1626 J ournal of Natural Products, 2003, Vol. 66, No. 12
Notes
in dichloromethane (3 mL) containing both 4 Å molecular
sieves (0.200 g) and N-methylmorpholine N-oxide (63.27 mg,
0.54 mmol). After stirring the mixture for 10 min, tetra-n-
propylammonium perruthenate (6.3 mg, 0.018 mmol) was
added and the reaction was followed by TLC until complete.
The reaction mixture was filtered through silica gel and eluted
lit.3 [R]D +22.3 (c 0.44, CHCl3); IR (neat) νmax 2927, 1603, 1470,
1218, 1050, 759 cm-1; 1H NMR (CDCl3, 300 MHz) δ 0.82, 0.83,
0.87 (3H each, s, CH3), 4.52 (1H, bs, H-17), 4.74 (1H, bs, H-17),
5.96 (1H, dd, J ) 15.9, 9.9 Hz, H-11), 6.18 (1H, d, J ) 15.9,
H-12), 6.53 (1H, bs, H-14), 7.34 (2H, bs, H-15, H-16); 13C NMR
(CDCl3, 75.45 MHz) δ 14.99 (C-20), 19.09 (C-2), 21.94 (C-19),
23.35 (C-6), 33.54 (C-4), 33.54 (C-18), 36.74 (C-7), 39.13 (C-
10), 40.74 (C-1), 42.27 (C-3), 54.77 (C-5), 61.44 (C-9), 107.61
(C-14), 107.94 (C-17), 121.71 (C-11), 124.47 (C-13), 128.26 (C-
12), 139.59 (C-15), 143.25 (C-16), 150.22 (C-8); GC/MS m/z 284
(M+, 100), 269 (9), 241 (3), 199 (5), 147 (36), 137 (9), 105 (6),
95 (14), 81 (7); HRMS m/z 284.2146 (calcd for C20H28O,
284.2157).
with hexane, affording aldehyde 8 (70 mg, 83%) as a oil; [R]24
D
+25 (c 1.5, CHCl3), lit.10 [R]D +24 (c 1.9, CHCl3); IR (neat) νmax
1724, 1641, 880 cm-1; 1H NMR (CDCl3, 300 MHz) δ 0.67, 0.78,
0.86 (3H each, s, CH3), 4.35 (1H, bs, H-13), 4.78 (1H, bs, H-13),
9.60 (1H, m, H-12); 13C NMR (CDCl3, 75.45 MHz) δ 14.53,
19.16, 21.66, 23.83, 33.48, 33.48, 37.42, 38.84, 39.29, 39.77,
41.93, 50.89, 55.16, 107.96, 148.47, 203.50; GC/MS m/z 234
(M+, 15), 217 (77), 190 (100), 137 (96), 95 (64), 81 (53); HRMS
m/z 234.1985 (calcd for C16H26O, 234.2010).
Deoxygen a tion of F u r a n ola bd a n e Alcoh ols 9 w ith Li/
NH3/NH4Cl. A stirred mixture of Li (44 mg, 15 equiv) in NH3
(15 mL) and THF (5 mL) at -78 °C was added (5 min) to a
solution of furanolabdane alcohols 9 (68 mg, 0.22 mmol) in
THF (2 mL) during 5 min. After stirring for an additional 20
min at -78 °C, NH4Cl (0.4 g) was cautiously added to
discharge the blue color, and the NH3 was allowed to evapo-
rate. After brine was added, the product was extracted with
ether. The solvent was evaporated under reduced pressure,
and the product was chromatographed over silica gel and
eluted with 5% ether in hexane to afford compound 2 (54 mg,
Oxid a tion of Alcoh ol 7 w ith P yr id in iu m Ch lor och r o-
m a te. Alcohol 7 (0.108 g, 0.45 mmol) was dissolved in
dichloromethane (3 mL) and oxidized with pyridinium chlo-
rochromate (0.197 g, 0.91 mmol) at room temperature for 30
min. The reaction mixture was filtered through silica gel, and
the filtrate was evaporated. The resulting crude product was
chromatographed over silica gel, and elution with 1% diethyl
ether in hexane afforded aldehyde 8 (86 mg, 80%) as an oil.
Cou p lin g of Ald eh yd e 8 w ith 3-F u r yllith iu m . To a
cooled solution of the 3-bromofuran (0.163 g, 0. mmol) in dry
THF (3 mL) at -78 °C was added n-butyllithium (0.6 mL, 1.6
M in hexane). The resulting brown solution was stirred for 10
min at -78 °C, and then a solution of aldehyde 8 (0.121 g,
0.51 mmol) in THF (2 mL) was added dropwise. After this
mixture had been stirred for 2 h at -78 °C, excess H2O was
added at room temperature with additional stirring for 30 min.
The product was extracted with ether and dried, and the
solvent was evaporated under reduced pressure. The product
was chromatographed over silica gel, and elution with 40%
ether in hexane afforded isomeric furanolabdane alcohols 9a
(61.3 mg, 39.2%) and 9b (68.3 mg, 43.7%).
84%) as a colorless oil; [R]24 +23 (c 2.0, CHCl3), lit.5 [R]D -22
D
(c 0.14, CHCl3); IR (neat) νmax 3050, 1635, 1495, 870 cm-1; 1H
NMR (CDCl3, 300 MHz) δ 0.67, 0.78, 0.85 (3H, s, CH3), 2.23
(1H, m, H-12), 2.39 (1H, m, H-7), 2.54 (1H, m, H-17), 4.55 (1H,
bs, H-17), 4.84 (1H, bs, H-17), 6.25 (1H, bs, H-14), 7.18 (1H,
bs, H-16), 7.33 (1H, t, H-15); 13C NMR (CDCl3, 75.45 MHz) δ
14.47 (C-20), 19.36 (C-11), 21.70 (C-19), 23.59 (C-12), 24.05
(C-2), 24.42 (C-6), 33.55 (C-4), 33.55 (C-18), 38.30 (C-7), 38.98
(C-1), 39.56 (C-10), 42.10 (C-3), 55.42 (C-5), 56.05 (C-9), 106.23
(C-17), 110.94 (C-14), 125.59 (C-13), 138.62 (C-16), 142.58 (C-
15), 148.51 (C-8); GC/MS m/z 286 (M+, 31), 271 (9), 253 (3),
191 (27), 135 (26), 95 (100), 67 (18), 41 (13); HRMS m/z
286.2290 (calcd for C20H30O, 286.2299).
F u r a n ola bd a n e a lcoh ol 9a : colorless oil; [R]24D +19 (c 1.0,
CHCl3), lit.7a [R]D +18.54 (c 0.47, CHCl3); IR (neat) νmax 3400,
2935, 2368, 1630, 1469, 880 cm-1; 1H NMR (CDCl3, 300 MHz)
δ 0.64, 0.77, 0.84 (3H each, s, CH3), 4.64 (1H, dd, J ) 8.8, 2.4
Hz, H-12), 4.48 (1H, s, H-17), 4.83 (1H, s, H-17), 6.38 (1H, bs,
H-14), 7.34, 7.35 (1H each, s, H-15, H-16); 13C NMR (CDCl3,
75.45 MHz) δ 14.39 (C-20), 19.30 (C-2), 21.64 (C-19), 24.31 (C-
6), 31.73 (C-11), 33.52 (C-4), 33.52 (C-18), 38.26 (C-7), 38.97
(C-1), 39.65 (C-10), 42.06 (C-3), 53.80 (C-9), 55.54 (C-5), 65.14
(C-12), 106.88 (C-14), 108.48 (C-17), 130.23 (C-13), 138.36 (C-
15), 143.19 (C-16), 149.70 (C-8); GC/MS m/z 302 (M+, 19), 284
(44), 191 (69), 177 (68), 137 (86), 97 (87), 95 (100), 69 (84), 41
(54); HRMS m/z 302.2248 (calcd for C20H30O2, 302.2291).
F u r a n ola bd a n e a lcoh ol 9b: colorless oil; [R]24D +13 (c 1.2,
CHCl3), lit.7a [R]D +12.73 (c 1.5, CHCl3); IR (neat) νmax 3388,
2936, 1650, 1126, 889 cm-1; 1H NMR (CDCl3, 300 MHz) δ 0.65,
0.74, 0.79 (3H each, s, CH3), 4.64 (1H, dd, J ) 9.6, 5.1 Hz,
H-12), 4.67 (1H, bs, H-17), 4.84 (1H, bs, H-17), 6.36 (1H, bs,
H-14), 7.27 (1H, bs, H-16), 7.34 (1H, t, H-15); 13C NMR (CDCl3,
75.45 MHz) δ 14.50 (C-20), 19.20 (C-2), 21.59 (C-19), 24.19 (C-
6), 31.73 (C-11), 33.40 (C-4), 33.40 (C-18), 38.08 (C-7), 38.62
(C-1), 39.35 (C-10), 41.85 (C-3), 52.70 (C-9), 55.16 (C-5), 65.76
(C-12), 106.55 (C-14), 108.16 (C-17), 128.63 (C-13), 139.58 (C-
15), 143.28 (C-16), and 148.71 (C-8); GC/MS m/z 302 (M+, 29),
284 (77), 191 (58), 177 (53), 137 (80), 97 (100), 69 (85), 41 (50);
HRMS m/z 302.2250 (calcd for C20H30O2, 302.2291).
Deyd r a t a t ion of Ma n ool (4) w it h p -Tolu en esu lfon ic
Acid . To a solution of manool (4) (3.29 g, 11.3 mmol) in dry
THF (25 mL) was added p-toluenesulfonic acid (5.83 g, 33.89
mmol) at room temperature. This mixture was refluxed for 2
h, then water was added and extracted with ether. The solvent
was evaporated under reduced pressure, and the product was
chromatographed over silica gel and eluted with hexane to
afford a colorless oil (2.01 g). Further elution with 40% ether
in hexane afforded unchanged manool (4) (0.98 g). The initial
fraction (2.01 g) was rechromatographed over silica gel im-
pregnated with 20% silver nitrate. Elution with 15% ether in
hexane afforded a colorless oil (0.85 g, 40%). The NMR
spectrum indicated that it consisted of a mixture of cis/trans-
biformene.15 Elution with 20% ether in hexane gave sclarene
(10) (1.07 g, 50%) as a colorless oil; [R]24 +45 (c 1.0, CHCl3);
D
1
IR (neat) νmax 3050, 1626, 900; H NMR (CDCl3, 300 MHz) δ
0.66, 0.78, 0.86 (3H, s, CH3), 4.53 (1H, bs, H-17), 4.82 (1H, bs,
H-17), 4.96 (1H, bs, H-16), 4.97 (1H, bs, H-16), 5.02 (1H, d, J
) 10.9 Hz, H-15), 5.20 (1H, d, J ) 17.5 Hz, H-15), 6.35 (1H,
dd, J ) 17.5, 10.9, H-14); 13C NMR (CDCl3, 75.45 MHz) δ 16.15,
18.50, 22.40, 22.90, 24.60, 29.90, 33.55, 34.40, 37.60, 39.70,
39.85, 41.80, 52.35, 54.20, 95.90, 102.21, 111.55, 138.90,
144.89, 146.73; GC/MS m/z 272 (10), 257 (100), 229 (11), 175
(19), 137 (15), 123 (18), 95 (31), 81 (13); HRMS m/z 272.2581
(calcd for C20H32, 272.2508).
Deyd r a ta tion of F u r a n ola bd a n e Alcoh ols 9. 2,6-Luti-
dine (108.9 mg, 1.01 mmol) was added to a solution of 9 (61
mg, 0.2 mmol) in dry dichloromethane (3 mL) under N2
atmosphere at 0 °C with stirring for 30 min. To the stirred
reaction mixture was added benzenesulfonyl chloride (178.3
mg, 1.01 mmol), and then it was stirred at 0 °C for an
additional 30 min and then at room temperature overnight.
An excess of dichloromethane was added to the reaction
mixture, which was washed with 10% HCl solution, saturated
NaHCO3, and brine. The solvent was evaporated under
reduced pressure, and the product was chromatographed over
silica gel. Elution with 30% ether in hexane afforded coronarin
P h otooxygen a tion of Scla r en e (10). A solution of sclare-
ne (10) (0.40 g, 1.47 mmol) in CCl4/5% methanol (50 mL)
containing meso-tetraphenylporphine (3 mg) was irradiated
at 15 °C with an external 150 W halogen-tungsten lamp for
24 h, during which time oxygen was bubbled through the
reaction mixture. The solvent was evaporated under reduced
pressure, and the residue was chromatographed over silica gel
and eluted with 5% ether in hexane to afford compound 11
(0.270 g, 60%) as white crystals (hexane): mp 36-38 °C; [R]24
D
1
+36 (c 3.0, CHCl3); IR (neat) νmax 3069, 1640, 880; H NMR
(CDCl3, 300 MHz) δ 0.66, 0.77, 0.84 (3H each, s, CH3), 4.47
(4H, m, H-15 and H-16), 4.55 (1H, bs, H-17), 4.81 (1H, bs,
H-17), 5.61 (1H, m, H-14); 13C NMR (CDCl3, 75.45 MHz) δ
E (1) (41 mg, 71%) as a colorless oil; [R]24 +25 (c 1.7, CHCl3),
D