Partial synthesis of krukovines A and B, triterpene ketones isolated from the Brazilian medicinal plant Maytenus krukovii

Article abstract of DOI:10.1021/np9702897

Krukovines A (1) and B (2), triterpene ketones isolated from the Brazilian medicinal plant 'chuchuhuasi' (Maytenus krukovii), were synthesized in eight steps from the commercially available oleanolic acid and ursolic acid, respectively.

Full text of DOI:10.1021/np9702897

1174
J . Nat. Prod. 1997, 60, 1174-1177
P a r tia l Syn th esis of Kr u k ovin es A a n d B, Tr iter p en e Keton es Isola ted fr om th e
Br a zilia n Med icin a l P la n t Ma yten u s kr u kovii
Tadashi Honda, Heather J . Finlay, and Gordon W. Gribble*
Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755
Received J une 12, 1997X
Krukovines A (1) and B (2), triterpene ketones isolated from the Brazilian medicinal plant
“chuchuhuasi” (Maytenus krukovii), were synthesized in eight steps from the commercially
available oleanolic acid and ursolic acid, respectively.
Many oleanane and ursane triterpenoids are reported
to have interesting biological, pharmacological, and
medicinal activities similar to those of retinoids and
steroids. These include antiinflammatory activity, sup-
pression of tumor promotion, suppression of immuno-
globulin synthesis, protection of the liver against toxic
injury, induction of collagen synthesis, and induction
of differentiation in leukemia or teratocarcinoma cells.1
Therefore, it is important to supply those triterpenoids
with novel structures in sufficient amounts for biological
testing. And, in this regard, synthesis rather than
isolation from natural sources is more efficient and
economical.
Recently, the new triterpene ketones krukovines A
and B were isolated from the Brazilian medicinal plant
Maytenus krukovii A. C. Smith (Celastraceae) (local
name “chuchuhuasi”), which is used for the treatment
of skin cancer. These interesting compounds were
determined to be 1 and 2 based on spectral data.2 In
this paper, we wish to describe the first synthesis of
krukovines A and B from the commercially available
oleanolic acid and ursolic acid, respectively. Our work
confirms the structures proposed for these compounds.
tetra-n-butylammonium fluoride3 did not give a good
result, desilylation of 7 with hydrofluoric acid in MeCN5
gave hydroxy acetate 8 in 91% yield. J ones’ oxidation
of 8 gave keto acetate 9 in 98% yield. Allyllic oxidation6
of 9 gave the R,â-unsaturated ketone 10 in 41% yield.
Alkaline hydrolysis of 10 with KOH in MeOH (at room
temperature, 30 min) gave krukovine A (1) in quantita-
tive yield. Interestingly, reflux conditions gave 1 in only
52% yield because of decomposition of 10. Similarly,
krukovine B (2) was synthesized from ursolic acid (11)
according to the same method. The yields of each step
are described in the Experimental Section. 1H- and 13C-
NMR spectra of our synthetic krukovines A and B were
identical with those of authentic krukovines A and B,
respectively. Our synthesis not only confirms the
structures proposed for krukovines A and B, but also
provides sufficient material for biological testing.
Exp er im en ta l Section
Gen er al Exper im en tal P r ocedu r es. Melting points
were determined on a Thomas Hoover capillary melting
point apparatus and are uncorrected. Optical rotations
were measured with a J ASCO DIP-181 digital polarim-
eter, and [R]D values are given in 10-1 deg cm2 g-1. UV
and IR spectra were recorded on a Perkin-Elmer Lambda
9 UV/vis/NIR spectrophotometer and a Perkin-Elmer
600 series FTIR spectrophotometer, respectively. 1H-
(300 MHz) and 13C- (75 MHz) NMR spectra were
recorded on a Varian XL-300 Fourier transform spec-
trometer. The chemical shifts are reported in δ (ppm)
using the δ 7.27 signal of CHCl3 (1H NMR) and δ 77.30
signal of CDCl3 (13C NMR) as an internal standard.
LRMS and HRMS were obtained on a VG Analytical
ZAB 2SE high-field mass spectrometer. The standard
workup method was as follows: an organic extract was
washed with saturated aqueous NaHCO3 solution (three
times) and then with saturated aqueous NaCl solution
(three times), dried over anhydrous MgSO4, and filtered.
Krukovines A and B have a hydroxymethyl group at
C-17 and two carbonyl groups at C-3 and C-11. On the
other hand, oleanolic acid and ursolic acid (starting
materials) have a carboxyl group at C-17 and a hydroxyl
group at C-3. Therefore, the order of protection, depro-
tection, reduction, and oxidation is very important.
Consequently, we adopted the route as shown in Scheme
1.
Methyl 3-[(tert-butyldimethylsilyl)oxy]olean-12-en-28-
oate (5) was prepared in 98% yield with tert-butylchlo-
rodimethylsilane and imidazole in DMF3 from methyl
oleanolate (4) derived from oleanolic acid (3) as re-
ported.4 LiAlH4 reduction of 5 gave alcohol 6 in 90%
yield. Acetylation of 6 with Ac2O in pyridine gave
acetate 7 in 94% yield. Although desilylation of 7 with
Meth yl 3-[(ter t-Bu tyld im eth ylsilyl)oxy]olea n -12-
en -28-oa te (5). To a stirred solution of methyl oleano-
late (4) (600 mg, 1.3 mmol) in anhydrous DMF (3 mL)
were added tert-butylchlorodimethylsilane (378 mg, 2.5
mmol) and imidazole (342 mg, 5.0 mmol). The mixture
was stirred at room temperature overnight. It was
diluted with a mixture of CH2Cl2 and Et2O (1:2). After
the mixture was washed with 5% aqueous HCl (three
times), it was worked up according to the standard
method. The filtrate was evaporated in vacuo to give a
residue (839 mg). The residue was subjected to flash
column chromatography on Si gel [hexane-EtOAc (7:
* To whom correspondence should be addressed. Phone: 603-646-
3118. FAX: 603-646-3946. E-mail: grib@dartmouth.edu.
X Abstract published in Advance ACS Abstracts, October 15, 1997.
S0163-3864(97)00289-9 CCC: $14.00
© 1997 American Chemical Society and American Society of Pharmacognosy

Notes
J ournal of Natural Products, 1997, Vol. 60, No. 11 1175
Sch em e 1a
a
Key: (a) CH2N2/Et2O/THF; (b) TBDMSCl/imid/DMF; (c) LAH/THF; (d) Ac2O/pyr; (e) 48% HF/CH3CN (1:9); (f) J ones; (g) CrO3/pyr/
CH2Cl2; (h) KOH/MeOH.
1)] to give the title compound as an amorphous solid
(728 mg, yield: 98%): IR (KBr) νmax 2949, 1727, 1472,
1386, 1361, 1254, 1201, 1163, 1099, 1073, 1033, 1004
cm-1; 1H NMR (CDCl3, 300 MHz) δ 5.29 (1H, t, J ) 3.4
Hz, H-12), 3.63 (3H, s, CO2CH3), 3.19 (1H, dd, J ) 11.0,
4.8 Hz, H-3), 1.13, 0.93 (each 3H, s, t-CH3), 0.91 (6H, s,
t-CH3 × 2), 0.89 [9H, s, SiC(CH3)3], 0.87, 0.75, 0.72 (each
3H, s, t-CH3), 0.039 [6H, s, Si(CH3)2]; FABMS (NBA)
m/ z 585 [M + H]+ (38), 583 (47), 527 (45), 453 (100),
393 (33); HRFABMS m/ z 585.4706 [M + H]+ (calcd for
C37H64O3Si + H, 585.4703).
Met h yl 3-[(ter t-Bu t yld im et h ylsilyl)oxy]u r s-12-
en -28-oa te (13). The title compound was prepared
from methyl ursolate (12)7 (100 mg, 0.21 mmol) accord-
ing to the same method as for 5 to give an amorphous
solid (102 mg, yield: 83%): IR (KBr) νmax 2950, 1727,
1461, 1388, 1359, 1254, 1199, 1142, 1098, 1076, 1004
cm-1; 1H NMR (CDCl3, 300 MHz) δ 5.25 (1H, t, J ) 3.5
Hz, H-12), 3.61 (3H, s, CO2CH3), 3.19 (1H, dd, J ) 11.4,
4.8 Hz, H-3), 2.23 (1H, d, J ) 11.0 Hz, H-18), 1.08 (3H,
s, t-CH3), 0.96 (3H, br s, H3-30), 0.92, 0.91 (each 3H, s,
t-CH3), 0.89 [9H, s, SiC(CH3)3], 0.86 (3H, d, J ) 6.0 Hz,
H3-29), 0.75, 0.74 (each 3H, s, t-CH3), 0.037 [6H, s, Si-
(CH3)2]; CIMS (NH3) m/ z 603 [M + NH4]+ , 586 [M +
H]+.
3-[(ter t-Bu t yld im et h ylsilyl)oxy]olea n -12-en -28-
ol (6). To a stirred solution of methyl 3-[(tert-butyldi-
methylsilyl)oxy]urs-12-en-28-oate (5) (681 mg, 1.2 mmol)
in anhydrous THF (43 mL) was added LiAlH4 (390 mg,
10 mmol) under nitrogen atmosphere at room temper-
ature. The slurry was stirred at room temperature
overnight. To the mixture were added H2O (0.9 mL),
40% aqueous NaOH solution (0.3 mL), and H2O (0.9
mL), successively. After an insoluble matter was re-
moved by filtration through Celite, the filtrate was
evaporated in vacuo to give a residue (723 mg). The
residue was subjected to flash column chromatography
[hexane-EtOAc (6:1)] to give the title compound as an
amorphous solid (585 mg, yield: 90%): IR (KBr) νmax
3435, 2950, 1463, 1387, 1361, 1255, 1103, 1077, 1005
cm-1; 1H NMR (CDCl3, 300 MHz) δ 5.20 (1H, t, J ) 3.5
Hz, H-12), 3.56 (1H, d, J ) 10.9 Hz, H-28a), 3.22 (1H,
d, J ) 10.9 Hz, H-28b), 3.19 (1H, dd, J ) 11.2, 4.9 Hz,
H-3), 1.17, 0.94, 0.93, 0.91 (each 3H, s, t-CH3), 0.89 [12H,
s, SiC(CH3)3 and t-CH3], 0.88, 0.76 (each 3H, s, t-CH3),
0.042 [6H, s, Si(CH3)2]; FABMS (NBA) m/ z 557 [M +
H]+ (9), 556 [M]+ (14), 499 (9), 425 (25), 203 (100);
HRFABMS m/ z 557.4772 [M + H]+ (calcd for C36H64O2-
Si + H, 557.4754).
3-[(ter t-Bu t yld im et h ylsilyl)oxy]u r s-12-en -28-ol
(14). The title compound was prepared from methyl
3-[(tert-butyldimethylsilyl)oxy]urs-12-en-28-oate (13) (88
mg, 0.15 mmol) according to the same method as for 6
to give an amorphous solid (74 mg, yield: 89%): IR
(KBr) νmax 3456, 2929, 1461, 1387, 1254, 1101, 1069,
1023, 1004 cm-1; 1H NMR (CDCl3, 300 MHz) δ 5.14 (1H,
t, J ) 3.5 Hz, H-12), 3.54 (1H, d, J ) 11.0 Hz, H-28a),
3.205 (1H, d, J ) 11.0 Hz, H-28b), 3.197 (1H, dd, J )
11.2, 4.9 Hz, H-3), 1.11, 0.99, 0.95 (each 3H, s, t-CH3),
0.94 (3H, br s, H3-30), 0.92 (3H, s, t-CH3), 0.90 [9H, s,
SiC(CH3)3], 0.81 (3H, d, J ) 5.9 Hz, H3-29), 0.76 (3H, s,
t-CH3), 0.04 [6H, s, Si(CH3)2]; CIMS (NH3) m/ z 558 [M
+ H]+.
3-[(ter t-Bu t yld im et h ylsilyl)oxy]olea n -12-en -28-
yl Aceta te (7). A mixture of 3-[(tert-butyldimethylsi-
lyl)oxy]olean-12-en-28-ol (6) (569 mg, 1.0 mmol), Ac2O
(2.8 mL), and pyridine (5.6 mL) was kept at room
temperature overnight. After MeOH was added to the
mixture to decompose the excess Ac2O in an ice bath, it
was evaporated in vacuo to give the title compound as
an amorphous solid (576 mg, yield: 94%): IR (KBr) νmax
2950, 1745, 1463, 1386, 1361, 1250, 1230, 1102, 1077,
1042, 1004 cm-1; 1H NMR (CDCl3, 300 MHz) δ 5.21 (1H,
t, J ) 3.5 Hz, H-12), 4.04 (1H, d, J ) 11.0 Hz, H-28a),
3.71 (1H, d, J ) 11.0 Hz, H-28b), 3.19 (1H, dd, J ) 11.1,
4.8 Hz, H-3), 2.06 (3H, s, OCOCH3), 1.16, 0.95, 0.93, 0.91
(each 3H, s, t-CH3), 0.89 [12H, s, SiC(CH3)3 and t-CH3],
0.88, 0.76 (each 3H, s, t-CH3), 0.041 [6H, s, Si(CH3)2];
FABMS (NBA) m/ z 599 [M + H]+ (9), 598 [M]+ (15),
539 (18), 467 (25), 407 (30), 203 (100); HRFABMS m/ z
599.4883 [M + H]+ (calcd for C38H66O3Si + H, 599.4859).
3-[(ter t-Bu t yld im et h ylsilyl)oxy]u r s-12-en -28-yl
Aceta te (15). The title compound was prepared from
3-[(tert-butyldimethylsilyl)oxy]urs-12-en-28-ol (14) (400

1176 J ournal of Natural Products, 1997, Vol. 60, No. 11
Notes
mg, 0.72 mmol) according to the same method as for 7
to give an amorphous solid (414 mg, yield: 96%): IR
(KBr) νmax 2929, 1743, 1460, 1387, 1360, 1231, 1101,
423 (65), 307 (73), 289 (47), 203 (100); HRFABMS m/ z
483.3825 [M + H]+ (calcd for C32H50O3 + H, 483.3838).
3-Oxou r s-12-en -28-yl Aceta te (17). The title com-
pound was prepared from 3-hydroxyurs-12-en-28-yl
acetate (16) (217 mg, 0.45 mmol) according to the same
method as for 9 to give an amorphous solid (212 mg,
yield: 98%): IR (KBr) νmax 2926, 1740, 1706, 1460, 1384,
1
1069, 1033, 1003 cm-1; H NMR (CDCl3, 300 MHz) δ
5.14 (1H, t, J ) 3.5 Hz, H-12), 4.07 (1H, d, J ) 11.0 Hz,
H-28a), 3.63 (1H, d, J ) 11.0 Hz, H-28b), 3.19 (1H, dd,
J ) 11.4, 4.8 Hz, H-3), 2.05 (3H, s, OCOCH3), 1.10, 0.99,
0.94 (6H, s, t-CH3 and H3-30), 0.91 (3H, s, t-CH3), 0.90
[9H, s, SiC(CH3)3], 0.82 (3H, d, J ) 6.0 Hz, H3-29), 0.76
(3H, s, t-CH3), 0.039 [6H, s, Si(CH3)2]; CIMS (NH3) m/ z
617 [M + NH4]+.
1
1360, 1231, 1032 cm-1; H NMR (CDCl3, 300 MHz) δ
5.17 (1H, t, J ) 3.7 Hz, H-12), 4.07 (1H, d, J ) 11.0 Hz,
H-28a), 3.64 (1H, d, J ) 11.0 Hz, H-28b), 2.56 (1H, m,
H-2â), 2.38 (1H, m, H-2R), 2.06 (3H, s, OCOCH3), 1.11,
1.10, 1.08, 1.06, 1.05 (each 3H, s, t-CH3), 0.94 (3H, br s,
H3-30), 0.82 (3H, d, J ) 6.3 Hz, H3-29); CIMS (NH3) m/ z
501 [M + NH4]+, 484 [M + H]+; HRFABMS m/ z
483.3830 [M + H]+ (calcd for C32H50O3 + H, 483.3838).
3-Hyd r oxyolea n -12-en -28-yl Aceta te (8). To a
mixture of 3-[(tert-butyldimethylsilyl)oxy]olean-12-en-
28-yl acetate (7) (485 mg, 0.81 mmol) was added a
solution of 48% HF in MeCN (1:9) (11 mL). The slurry
was stirred at room temperature overnight. It was
diluted with a mixture of CH2Cl2 and Et2O (1:2). After
the mixture was washed with H2O (twice), it was
worked up according to the standard method. The
filtrate was evaporated in vacuo to give a crystalline
solid (390 mg). The solid was subjected to flash column
chromatography [hexane-EtOAc (2.5:1)] to give the title
compound as crystals (357 mg, yield 91%): mp 192-
193 °C; IR (KBr) νmax 3496, 2942, 1717, 1465, 1433,
3,11-Dioxoolea n -12-en -28-yl Aceta te (10). To a
stirred mixture of chromium trioxide (3.72 g, 37 mmol),
dry pyridine (6.0 mL, 74 mmol), and CH2Cl2 (25 mL)
was added a solution of 3-oxoolean-12-en-28-yl acetate
(9) (310 mg, 0.64 mmol) in CH2Cl2 (12 mL). The
mixture was stirred at room temperature for 8.5 h. The
brown solution was decanted from the residue, which
was washed with Et2O several times. After the com-
bined organic extract was washed with 5% aqueous
NaOH solution (three times) and 5% aqueous HCl (three
times), it was worked up according to the standard
method. The filtrate was evaporated in vacuo to give a
residue (223 mg). The residue was subjected to flash
column chromatography [hexane-EtOAc (4:1)] to give
the title compound as an amorphous solid (130 mg,
yield: 41%): UV (EtOH) λmax (log ꢀ) 248 (4.11); IR (KBr)
νmax 2950, 1742, 1705, 1659, 1619, 1462, 1386, 1364,
1
1386, 1364, 1266, 1234, 1038 cm-1; H NMR (CDCl3,
300 MHz) δ 5.21 (1H, t, J ) 3.5 Hz, H-12), 4.04 (1H, d,
J ) 11.0 Hz, H-28a), 3.71 (1H, d, J ) 11.0 Hz, H-28b),
3.23 (1H, dd, J ) 10.7, 5.1 Hz, H-3), 2.06 (3H, s,
OCOCH3), 1.17, 1.00, 0.95, 0.93, 0.90, 0.88, 0.80 (each
3H, s, t-CH3); FABMS (NBA) m/ z 485 [M + H]+ (15),
484 [M]+ (28), 425 (24), 407 (25), 307 (12), 203 (100);
HRFABMS m/ z 485.3930 [M + H]+ (calcd for C32H52O3
+ H, 485.3995).
1
1231, 1043, 1001 cm-1; H NMR (CDCl3, 300 MHz) δ
5.62 (1H, s, H-12), 3.96 (1H, d, J ) 11.2 Hz, H-28a),
3.71 (1H, d, J ) 11.2 Hz, H-28b), 2.96 (1H, ddd, J )
13.7, 7.1, 4.2 Hz, H-1â), 2.64 (1H, ddd, J ) 15.9, 11.2,
7.1, H-2â), 2.42 (1H, s, H-9), 2.35 (1H, ddd, J ) 15.9,
6.5, 4.2 Hz, H-2R), 2.27 (1H, dd, J ) 13.7, 3.7 Hz, H-18),
2.07 (3H, s, OCOCH3), 2.02 (1H, ddd, J ) 13.9, 13.9,
4.4 Hz), 1.39, 1.26, 1.16, 1.09, 1.06, 0.92, 0.90 (each 3H,
s, t-CH3); 13C NMR (CDCl3, 75 MHz) δ 217.4 (C-3), 199.5
(C-11), 171.3 (OCOCH3), 169.3 (C-13), 128.7 (C-12), 70.4
(C-28), 61.3, 55.7, 48.1, 45.5, 45.1, 43.7, 42.9, 40.1, 37.0,
36.1, 34.5, 34.0, 33.1, 32.3, 31.2, 31.1, 26.6, 26.2, 23.7,
23.6, 22.3, 21.7, 21.2, 19.0, 18.7, 15.9; FABMS (NBA)
m/ z 497 [M + H]+ (100), 479 (7), 436 (9), 307 (27), 289
(17); HRFABMS m/ z 497.3645 [M + H]+ (calcd for
C32H48O4 + H, 497.3631).
3-Hyd r oxyu r s-12-en -28-yl Aceta te (16). The title
compound was prepared from 3-[(tert-butyldimethylsi-
lyl)oxy]urs-12-en-28-yl acetate (15) (367 mg, 0.61 mmol)
according to the same method as for 8 to give crystals
(246 mg, yield 83%): mp 177-178 °C; IR (KBr) νmax
3552, 2922, 1726, 1454, 1384, 1258, 1050, 1039 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 5.15 (1H, t, J ) 3.7 Hz,
H-12), 4.07 (1H, d, J ) 11.0 Hz, H-28a), 3.63 (1H, d, J
) 11.0 Hz, H-28b), 3.23 (1H, dd, J ) 10.6, 5.0 Hz, H-3),
2.05 (3H, s, OCOCH3), 1.11, 1.002, 0.996, 0.95 (each 3H,
s, t-CH3), 0.94 (3H, br s, H3-30), 0.82 (3H, d, J ) 5.7
Hz, H3-29), 0.80 (3H, s, t-CH3); CIMS (NH3) m/ z 503
[M + NH4]+, 485 [M + H]+.
3-Oxoolea n -12-en -28-yl Aceta te (9). To a stirred
solution of 3-hydroxyolean-12-en-28-yl acetate (8) (342
mg, 0.71 mmol) in Me2CO (28 mL) was added J ones’
reagent dropwise until it had a pale brown color. The
mixture was stirred at room temperature for 15 min.
After most of Me2CO was evaporated in vacuo, H2O was
added to the concentrated mixture. The aqueous mix-
ture was extracted with CH2Cl2 (three times). The
extract was worked up according to the standard
method. The filtrate was evaporated in vacuo to give
the title compound as an amorphous solid (334 mg,
yield: 98%): IR (KBr) νmax 2948, 1741, 1706, 1459, 1384,
3,11-Dioxou r s-12-en -28-yl Aceta te (18). The title
compound was prepared from 3-oxours-12-en-28-yl ace-
tate (17) (100 mg, 0.21 mmol) according to the same
method as for 10 to give an amorphous solid (39 mg,
yield: 38%): UV (EtOH) λmax (log ꢀ) 247 (4.03) nm; IR
(KBr) νmax 2930, 1740, 1704, 1657, 1617, 1460, 1386,
1
1364, 1238, 1035 cm-1; H NMR (CDCl3, 300 MHz) δ
5.56 (1H, s, H-12), 3.97 (1H, d, J ) 11.2 Hz, H-28a),
3.63 (1H, d, J ) 11.2 Hz, H-28b), 2.93 (1H, ddd, J )
13.4, 7.0, 3.9 Hz, H-1â), 2.66 (1H, ddd, J ) 15.9, 11.5,
7.0 Hz, H-2â), 2.41 (1H, s, H-9), 2.35 (1H, ddd, J ) 15.9,
6.2, 3.9 Hz, H-2R), 2.06 (3H, s, OCOCH3), 2.06 (1H, ddd,
J ) 13.7, 13.7, 4.8 Hz), 1.83 (1H, ddd, J ) 13.7, 13.7,
5.1 Hz), 1.33, 1.30, 1.20, 1.10, 1.07 (each 3H, s, t-CH3),
0.97 (3H, br s, H3-30), 0.83 (3H, d, J ) 6.3 Hz, H3-29);
13C NMR (CDCl3, 75 MHz) δ 217.3 (C-3), 199.0 (C-11),
171.3 (OCOCH3), 163.5 (C-13), 131.0 (C-12), 70.7 (C-
1
1362, 1232, 1042 cm-1; H NMR (CDCl3, 300 MHz) δ
5.23 (1H, t, J ) 3.5 Hz, H-12), 4.04 (1H, d, J ) 11.0 Hz,
H-28a), 3.72 (1H, d, J ) 11.0 Hz, H-28b), 2.57 (1H, m,
H-2â), 2.36 (1H, m, H-2R), 2.07 (3H, s, OCOCH3), 1.18,
1.10, 1.07, 1.06, 1.01, 0.90, 0.88 (each 3H, s, t-CH3);
FABMS (NBA) m/ z 483 [M + H]+ (82), 482 [M]+ (44),

Notes
J ournal of Natural Products, 1997, Vol. 60, No. 11 1177
28), 61.1, 55.8, 54.3, 48.1, 45.2, 43.9, 40.1, 39.3, 39.2,
37.5, 36.9, 35.3, 34.5, 32.4, 30.4, 26.9, 26.5, 23.3, 21.8,
21.3, 21.2, 20.9, 19.0, 18.5, 17.6, 16.0; CIMS (NH3) m/ z
515 [M + NH4]+, 498 [M + H]+; HRFABMS m/ z
497.3642 [M + H]+ (calcd for C32H48O4 + H, 497.3631).
28-Hyd r oxyolea n -12-en e-3,11-d ion e (Kr u k ovin e
A) (1). A mixture of 3,11-dioxoolean-12-en-28-yl acetate
(10) (72 mg, 0.14 mmol), KOH (420 mg), and MeOH (4.2
mL) was stirred at room temperature for 30 min. After
the mixture was acidified with 5% aqueous HCl, it was
extracted with a mixture of CH2Cl2 and Et2O (1:2) (three
times). The extract was worked up according to the
standard method. The filtrate was evaporated in vacuo
to afford the crude title compound (66 mg, yield:
quantitative) as a crystalline solid. It was recrystallized
from MeOH to give the title compound (39 mg) as
colorless crystals: mp 233-235 °C; [R]22D +90.2° (c 0.18,
CHCl3); UV (MeOH) λmax (log ꢀ) 251 (4.17) nm; IR (KBr)
νmax 3438, 2946, 2856, 1703, 1652, 1611, 1458, 1385,
) 11.2 Hz, H-28b), 2.92 (1H, ddd, J ) 13.4, 7.1, 3.9 Hz,
H-1â), 2.66 (1H, ddd, J ) 15.9, 11.2, 7.1 Hz, H-2â), 2.42
(1H, s, H-9), 2.36 (1H, ddd, J ) 15.9, 6.4, 3.9 Hz, H-2R),
2.01 (1H, ddd, J ) 13.7, 13.7, 4.6 Hz), 1.86 (1H, ddd, J
) 13.7, 13.7, 3.8 Hz), 1.33, 1.30, 1.19, 1.10, 1.07 (each
3H, s, t-CH3), 0.97 (3H, br s, H3-30), 0.82 (3H, d, J )
6.3 Hz, H3-29); 13C NMR (CDCl3, 75 MHz) δ 217.4 (C-
3), 199.2 (C-11), 164.5 (C-13), 130.7 (C-12), 70.0 (C-28),
61.0, 55.7, 54.3, 48.1, 45.2, 44.0, 40.1, 39.5, 39.3, 38.7,
36.8, 35.1, 34.5, 32.4, 30.5, 26.9, 26.6, 22.9, 21.8, 21.4,
20.8, 19.1, 18.5, 17.7, 16.1; EIMS (70 eV) m/ z 454 [M]+
(56), 439 (16), 426 (24), 289 (100), 248 (74); HREIMS
m/ z 454.3473 [M]+ (calcd for C30H46O3, 454.3447).
Ack n ow led gm en ts. This investigation was sup-
ported by funds from the Norris Cotton Cancer Center.
We thank Drs. Larry W. Reilly and Sheng-Yuh Tang
(Rhone-Poulenc Rorer), Dr. Stephen W. Wright (Pfizer),
Dr. Mary K. Young and Mr. Ron New (UC Riverside)
for the mass spectra, and Professor David A. Evans and
Mr. Brett D. Allison (Harvard University) for the optical
rotation measurements. We also thank Dr. Hideji
Itokawa (Tokyo University of Pharmacy and Life Sci-
1365, 1259, 1208, 1110, 1064, 1002 cm-1 1H NMR
;
(CDCl3, 300 MHz) δ 5.61 (1H, s, H-12), 3.49 (1H, d, J )
11.0 Hz, H-28a), 3.24 (1H, d, J ) 11.0 Hz, H-28b), 2.95
(1H, ddd, J ) 13.7, 7.1, 4.2 Hz, H-1â), 2.63 (1H, ddd, J
) 15.9, 11.1, 7.1, H-2â), 2.44 (1H, s, H-9), 2.36 (1H, ddd,
J ) 15.9, 6.6, 4.2 Hz, H-2R), 2.18 (1H, dd, J ) 13.4, 4.0
Hz, H-18), 1.96 (1H, ddd, J ) 13.7, 13.7, 4.4 Hz), 1.40,
1
ence) for furnishing H- and 13C-NMR spectra of kruk-
ovines A and B.
Refer en ces a n d Notes
1.26, 1.15, 1.11, 1.07, 0.92, 0.90 (each 3H, s, t-CH3); 13
C
(1) (a) Tang, W.; Elsenbrand, G. In Chinese Drugs of Plant Origin;
Springer-Verlag: Berlin, 1992; pp 1-1056. (b) Yu, L.; Ma, R.;
Wang, Y.; Nishino, H.; Takayasu, J .; He, W.; Chang, M.; Zhen,
J .; Liu, W.; Fan, S. Int. J . Cancer 1992, 50, 635-638. (c)
Umehara, K.; Takagi, R.; Kuroyanagi, M.; Ueno, A.; Taki, T.;
Chen, Y.-J . Chem. Pharm. Bull. 1992, 40, 401-405. (d) Huang,
M.-T.; Ho, C.-T.; Wang, Z. Y.; Ferraro, T.; Lou, Y.-R.; Stauber,
K.; Ma, W.; Georgiadis, C.; Laskin, J . D.; Conney, A. H. Cancer
Res. 1994, 54, 701-708. (e) Liu, J .; Liu, Y.; Mao, Q.; Klaassen,
C. D. Fundam. Appl. Toxicol. 1994, 22, 34-40. (f) Honda, T.;
Finlay, H. J .; Gribble, G. W.; Suh, N.; Sporn, M. B. Bioorg. Med.
Chem. Lett. 1997, 7, 1623-1628. (g) Finlay, H. J .; Honda, T.;
Gribble, G. W.; Danielpour, D.; Benoit, N. E.; Suh, N.; Williams,
C.; Sporn, M. B. Bioorg. Med. Chem. Lett. 1997, 7, 1769-1772.
(2) Shirota, O.; Tamemura, T.; Morita, H.; Takeya, K.; Itokawa, H.
J . Nat. Prod. 1996, 59, 1072-1075.
NMR (CDCl3, 75 MHz) δ 217.5 (C-3), 199.7 (C-11), 170.3
(C-13), 128.4 (C-12), 69.9 (C-28), 61.3, 55.7, 48.1, 45.5,
45.2, 43.8, 43.0, 40.0, 37.3, 37.0, 34.5, 34.1, 33.2, 32.3,
31.3, 30.9, 26.7, 26.1, 23.7, 23.6, 21.8, 21.7, 19.1, 18.7,
16.0; FABMS (NBA) m/ z 455 [M + H]+ (100), 437 (12),
391 (8), 307 (66), 289 (37), 220 (18); HRFABMS m/ z
455.3521 [M + H]+ (calcd for C30H46O3 + H, 455.3525).
28-Hyd r oxyu r s-12-en e-3,11-d ion e (Kr u k ovin e B)
(2). The title compound was prepared from 3,11-
dioxours-12-en-28-yl acetate (18) (30 mg, 0.60 mmol)
according to the same method as for 1 to afford a
crystalline solid (27 mg, yield: 98%). It was recrystal-
lized from MeOH to give the title compound (19 mg) as
colorless crystals: mp 250-251 °C; [R]22D +95.2° (c 0.10,
CHCl3); UV (MeOH) λmax (log ꢀ) 251 (3.96) nm; IR (KBr)
νmax 3415, 2979, 2954, 2931, 2873, 2860, 1706, 1633,
1458, 1386, 1316, 1276, 1210, 1136, 1106, 1060, 1048,
(3) Corey, E. J .; Venkateswarlu, A. J . Am. Chem. Soc. 1972, 94,
6190-6191.
(4) Simonsen, J .; Ross, W. C. J . In The Terpenes; Cambridge
University: Cambridge, 1957; Vol. 5, pp 221-285.
(5) Newton, R. F.; Reynolds, D. P.; Finch, M. A. W.; Kelly, D. R.;
Roberts, S. M. Tetrahedron Lett. 1979, 3981-3982.
(6) Tsuyuki, T.; Hamada, Y.; Honda, T.; Takahashi, T.; Matsushita,
K. Bull. Chem. Soc. J pn. 1979, 52, 3127-3128.
(7) J acobs W. A.; Fleck, E. E. J . Biol. Chem. 1931, 92, 487-494.
1
1028 cm-1; H NMR (CDCl3, 300 MHz) δ 5.56 (1H, s,
H-12), 3.47 (1H, d, J ) 11.2 Hz, H-28a), 3.18 (1H, d, J
NP9702897