December 2005
1527
(film) nmax 3389, 2925, 1729, 1458, 1396, 1346, 1266, 1226, 1194, 1158,
Isolation of 16-Hydroxycarnosol (1) S. mellifera GREENE was collected
on the hillsides of Bluebird Canyon Road, Laguna Beach, California, in Au-
gust 1988 and a voucher specimen is on file at the Museum of Systematic
Biology, University of California, Irvine. The dried, ground stems and leaves
(934 g) were extracted with distilled acetone at room temperature and the
solvent eliminated under reduced pressure at 40 °C, giving an extract (138 g)
that was subjected to flash chromatography on silica gel with mixtures of n-
hexane/ethyl acetate of increasing polarity. The fraction eluted with n-
hexane/ethyl acetate (1 : 1) contained 1. Repeated chromatography on
Sephadex LH-20 and silica gel of this fraction gave 1 (520 mg).
Treatment of 16-Hydroxycarnosol (1) with N-Bromosuccinimide To
a solution of N-bromosuccinimide (123 mg, 0.691 mmol) in dry dichloro-
methane (15 ml) was added triphenylphosphine (179.6 mg, 0.684 mmol), and
the mixture was stirred at room temperature for 5 min. Pyridine (0.04 ml,
0.496 mmol) was then added dropwise to the solution, followed by the addi-
tion of 16-hydroxycarnosol (1) (78.8 mg, 0.228 mmol). The reaction mixture
was stirred at room temperature for 10 d and then poured into a saturated
aqueous sodium bicarbonate solution. The product was extracted with ethyl
acetate, washed with water and brine, and dried over anhydrous sodium
sulfate. The crude product was chromatographed over silica gel using
dichloromethane/acetone (99 : 1) as eluent to give 12,16-epoxycarnosol40)
(2) (71.2 mg, 95.3%).
Treatment of 2 with Fremy’s Salt Method (A): Fremy’s salt (potassium
nitroso disulfonate) (155.7 mg, 0.580 mmol) was dissolved in a buffer of
NaH2PO4 (10.8 ml), pH 7, under nitrogen and in the absence of light. 12,16-
Epoxycarnosol (2) (49.7 mg, 0.152 mmol) was dissolved in acetonitrile
(10.8 ml) and added to the above solution. The mixture was stirred at room
temperature for 5.5 h and then was extracted with ethyl acetate, washed with
brine, and the organic layers dried over anhydrous Na2SO4. The solvent was
eliminated under reduced pressure, and the crude product was purified by
preparative TLC using dichloromethane/acetone (99 : 1) as eluent to yield
two products: 11,14-dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3)
(34.4 mg, 66.4%) and 11,14-dioxo-12,16-epoxy-8,12,15(16)-abietatrien-
20,7b-olide (4) (3.2 mg, 6.2%).
Method (B): To a buffer solution of NaH2PO4 (30 ml), pH 7, was added a
solution of Aliquat 336 (0.1 ml, 0.219 mmol) and 12,16-epoxycarnosol (2)
(58.4 mg, 0.178 mmol) in dichloromethane (8 ml) and Fremy’s salt (135 mg,
0.504 mmol). The reaction mixture was stirred at room temperature for 2 h
and then extracted with dichloromethane, washed with brine, and dried over
anhydrous Na2SO4. The solvent was eliminated under reduced pressure, and
the crude product was purified by silica gel columm chromatography using
dichloromethane as eluent to obtain 11,14-dioxo-12,16-epoxy-8,12-abieta-
dien-20,7b-olide (3) (55.0 mg, 90.2%).
1098, 1030, 828, 758 cmꢁ1 1H-NMR (300 MHz) d 0.87 (3H, s, Me-19),
;
0.94 (3H, s, Me-18), 2.21 (3H, s, Me-17), 2.54 (1H, td, Jꢂ4.5, 14.0 Hz, H-
1a), 2.98 (1H, br d, Jꢂ14.0 Hz, H-1b), 5.45 (1H, br s, Ar-OH), 5.52 (1H, dd,
Jꢂ1.4, 4.0 Hz, H-7), 6.97 (1H, s, H-14), 7.40 (1H, s, H-16); 13C-NMR
(75 MHz) d 18.9 (t, C-2), 19.7 (q, C-18, and C-19), 29.0 (t, C-1), 29.2 (t, C-
6), 31.7 (q, C-17), 34.6 (s, C-4), 41.1 (t, C-3), 45.8 (d, C-5), 48.7 (s, C-10),
78.0 (d, C-7), 106.0 (d, C-14), 116.8 (s, C-15), 119.6 (s, C-9), 128.3 (s, C-
13), 138.7 (s, C-11), 142.0 (d, C-16), 144.5 (s, C-12), 175.7 (s, C-20); EI-
MS m/z 326 [M]ꢀ (32), 283 (21), 282 (100), 267 (20), 225 (11), 211 (44),
199 (23), 111 (14), 97 (20), 83 (20), 71 (22), 57 (31); [a]D20 ꢁ23.1° (cꢂ0.13,
CHCl3); HR-EI-MS m/z 326.1528 (Calcd for C20H22O4, 326.1518).
Treatment of 11,14-Dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3)
with Pyridine in Benzene Pyridine (0.4 ml, 4.96 mmol) was added to
a
solution of 11,14-dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3)
(11.0 mg, 0.0322 mmol) in benzene (10 ml) and the mixture was refluxed for
48 h. Then the solvent was eliminated in vacuo, and the crude product was
purified by preparative TLC using dichloromethane/acetone (9.5 : 0.5) as
eluent to obtain three products: 11,14-dioxo-12,16-epoxy-8,12,15(16)-abi-
etatrien-20,7b-olide (4) (2.2 mg, 20.2%), isotanshinone II (6) (1.2 mg,
12.7%), and 1-oxoisotanshinone II (7) (0.7 mg, 7.1%).
Isotanshinone II (6): Obtained as an amorphous solid. mp 208 °C; UV
(EtOH) lmax (log e) 227 (4.02), 253 (4.33), 256 (4.34), 303 (3.59), 361
(3.63) nm; IR (film) nmax 3150, 1655, 1585, 1530, 1030, 840 cmꢁ1; 1H-NMR
(300 MHz) d 1.34 (6H, s, Me-18 and Me-19), 2.36 (3H, s, Me-17), 3.36
(2H, t, Jꢂ6.4 Hz, H-2), 7.46 (1H, s, H-16), 7.73 (1H, d, Jꢂ8.3 Hz, H-7),
8.06 (1H, d, Jꢂ8.3 Hz, H-6); EI-MS m/z 294 [M]ꢀ (13), 219 (19), 154 (57),
136 (51), 107 (19), 91 (63), 81 (50), 71 (36), 69 (87), 55 (100); HR-EI-MS
m/z 294.1207 (Calcd for C19H18O3, 294.1256).
1-Oxoisotanshinone II (7): Obtained as an amorphous solid. UV (EtOH)
lmax (log e) 268 (3.74), 239 (3.93) nm; IR (film) nmax 2961, 2926, 2854,
1702, 1673, 1581, 1530, 1464, 1388, 1364, 1234, 1173, 1147, 1118, 1093,
1038, 756 cmꢁ1 1H-NMR (300 MHz) d 1.25 (3H, s, Me-19), 1.36 (3H, s,
;
Me-18), 2.05 (2H, t, Jꢂ7.3 Hz, H-3), 2.37 (3H, s, Me-17), 3.00 (2H, t, Jꢂ
7.3 Hz, H-2), 7.51 (1H, s, H-16), 7.66 (1H, d, Jꢂ8.2 Hz, H-7), 8.20 (1H, d,
Jꢂ8.2 Hz, H-6); EI-MS m/z 308 [M]ꢀ (25), 293 (11), 280 (41), 265 (42),
252 (100), 165 (8), 115 (87), 55 (5); [a]D20 ꢁ10.0° (cꢂ0.05, CHCl3); HR-EI-
MS m/z 308.1070 (Calcd for C19H16O4, 308.1048).
Treatment of 11,14-Dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3)
t
with BuOK in Dimethylsulfoxide Compound 3 (4.8 mg, 0.014 mmol)
t
was dissolved in 2 ml of DMSO and then BuOK (8.5 mg, 0.076 mmol) was
added and heated at 100 °C for 48 h. Then the reaction mixture was acidified
with aqueous 5% HCl, extracted with ethyl acetate, washed with brine, and
dried over anhydrous Na2SO4. The solvent was eliminated on a rotary evapo-
rator, and the crude product was purified by preparative TLC using
dichloromethane/acetone (9.5 : 0.5) as eluent to give (ꢀ)-neocryptotanshi-
none (8) (2.1 mg, 47.7%).
11,14-Dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3): Obtained as
an amorphous solid. UV (EtOH) lmax (log e) 441 (2.77), 292 (3.62), 261
(3.58) nm; IR (film) nmax 2956, 1752, 1678, 1645, 1595, 1460, 1406, 1361,
1
1286, 1220, 1150, 1108, 1014, 756 cmꢁ1; H-NMR (300 MHz) d 0.86 (3H,
(ꢀ)-Neocryptotanshinone (8): Obtained as an amorphous solid. UV
(EtOH) lmax (log e) 281 (4.04), 248 (4.11) nm; IR (film) nmax 3330, 2970,
2870, 1770, 1660, 1570, 1465 cmꢁ1; 1H-NMR (300 MHz) d 1.23 (3H, d, Jꢂ
7 Hz, Me-17), 1.27 (6H, s, Me-18 and Me-19), 3.20 (2H, t, Jꢂ6.0 Hz, H-1),
3.42 (1H, m, H-15), 3.84 (1H, dd, Jꢂ5.0, 11.0 Hz, H-16), 3.94 (1H, dd, Jꢂ
8.0, 11.0 Hz, H-16ꢃ), 7.70 (1H, d, Jꢂ8.0 Hz, H-7), 7.95 (1H, d, Jꢂ8.0 Hz, H-
6); EI-MS m/z 314 [M]ꢀ (26), 296 (20), 284 (29), 182 (19), 151 (11), 137
(14), 125 (22), 111 (36), 99 (20), 95 (36), 69 (60), 57 (100); [a]D20 ꢀ29.2°
(cꢂ0.73, CHCl3); HR-EI-MS m/z 314.1518 (Calcd for C19H22O4, 314.1518).
Treatment of 11,14-Dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide (3)
with KOH in THF 11,14-Dioxo-12,16-epoxy-8,12-abietadien-20,7b-olide
(3) (53.4 mg, 0.157 mmol) was dissolved with THF (3 ml) and was cooled at
0 °C. Then an aqueous solution of 1% KOH (3 ml) was added and after
30 min the reaction mixture was acidified with 5% HCl, extracted with ethyl
acetate, washed with brine, and dried over anhydrous Na2SO4. The crude re-
action was purified by silica gel columm chromatography eluting with
dichloromethane yielding 16-hydroxycolumbaridione (9) (52.8 mg, 94%).
16-Hydroxycolumbaridione (9): Obtained as an amorphous solid. UV
(EtOH) lmax (log e) 286 (4.16), 231 (4.20) nm; IR (film) nmax 3352, 2953,
1748, 1635, 1459, 1399, 1321, 1290, 1158, 1109, 1029, 996, 971, 908, 882,
753, 668 cmꢁ1; 1H-NMR (300 MHz) d 0.88 (3H, s, Me-19), 0.90 (3H, s, Me-
18), 1.21 (3H, d, Jꢂ7.0 Hz, Me-17), 2.72 (1H, br d, Jꢂ14.5 Hz, H-1b), 3.30
(1H, sext, Jꢂ6.8 Hz, H-15), 3.83 (2H, m, H-16), 5.80 (1H, dd, Jꢂ1.4,
4.0 Hz, H-7); EI-MS m/z 362 [Mꢀ2]ꢀ (44), 344 (47), 316 (68), 314 (75),
298 (100), 296 (72), 284 (91), 281 (37), 270 (32), 228 (29), 215 (32), 128
(30), 69 (25); [a]D20 ꢁ4.81° (cꢂ0.13, CHCl3); HR-EI-MS m/z 362.1766
s, Me-19), 0.89 (3H, s, Me-18), 1.32 (3H, d, Jꢂ6.8 Hz, Me-17), 2.71 (1H,
br d, Jꢂ14.3 Hz, H-1b), 3.56 (1H, sext, Jꢂ3.4 Hz, H-15), 4.26 (1H, dd, Jꢂ
2.9, 6.6 Hz, H-16), 4.77 (1H, t, Jꢂ9.9 Hz, H-16ꢃ), 5.76 (1H, dd, Jꢂ1.4,
4.0 Hz, H-7); 13C-NMR (75 MHz) d 18.2 (t, C-2), 18.7 (q, C-17), 19.5 (q, C-
18), 27.0 (t, C-1), 27.7 (t, C-6), 32.2 (q, C-19), 34.6 (s, C-4), 35.2 (d, C-15),
40.5 (t, C-3), 44.8 (d, C-5), 49.2 (s, C-10), 69.6 (d, C-7), 80.6 (t, C-16),
123.1 (s, C-13), 140.4 (s, C-8), 146.2 (s, C-9), 158.7 (s, C-12), 173.5 (s, C-
20), 176.6 (s, C-11), 179.2 (s, C-14); EI-MS m/z 342 (7), 300 (24), 298 (21),
219 (14), 154 (53), 136 (48), 109 (21), 95 (37), 81 (49), 69 (79), 55 (100);
HR-EI-MS m/z 342.1439 (Calcd for C20H22O5, 342.1467).
11,14-Dioxo-12,16-epoxy-8,12,15(16)-abietatrien-20,7b-olide (4): Ob-
tained as an amorphous solid. UV (EtOH) lmax (log e) 251 (4.63) nm; IR
(film) nmax 2924, 2854, 1754, 1667, 1587, 1528, 1463, 1360, 1290, 1238,
1147, 1109, 1030, 1003, 906, 760, 669 cmꢁ1 1H-NMR (300 MHz) d 0.90
;
(6H, s, Me-18 and Me-19), 2.27 (3H, s, Me-17), 2.46 (1H, td, Jꢂ4.3,
14.0 Hz, H-1a), 2.80 (1H, br d, Jꢂ14.0 Hz, H-1b), 5.85 (1H, dd, Jꢂ1.4,
4.0 Hz, H-7), 7.45 (1H, s, H-16); [a]D20 ꢁ3.13° (cꢂ0.08, CHCl3). Anal.
Calcd for C20H20O5: C, 70.57; H, 5.92. Found: C, 70.41; H, 6.10.
Treatment of 12,16-Epoxycarnosol (2) with DDQ 12,16-Epoxy-
carnosol (2) (44.7 mg, 0.136 mmol) was dissolved in dry benzene (5 ml) and
then added to a solution of DDQ (62.3 mg, 0.274 mmol) in dry benzene
(5 ml). The reaction mixture was stirred at room temperature for 3 d and then
was filtered through silica gel using n-hexane/acetone (1 : 1) as solvent to
obtain 5 (7.0 mg, 15.8%).
15,16-Didehydro-12,16-epoxycarnosol (5): Obtained as an amorphous
solid. UV (EtOH) lmax (log e) 283 (4.30), 262 (4.46), 232 (4.45) nm; IR