Pu Zhang et al. / Tetrahedron 65 (2009) 4304–4309
4307
was stirred for 10 min. At this point, the mixture was neutralized
with NaHCO3 saturated solution, and then extracted with CH2Cl2,
the CH2Cl2 layer was washed with brine, dried over anhydrous
Na2SO4, filtered, and evaporated to dryness. The residue was pu-
rified by flash chromatography (SiO2, dichloromethane/ethyl ace-
tate, 15:1) to give 13 as a white amorphous solid (17.6 mg, 97%). Mp
was purified by flash chromatography (SiO2, petroleum ether/ethyl
acetate, 11:1) to give 16 as a white amorphous solid (0.94 g, 99%).
Mp 191–194 ꢀC. [
a
]
D þ27.5 (c 0.235, CH2Cl2). IR (film, cmꢁ1): 3457,
2947, 2865, 1703, 1460, 1458, 1385, 1375, 1257, 1016, 849, 738, 595;
1H NMR (CDCl3)
d 0.79 (3H, s), 0.96 (6H, s), 0.99 (3H, s), 1.01 (3H, s),
1.06 (3H, s), 1.08 (3H, s), 1.10–1.96 (20H, m), 2.21 (1H, d, J¼1.6 Hz),
278–280 ꢀC. [
a
]
D
þ40 (c 0.09, CH2Cl2). IR (film, cmꢁ1): 3139, 2945,
2.44–2.51 (2H, m), 3.47 (1H, d, J¼10.8 Hz), 3.64 (1H, d, J¼10.7 Hz),
2871, 2686, 2272, 1706, 1509, 1461, 1385, 1087, 1034, 729, 509; 1H
5.17 (1H, s); 13C NMR (CDCl3)
d 14.6, 16.0, 16.5, 19.7, 20.9, 21.6, 26.2,
NMR (CDCl3)
d
0.93 (3H, s), 0.96 (6H, s), 0.97 (3H, s),1.04 (3H, s),1.08
26.9, 27.3, 29.8, 30.5, 31.2, 31.7, 32.2, 33.3, 33.9, 34.0, 36.9, 38.8, 39.6,
39.9, 40.8, 43.2, 47.3, 50.5, 54.9, 65.6, 134.6; ESI MS m/z 463.3
[MþNa]þ; HRMS for C30H48O2 calcd 440.3654, found 440.3656.
(3H, s), 1.09 (3H, s), 1.18–2.04 (22H, m), 2.42–2.55 (2H, m), 3.33 (1H,
s), 3.48 (1H, d, J¼11.6 Hz), 4.15 (1H, d, J¼11.5 Hz); 13C NMR (CDCl3)
d
14.6, 15.7, 15.9, 19.7, 21.1, 21.4, 24.5, 25.8, 26.6, 26.7, 28.0, 30.7, 32.7,
33.3, 33.4, 34.1, 34.4, 35.3, 36.9, 37.8, 39.6, 41.1, 42.0, 42.4, 47.4, 49.5,
55.1, 64.6, 74.7, 217.9; ESI MS m/z 481.3 [MþNa]þ; HRMS for
C30H50O3 calcd 458.3760, found 458.3772.
4.9. Moronic aldehyde (7)
To a solution of 16 (600 mg, 1.36 mmol) in CH2Cl2 (60 mL) was
added PCC (590 mg, 2.73 mmol). The reaction mixture was allowed
to stir at room temperature for 1 h. At this point, the residue was
removed by filtration and the solvent was evaporated under
reduced pressure to give crude moronic aldehyde 7. The residue
was purified by flash chromatography (SiO2, petroleum ether/ethyl
acetate, 19:1) to give 7 as a white amorphous solid (525 mg, 88%).
4.6. 28-Acetate-3-oxooleanane-19,28-diol (14)
To a solution of 13 (100 mg, 0.217 mmol) in pyridine (2.5 mL)
was added Ac2O (0.04 mL, 0.435 mmol). The reaction mixture was
stirred at room temperature for 4 h. At this point, the mixture was
neutralized with 3 N HCl, and then extracted with EtOAc, the EtOAc
layer was washed with brine, dried over anhydrous Na2SO4, fil-
tered, and evaporated to dryness. The residue was purified by flash
chromatography (SiO2, petroleum ether/ethyl acetate, 15:1) to give
Mp 222–224 ꢀC [lit.,5 mp 145–148 ꢀC]. [
a
]
D
þ71 (c 0.195, CHCl3)
[lit.,5
[a
]
þ46 (c 0.5, CHCl3)]. IR (KBr, cmꢁ1): 2954, 2863, 2676,
D
2363, 1717, 1704, 1456, 1384, 1377, 1275, 1115, 976, 845, 585; 1H
NMR (CDCl3)
(3H, s), 0.85–2.09 (21H, m), 2.43–2.49 (2H, m), 5.30 (1H, s), 9.38
(1H, s); 13C NMR (CDCl3)
14.7, 15.9, 16.5, 19.6, 21.0, 21.4, 26.5, 26.9,
d 0.79 (3H, s), 0.95 (3H, s), 0.99 (9H, s),1.02 (3H, s),1.07
14 as a white amorphous solid (101 mg, 93%). Mp 204–206 ꢀC. [
a]
D
þ39.9 (c 0.18, CH2Cl2). IR (film, cmꢁ1): 3537, 2944, 2867, 1730, 1705,
d
1460, 1386, 1364, 1242, 1114, 1032, 970, 738, 704; 1H NMR (CDCl3)
28.8, 29.1, 29.4, 29.5, 30.6, 32.2, 33.1, 33.9, 34.1, 36.9, 39.9, 40.6, 41.3,
42.7, 47.3, 49.9, 51.5, 55.1,134.7,135.4, 204.9, 217.9; ESI MS m/z 439.2
[MþH]þ; HRMS for C30H46O2 calcd 438.3498, found 438.3502.
d
0.91 (3H, s), 0.95 (6H, s), 0.96 (3H, s), 1.03 (3H, s), 1.08 (3H, s), 1.10
(3H, s), 0.79–1.96 (22H, m), 2.04 (3H, s), 2.35–2.55 (2H, m), 3.32
(1H, s), 4.30 (1H, d, J¼11.9 Hz), 4.625 (1H, d, J¼11.8 Hz); 13C NMR
(CDCl3)
d
14.7, 15.8, 15.9, 19.7, 21.1, 21.4, 24.6, 25.7, 26.5, 26.6, 27.8,
4.10. Moronic acid (2)
29.5, 31.4, 31.6, 32.8, 33.3, 34.2, 35.3, 36.9, 37.1, 39.7, 41.1, 42.2, 42.6,
47.4, 49.6, 55.2, 62.6, 74.7, 171.3, 217.9; HRMS for C32H52O4 calcd
500.3866, found 500.3864.
To a solution of 7 (400 mg, 0.91 mmol) in t-BuOH (26 mL) and
THF (5 mL) was added 2-mythyl-2-butene (8 mL). The mixture was
allowed to stir in an ice bath. NaClO2 and NaH2PO4 were dissolved
into water, the solution was added to the mixture. The mixture was
allowed to stir in an ice bath for 15 min, and then stirred at room
temperature for 12 h. At this point, NH4Cl was added, the mixture
was extracted with EtOAc, the organic layer was washed with brine,
dried over anhydrous Na2SO4, filtered, and evaporated to dryness.
The residue was purified by flash chromatography (SiO2, petroleum
ether/ethyl acetate, 14:1) to give 2 as a white amorphous solid
4.7. 28-Acetate-3-oxooleanane-18-en-28-ol (15)
To a solution of 14 (600 mg, 1.20 mmol) in pyridine (20 mL) was
added POCl3 (2.8 mL, 7.2 mmol). The reaction mixture was allowed
to reflux for 1.5 h. At this point, the pyridine was removed, then
dimethylacetamide (20 mL) was added, then the solution was
refluxed for 0.5 h. At this point, the solution was added to 8 mL H2O,
and extracted with AcOEt, the AcOEt layer was washed with brine,
dried over anhydrous Na2SO4, filtered, and evaporated to dryness.
The residue was purified by flash chromatography (SiO2, petroleum
ether/ethyl acetate, 30:1) to give 15 as a colorless oily product
(350 mg, 85%). Mp 172–175 ꢀC [lit.,7 mp 210–212 ꢀC]. [
a
]
þ61 (c
0.12, CHCl3) [lit.,4 [
a
]
D þ59.3 (c 1.01, CHCl3)]. IR (film, cmꢁD1): 3402,
2950, 2865, 2612, 1697, 1452, 1385, 1376, 1265, 1143, 1108, 1019, 951,
845, 738, 578; 1H NMR (CDCl3)
s), 1.13 (3H, s), 1.14 (3H, s), 1.15 (3H, s), 1.20 (3H, s), 0.96–2.39 (21H,
m), 2.57–2.64 (2H, m), 5.30 (1H, s); 13C NMR (CDCl3)
14.8, 15.8,
d 0.92 (3H, s), 1.07 (3H, s), 1.10 (3H,
(390 mg, 67%). Mp 90–92 ꢀC. [
cmꢁ1): 3393, 2945, 2865, 2676, 2287, 1738, 1706, 1453, 1383, 1365,
1232, 1107, 1033, 737; 1H NMR (CDCl3)
0.77 (3H, s), 0.95 (3H, s),
a
]
þ33.1 (c 0.07, CH2Cl2). IR (film,
D
d
d
16.5, 19.6, 20.9, 21.5, 26.0, 26.8, 29.1, 29.4, 30.3, 32.1, 33.3, 33.47,
33.53, 33.8, 34.0, 36.9, 39.8, 40.6, 41.5, 42.6, 47.3, 48.0, 50.5, 54.9,
133.4, 136.6, 181.2, 218.1; ESI MS m/z 453.3 [MꢁH]ꢁ; HRMS for
C30H46O3 calcd 454.3447, found 454.3448.
0.96 (6H, s), 1.03 (3H, s), 1.07 (3H, s), 1.09 (3H, s), 1.17–1.96 (20H, m),
2.06 (3H, s), 2.20–2.48 (3H, m), 3.99 (1H, d, J¼11.1 Hz), 4.14 (1H, d,
J¼11.1 Hz), 5.06 (1H, s); 13C NMR (CDCl3)
d 14.6, 16.0, 16.5, 19.6, 20.9,
21.0, 21.6, 26.2, 26.8, 27.3, 29.4, 30.8, 31.30, 31.34, 32.2, 32.8, 33.8,
34.0, 36.9, 37.7, 39.0, 39.8, 40.7, 43.1, 47.2, 49.8, 50.5, 54.9, 65.8,
133.7, 138.0, 171.2; EIMS m/z 482 (12), 203 (100); HRMS for
C32H50O3 calcd 482.3760, found 482.3768.
4.11. Morolic acid (1)
To a solution of 2 (60 mg, 0.13 mmol) in THF (2 mL) and EtOH
(0.5 mL) was added NaBH4 (10 mg, 0.26 mmol). The reaction mix-
ture was allowed to stir at room temperature for 3 h. At this point,
the mixture was neutralized with 1 N HCl and extracted with
EtOAc, the EtOAc layer was washed with brine, dried over anhy-
drous Na2SO4, filtered, and evaporated to dryness. The residue was
purified by flash chromatography (SiO2, petroleum ether/ethyl
acetate,14:1) to give 1 as a white amorphous solid (50 mg, 85%). Mp
4.8. 3-Oxooleanane-18-en-28-ol (16)
To a solution of 15 (1.05 g, 2.178 mmol) in THF (10 mL) was
added KOH/MeOH (11.1 g/162 mL). The reaction mixture was
allowed to stir at room temperature for 6 h. At this point, the re-
action mixture was neutralized with 3 N HCl, and then extracted
with AcOEt, the AcOEt layer was washed with brine, dried over
anhydrous Na2SO4, filtered, and evaporated to dryness. The residue
269–271 ꢀC [lit.,30 mp 273 ꢀC]. [
a]
þ31 (c 0.085, CHCl3) [lit.,4
[a]
D
D
þ39.8 (c 0.13, CHCl3)]. IR (film, cmꢁ1): 3473, 2929, 2863, 2299,1695,