic layer was washed with
brine, dried (MgSO4) and evaporated to afford a residue which was purified by silica gel column
1
chromatography (hexane-EtOAc, 0-30%) to give 8 (35.4 mg, 33%); FTIR: 3400, 1660 cm-1; H-NMR
(200 MHz) δ 0.90 (3H, d, J = 6.6 Hz), 0.95 (3H, d, J = 6.6 Hz), 0.95 (1H, m), 1.08 (3H, d, J = 5.8 Hz),