Synthetic oleanane and ursane triterpenoids with modified rings A and C: A series of highly active inhibitors of nitric oxide production in mouse macrophages

Article abstract of DOI:10.1021/jm0002230

We have designed and synthesized 16 new olean- and urs-1-en-3-one triterpenoids with various modified rings C as potential antiinflammatory and cancer chemopreventive agents and evaluated their inhibitory activities against production of nitric oxide induced by interferon-γ in mouse macrophages. This investigation revealed that 9(11)-en-12-one and 12-en-11-one functionalities in ring C increase the potency by about 2-10 times compared with the original 12-ene. Subsequently, we have designed and synthesized novel olean- and urs-1-en-3-one derivatives with nitrile and carboxyl groups at C-2 in ring A and with 9(11)-en-12-one and 12-en-11-one functionalities in ring C. Among them, we have found that methyl 2-cyano-3, 12-dioxooleana-1,9(11)-dien-28-oate (25), 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO) (26), and methyl 2-carboxy-3,12-dioxooleana-1,9(11)-dien-28-oate (29) have extremely high potency (IC₅₀ = 0.1 nM level). Their potency is similar to that of dexamethasone although they do not act through the glucocorticoid receptor. Overall, the combination of modified rings A and C increases the potency by about 10 000 times compared with the lead compound, 3-oxooleana-1,12-dien-28-oic acid (8) (IC₅₀ = 1 μM level). The selected oleanane triterpenoid, CDDO (26), was found to be a potent, multifunctional agent in various in vitro assays and to show antiinflammatory activity against thioglycollate-interferon-γ-induced mouse peritonitis.

Full text of DOI:10.1021/jm0002230

J . Med. Chem. 2000, 43, 4233-4246
4233
Syn th etic Olea n a n e a n d Ur sa n e Tr iter p en oid s w ith Mod ified Rin gs A a n d C: A
Ser ies of High ly Active In h ibitor s of Nitr ic Oxid e P r od u ction in Mou se
Ma cr op h a ges†
Tadashi Honda,‡ BarbieAnn V. Rounds,‡ Lothar Bore,‡,| Heather J . Finlay,‡, Frank G. Favaloro, J r.,‡
Nanjoo Suh,§ Yongping Wang,§ Michael B. Sporn,*,§ and Gordon W. Gribble*,‡
Department of Chemistry, Dartmouth College, and Department of Pharmacology and Toxicology, Dartmouth Medical School,
Hanover, New Hampshire 03755
Received May 26, 2000
We have designed and synthesized 16 new olean- and urs-1-en-3-one triterpenoids with various
modified rings C as potential antiinflammatory and cancer chemopreventive agents and
evaluated their inhibitory activities against production of nitric oxide induced by interferon-γ
in mouse macrophages. This investigation revealed that 9(11)-en-12-one and 12-en-11-one
functionalities in ring C increase the potency by about 2-10 times compared with the original
12-ene. Subsequently, we have designed and synthesized novel olean- and urs-1-en-3-one
derivatives with nitrile and carboxyl groups at C-2 in ring A and with 9(11)-en-12-one and
12-en-11-one functionalities in ring C. Among them, we have found that methyl 2-cyano-3,
12-dioxooleana-1,9(11)-dien-28-oate (25), 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO)
(26), and methyl 2-carboxy-3,12-dioxooleana-1,9(11)-dien-28-oate (29) have extremely high
potency (IC50 ) 0.1 nM level). Their potency is similar to that of dexamethasone although they
do not act through the glucocorticoid receptor. Overall, the combination of modified rings A
and C increases the potency by about 10 000 times compared with the lead compound,
3-oxooleana-1,12-dien-28-oic acid (8) (IC50 ) 1 µM level). The selected oleanane triterpenoid,
CDDO (26), was found to be a potent, multifunctional agent in various in vitro assays and to
show antiinflammatory activity against thioglycollate-interferon-γ-induced mouse peritonitis.
In tr od u ction
of derivatives of commercially available oleanolic acid
(1) and ursolic acid (2) (cf. Scheme 1).
Oleanane and ursane triterpenoids are pentacyclic
compounds with 30 carbon atoms, biosynthetically
derived from the cyclization of squalene.1 This is a vast
class of natural products whose structural diversity
includes a wide array of functional groups.2 Many
compounds of this group are reported to have various
interesting biological, pharmacological, or medicinal
activities including antiinflammatory and anticarcino-
genic activities.3 However, in many cases, the potency
of these triterpenoids is relatively weak. Therefore,
anticipating highly potent novel structures, we began
bioassay-directed systematic drug design and synthesis
To discover antiinflammatory and cancer chemopre-
ventive drugs from these derivatives, we have adopted
an assay system that measures inhibition of nitric oxide
(NO) production induced by interferon-γ (IFN-γ) in
mouse macrophages4 as a preliminary screening assay
system. In a previous paper,5 we reported that olean-
12-ene triterpenoids with a 1-en-3-one functionality
having nitrile, methoxycarbonyl, and carboxyl groups
at C-2 in ring A, 3-7, show significant potency [IC50
)
0.01-0.1 µM level, about 10-100 times more potent
than the lead compound 8 (IC50 ) 1 µM level)] in this
assay. As a continuation of this work, we have synthe-
sized 16 new olean- and urs-1-en-3-one derivatives with
various modified rings C, 9-24, and evaluated their
inhibitory activities in the above assay. This investiga-
tion revealed that 9(11)-en-12-one, 12-en-11-one, and 13-
(18)-en-11-one functionalities in ring C increase the
potency by about 2-10 times compared with the original
12-ene. Subsequently, we have designed and synthe-
sized novel olean- and urs-1-en-3-one derivatives with
nitrile, methoxycarbonyl, and carboxyl groups at C-2 in
ring A and with 9(11)-en-12-one, 12-en-11-one, and 13-
(18)-en-11-one functionalities in ring C, 25-35. Among
them, we have found that methyl 2-cyano-3,12-di-
oxooleana-1,9(11)-dien-28-oate (25), 2-cyano-3,12-di-
oxooleana-1,9(11)-dien-28-oic acid (CDDO) (26), and
methyl 2-carboxy-3,12-dioxooleana-1,9(11)-dien-28-oate
(29) have extremely high potency (IC50 ) 0.1 nM level).
We report here the synthesis, inhibitory activity, and
† Part of this work has been reported in preliminary form: (a)
Honda, T.; Finlay, H. J .; Gribble, G. W.; Suh, N.; Sporn, M. B. New
enone derivatives of oleanolic acid and ursolic acid as inhibitors of nitric
oxide production in mouse macrophages. Bioorg. Med. Chem. Lett.
1997, 7, 1623-1628. (b) Honda, T.; Rounds, B. V.; Gribble, G. W.; Suh,
N.; Wang, Y.; Sporn, M. B. Design and synthesis of 2-cyano-3,12-
dioxooleana-1,9-dien-28-oic acid, a novel and highly active inhibitor
of nitric oxide production in mouse macrophages. Bioorg. Med. Chem.
Lett. 1998, 8, 2711-2714. (c) Honda, T.; Rounds, B. V.; Bore, L.;
Favaloro, F. G., J r.; Gribble, G. W.; Suh, N.; Wang, Y.; Sporn, M. B.
Novel synthetic oleanane triterpenoids:
a series of highly active
inhibitors of nitric oxide production in mouse macrophages. Bioorg.
Med. Chem. Lett. 1999, 9, 3429-3434.
* Address correspondence to either author. For M.B.S.: phone, 603-
650-6557; fax, 603-650-1129; e-mail, Michael.Sporn@dartmouth.edu.
For G.W.G.: phone, 603-646-3118; fax, 603-646-3946; e-mail, Grib@
dartmouth.edu.
‡ Department of Chemistry.
§ Department of Pharmacology and Toxicology.
| Present address: Ciba Specialty Chemicals Schweizerhalle Inc.,
Postfach 1130, CH-4133 Pratteln, Switzerland.
Present address: The Bristol-Myers Squibb Pharmaceutical Re-
search Institute, P.O. Box 5400, Princeton, NJ 08543-5400.
10.1021/jm0002230 CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/13/2000

4234 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
Sch em e 1a
a
Reagents: (a) CH2N2, Et2O, THF; (b) Ac2O, pyr; (c) CrO3, pyr, CH2Cl2; (d) KOH, aq MeOH; (e) J ones; (f) PhSeCl, EtOAc, 30% H2O2,
THF; (g) LiI, DMF.
Sch em e 2a
a
Reagents: (a) CH2N2, Et2O, THF; (b) Ac2O, pyr; (c) 30% H2O2, AcOH; (d) Br2, HBr, AcOH; (e) KOH, aq MeOH; (f) J ones; (g) PhSeCl,
EtOAc, 30% H2O2, THF; (h) LiI, DMF; (i) NH2NH2, KOH, diethylene glycol; (j) mCPBA, CH2Cl2.
structure-activity relationships (SARs) of these novel
(LiI) in N,N-dimethylformamide (DMF)9 gave R,â- and
â,γ-unsaturated ketones 12 and 15 in 43% and 22%
yield, respectively. C-3 alcohol 47 was obtained quan-
titatively by alkaline hydrolysis (reflux) of known
acetate 46,10 which was prepared in three steps from
ursolic acid (2). J ones oxidation of 47 gave C-3 ketone
48 in 89% yield. Enone 13 was prepared in 93% yield
from 48 by the same method as for 11. Halogenolysis
of 13 gave acid 14 in 58% yield.11
Similarly, enone 16 was synthesized in 74% yield via
50 and 51 from C-12 ketone 49, which was prepared in
three steps from 1 according to a known method,12,13
and enone 9 was also synthesized in 60% yield via 53
and 54 from known C-12 ketone 52 which was prepared
from 49 with bromine and hydrobromic acid in acetic
acid.14 Halogenolysis of enones 16 and 9 gave acids 17
and 10 in 62% and 68% yield, respectively. Enone 19
triterpenoids in detail.
Ch em istr y
Mod ifica tion of Rin g C a n d Ca r boxyl Gr ou p a t
C-17. Enones 9-21 were designed and synthesized to
discover what structures of ring C enhance potency in
comparison with the original 12-ene, i.e., the lead
compound 85 (Schemes 1-3).6 In addition, enones 22-
24 were designed and synthesized to learn which
functionality at C-17 is most appropriate (Scheme 4).
Enone 11 was prepared by introduction of a double
bond at C-1 of known C-3 ketone 45,7 which was
prepared in five steps from oleanolic acid (1), with
phenylselenenyl chloride in ethyl acetate and sequential
addition of 30% hydrogen peroxide (PhSeCl-H2O2)
(yield, 97%).8 Halogenolysis of 11 with lithium iodide

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4235
Sch em e 3a
oxidation of 18 with m-chloroperbenzoic acid (mCPBA)
in methylene chloride (CH2Cl2). Enone 20 was synthe-
sized in 37% yield via 60 from known diene 5917 which
was prepared in five steps from 1. Interestingly, J ones
oxidation of 20 afforded the same deconjugated enone
15 (yield, 28%) as halogenolysis of 11. Enone 22 was
prepared in 83% yield from krukovine A acetate (61),
which was previously synthesized in our laboratory.18
Alkaline hydrolysis (at room temperature)19 of 22 gave
enone 23 in 78% yield. Ratcliffe oxidation20 of 23 with
chromium trioxide and pyridine in CH2Cl2 afforded
aldehyde 24 in 89% yield.
a
Among these new synthetic enones, 9-12 and 15
showed more inhibitory activity than the lead compound
8 on production of NO-induced IFN-γ in mouse macro-
phages (see Table 1). Overall, 9(11)-en-12-one, 12-en-
11-one, and 13(18)-en-11-one functionalities in ring C
increase the potency by about 2-10 times compared
with the original 12-ene.
Reagents: (a) CH2N2, Et2O, THF; (b) Ac2O, pyr; (c) SeO2,
AcOH; (d) KOH, aq MeOH; (e) CrO3, pyr, CH2Cl2; (f) PhSeCl,
EtOAc, 30% H2O2, THF; (g) LiI, DMF; (h) J ones.
Sch em e 4a
Com bin a tion of Mod ified Rin g A w ith Rin g C.
On the basis of our previous results,5 in which olean-
12-ene triterpenoids with a 1-en-3-one functionality
having nitrile, methoxycarbonyl, and carboxyl groups
at C-2 in ring A, 3-7, are about 10-100 times more
potent than 8 (see Table 1), and the above results, we
have designed and synthesized novel oleanane and
ursane triterpenoids with modified rings A and C, 25-
35. In addition, to further discern SARs, amide 36 and
enal 37 were designed and synthesized because amide
41 and enal 42 showed low potency and toxicity,
respectively, in our previous evaluation (see Table 1).5
The syntheses of these newly designed triterpenoids are
illustrated in Schemes 5-7.
a
Reagents: (a) PhSeCl, EtOAc, 30% H2O2, THF; (b) KOH, aq
MeOH; (c) CrO3, pyr, CH2Cl2.
was obtained in 68% yield from known C-3 ketone 5615
which was synthesized via 55 from 49. Enone 18 was
obtained in 76% yield via 58 from acid 57, which was
prepared in 53% yield from 52 by Wolff-Kishner
reduction. Epoxide 2116 was prepared in 46% yield by
Hydroxymethylene 6221 was prepared in 99% yield
by formylation of 54 with ethyl formate in the presence
Sch em e 5a
a
Reagents: (a) HCO2Et, NaOMe, PhH; (b) NH2OH‚HCl, aq EtOH; (c) NaOMe, Et2O, MeOH; (d) DDQ, PhH; (e) LiI, DMF.

4236 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
Sch em e 6a
a
Reagents: (a) Stiles' reagent, DMF; (b) CH2N2, Et2O, THF; (c) PhSeCl, pyr, CH2Cl2, 30% H2O2, CH2Cl2; (d) KOH, aq MeOH; (e) LiI,
DMF; (f) H2SO4, MeOH; (g) NH3, MeOH; (h) SiO2.
Sch em e 7a
obtained in 82% yield from 30. Amide 36 was prepared
selectively from 27 with saturated ammonia-MeOH
(yield, 49%; 88% based on recovered 27). Enal 37 was
synthesized from 62 according to the same method as
for 27 (yield, 62%; 74% based on recovered 62).
Biologica l Resu lts a n d Discu ssion
The inhibitory activities [IC50 (µM) value] of synthetic
triterpenoids 3-44, oleanolic acid (1), ursolic acid (2),
hydrocortisone, and dexamethasone (both glucocoriti-
coids are used as positive controls) on NO production
induced by IFN-γ in mouse macrophages are shown in
Table 1. These derivatives are arranged categorically
in order of the amplification of potency due to the
structure of ring C. Among novel synthetic oleanane and
ursane triterpenoids, 25, CDDO (26), and 29 showed
extremely high potency (IC50 ) 0.1 nM level). Their
potency is equivalent to that of dexamethasone although
their inhibitory activity is not blocked by the glucocor-
ticoid antagonist, RU-486,28 which reverses the action
of dexamethasone (data not shown).
This series of synthetic triterpenoids showed the
following interesting SARs: (1) A 9(11)-en-12-one func-
tionality is the strongest enhancer of potency among
structures of ring C. Oleanane triterpenoids 10 and 9
(IC50 ) 0.1 µM level) are about 10-100 times more
potent than the lead compounds 8 (IC50 ) 1 µM level)
and 43 (IC50 ) 10 µM level), respectively. (2) 12-En-11-
one, 13(18)-en-11-one, and 12-one functionalities also
enhance potency. Oleanane triterpenoids 11, 12, 15, and
17 are more potent than 8. Also, ursane triterpenoids
13 and 14 are more potent than 44. (3) A 9(11)-ene
functionality shows similar potency to the original 12-
ene (compare 18 with 8). (4) The saturated ring C, 11,-
13(18)-diene, and 9,11-epoxide are less potent than the
original 12-ene (compare 19-21 with 8). (5) Carboxyl,
methoxycarbonyl, and nitrile groups at C-2 enhance
potency.5 Oleanane triterpenoids 3-7 (IC50 ) 0.01-0.1
µM level) are about 10-100 times more potent than 8.
Ursane triterpenoids 38 and 39 are more potent than
44. (6) The combination of a 9(11)-en-12-one functional-
ity with nitrile and carboxyl groups at C-2 enhances the
potency synergistically. Oleanane triterpenoids 25, CDDO
(26), and 29 (IC50 ) 0.1 nM level) are about 10 000 times
more potent than 8 (see Figure 1). (7) Although com-
pounds 27 and 30 were also expected to show similar
a
Reagents: (a) PhSeCl, pyr, CH2Cl2, 30% H2O2, CH2Cl2.
of sodium methoxide in benzene.22 Isoxazole 63 was
obtained in 66% yield from 62 by the addition of
hydroxylamine.23 Cleavage of the isoxazole moiety of 63
with sodium methoxide gave nitrile 64 quantita-
tively.23,24 CDDO methyl ester (25) was prepared in 92%
yield by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)
oxidation of 64 in benzene, although PhSeCl-H2O2 gave
25 in only 40% yield. Halogenolysis of 25 gave CDDO
(26) in 68% yield. Similarly, olean-12-en-11-one deriva-
tive 31 was synthesized in 53% yield via 65,21 66, and
6724 from 45. Halogenolysis of 31 gave R,â- and â,γ-
unsaturated ketones 32 and 35 in 37% and 16% yield,
respectively. Urs-12-en-11-one derivative 33 was also
synthesized in 61% yield via 68,21 69, and 7024 from 48.
Halogenolysis of 33 gave acid 34 in 60% yield.11
Ester 71 was prepared in 78% yield from C-3 ketone
54 by Stiles’ reagent (methoxymagnesium methyl car-
bonate) in DMF,25 followed by methylation with diazo-
methane. 1H NMR showed that 71 in CDCl3 is the single
tautomer depicted in Scheme 6. Enone 27 was prepared
from 71 by PhSeCl-pyridine in CH2Cl2 and sequential
26
addition of 30% H2O2 (yield, 71%; 88% based on
recovered 71). Hydrolysis (reflux) of 27 with potassium
hydroxide in aqueous methanol (MeOH) gave C-2 car-
boxylic acid 29 and decarboxylated enone 9 in 78% and
8% yield, respectively. Because of the steric hindrance
of the methoxycarbonyl group at C-17 of 27, the above
conditions gave monoesters 29 and 9 selectively. Halo-
genolysis of 29 gave dicarboxylic acid 30 and decarboxy-
lated enone 10 in 47% and 24% yield, respectively.
Interestingly, methylation of 30 with MeOH under
acidic conditions gave a mixture of desired monoester
28 and Michael adduct 72.27 The ratio of 28 to 72 was
1
determined to be 4:5 by H NMR. Because the adduct
72 was readily transformed into 28 under purification
conditions (see Experimental Section), 28 was finally

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4237
Ta ble 1. Activity of Olean-1-en-3-one and Urs-1-en-3-one Triterpenoids

4238 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Ta ble 1 (Continued)
Honda et al.
a
b
O, olean-1-en-3-one; U, urs-1-en-3-one. C, H, and N analyses were within (0.4% of the theoretical values. c Details of the evaluation
method are described in the Experimental Section. IC50 values of compounds 7, 25, 26, 29, 31, 32, 35, hydrocortisone, and dexamethasone
were determined in the range of 0.1 pM-1 µM (10-fold dilutions). The other compounds were assayed in the range of 0.01-40 µM (4-fold
d
dilutions). Values are an average of two separate experiments. Compounds 27 and 42 were toxic to cells above 1 µM and were not active
below 1 µM. e Ursolic acid (2) was toxic to cells above 10 µM and was not active below 10 µM.
31, 32, and 35 (IC50 ) 0.01 µM level) are about 100
times more potent than 8. Also, ursane triterpenoids 33
and 34 (IC50 ) 0.1 µM level) are about 100 times more
potent than 44 (IC50 ) 10 µM level). (10) The oleanane
skeleton is more potent than the ursane skeleton.
Oleanane derivatives 3, 4, 8, 11, 12, 31, and 32 are more
potent than ursane derivatives 38, 39, 44, 13, 14, 33,
and 34, respectively. (11) Acetoxymethyl, hydroxy-
methyl, and formyl groups at C-17 decrease potency
compared with the carboxyl group at C-17 (compare 22-
24 with 12). (12) The role of methoxycarbonyl and
carboxyl groups at C-17 is ambiguous. In some ana-
logues, the carboxyl group is more potent than the
methoxycarbonyl group: acids 7, 8, 17, and 28 are more
potent than esters 6, 43, 16, and 27, respectively. For
other analogues, the carboxyl and methoxycarbonyl
groups show similar potency: acids 4, 26, 32, and 39
show similar potency to esters 3, 25, 31, and 38,
respectively. Acids and esters with a nitrile group at
C-2 seem to show this tendency although the reason is
unknown. Lastly, acids 30 and 40 are less potent than
esters 29 and 5, respectively.
F igu r e 1. SARs between CDDO (26) and its lead compounds
4, 8, and 10.
The selected oleanane triterpenoid, 2-cyano-3,12-
dioxooleana-1,9(11)-dien-28-oic acid (CDDO) (26), was
found to be a potent, multifunctional agent in various
in vitro assays.29 For example, CDDO induces monocytic
differentiation of human myeloid leukemia cells and
adipogenic differentiation of mouse 3T3-L1 fibroblasts.30
CDDO inhibits proliferation of many human tumor cell
lines. CDDO blocks de novo synthesis of inducible nitric
oxide synthase (iNOS) and inducible cyclooxygenase
(COX-2) in mouse macrophages. CDDO will protect rat
brain hippocampal neurons from cell death induced by
â-amyloid. The above potencies have been found at
concentrations ranging from 10-6 to 10-9 M in cell
culture. In addition, CDDO shows antiinflammatory
activity against thioglycollate-IFN-γ-induced mouse
peritonitis (0.1 µmol of CDDO/mouse, ip: a complete
high potency to CDDO from the perspective of SARs,
they did not (compare them with 5 and 7). The reason
diacid 30 did not show high potency might be that the
higher polarity than that of monoacids 26 and 29
influences the bioavailability and permeability toward
macrophages. (8) The combination of a 9(11)-en-12-one
functionality with amide and formyl groups at C-2 does
not enhance potency as strongly as a nitrile or carboxyl
group as expected from the consideration of the activity
of oleana-1,12-dien-3-one with amide and formyl groups
at C-2 (compare 36 and 37 with 41 and 42, respectively).
(9) The combination of 12-en-11-one and 13(18)-en-11-
one functionalities with a nitrile group at C-2 also
strongly enhances the potency. Oleanane triterpenoids

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4239
7.33 (1H, d, J ) 10.6 Hz), 6.02 (1H, s), 5.93 (1H, d, J ) 10.6
Hz), 3.02 (1H, ddd, J ) 3.4, 4.9, 13.7 Hz), 2.96 (1H, d, J ) 4.9
Hz), 1.41, 1.32, 1.19, 1.11, 1.02, 1.00, 0.90 (each 3H, s). 13C
NMR (CDCl3): δ 203.8, 199.6, 183.9, 171.7, 155.0, 126.1, 123.8,
49.9, 48.4, 47.2, 45.8, 44.8, 42.2, 41.9, 35.9, 34.6, 33.4, 33.1,
32.3, 31.6, 30.8, 28.2, 27.3, 27.1, 24.8, 23.2, 22.7, 21.83, 21.75,
18.5. EIMS (70 eV) m/z: 466 [M]+ (100), 451 (42), 301 (17),
244 (45). HREIMS Calcd for C30H42O4: 466.3083. Found:
466.3064. Anal. (Table 1).
suppression of both NO production and iNOS protein
synthesis; 0.01 µmol of CDDO/mouse, ip: more than
50% suppression in these measurements).31 CDDO may
be a potential drug candidate for inflammatory diseases
and chemoprevention of cancer.
Currently, further biological evaluation of CDDO, 25,
and 29 in vitro and in vivo for both antiinflammation
and chemoprevention is in progress. Further studies on
the mechanism of action of these compounds also are
in progress.
Meth yl 3,11-Dioxoolea n a -1,12-d ien -28-oa te (11). 11 was
prepared from methyl 3,11-dioxoolean-12-en-28-oate (45)7 ac-
cording to the same method as for 9 to give a crystalline solid
(97%). This material was used for the next reaction without
further purification. An analytically pure sample was obtained
by flash column chromatography [hexanes-EtOAc (3:1)],
followed by recrystallization from a mixture of hexanes and
EtOAc (3:1) as crystals: mp 189-191 °C; [R]24D +152° (c 0.34,
CHCl3). UV (EtOH) λmax (log ꢀ): 248 (4.26) nm. IR (KBr): 2942,
2861, 1725, 1666, 1648 cm-1. 1H NMR (CDCl3): δ 7.79 (1H, d,
J ) 10.3 Hz), 5.81 (1H, d, J ) 10.3 Hz), 5.74 (1H, s), 3.66 (3H,
s), 3.05 (1H, dd, J ) 4.6, 14.9 Hz), 2.67 (1H, s), 2.08 (1H, ddd,
J ) 4.0, 13.7, 13.7 Hz), 1.39 (6H, s), 1.16, 1.11, 0.97, 0.96, 0.95
(each 3H, s). 13C NMR (CDCl3): δ 204.7, 199.3, 177.6, 170.4,
161.8, 127.6, 124.8, 55.7, 52.9, 52.1, 46.3, 45.3, 44.9, 44.4, 43.9,
42.0, 39.1, 33.8, 33.0, 32.3, 31.7, 30.9, 28.0, 27.8, 23.8, 23.6,
23.0, 21.7, 20.1, 19.4, 18.3. EIMS (70 eV) m/z: 480 [M]+ (88),
465 (15), 421 (24), 397 (52), 276 (36), 257 (47), 217 (100).
HREIMS Calcd for C31H44O4: 480.3240. Found: 480.3231.
Anal. (Table 1).
Exp er im en ta l Section
Gen er a l Exp er im en ta l P r oced u r es. Melting points were
determined on
a Thomas-Hoover capillary melting point
apparatus and are uncorrected. Optical rotations were mea-
sured with a J asco DIP-181 digital polarimeter. UV and IR
spectra were recorded on a Hewlett-Packard 8451A UV/VIS
spectrophotometer and a Perkin-Elmer 600 series FTIR spec-
1
trophotometer, respectively. H (300 MHz) and 13C (75 MHz)
NMR spectra were recorded on a Varian XL-300 Fourier
transform spectrometer unless otherwise stated. The chemical
shifts are reported in δ (ppm) using the δ 7.27 signal of CHCl3
(1H NMR) and δ 77.23 signal of CDCl3 (13C NMR) as an
internal standard unless otherwise stated. Low-resolution
mass spectra and high-resolution MS data were obtained on
a Micromass 70-VSE unless otherwise stated. Elemental
microanalysis was performed by Atlantic Microlab Inc. TLC
and preparative TLC (prep-TLC) were performed with Merck
precoated TLC plates silica gel 60 F254. Flash column chro-
matography was done with Select Scientific silica gel (230-
400 mesh). The standard workup method was as follows: an
organic extract was washed with saturated aqueous NaHCO3
solution (three times) followed by saturated aqueous NaCl
solution (three times), then dried over anhydrous MgSO4, and
filtered. The filtrate was evaporated in vacuo.
3,11-Dioxoolea n a -1,12-d ien -28-oic Acid (12) a n d 3,11-
Dioxoolea n a -1,13(18)-d ien -28-oic Acid (15). 12 and 15 were
prepared from 11 by the similar method as for 10 except that
the reaction time was 2 h. The reaction mixture was subjected
to prep-TLC [hexanes-EtOAc (3:5)] to give 12 as an amor-
phous solid (43%) and 15 as a crystalline solid (22%). 12: [R]24
D
+161° (c 0.51, CHCl3). UV (EtOH) λmax (log ꢀ): 248 (4.35) nm.
1
IR (KBr): 3154, 2948, 2869, 1732, 1652, 1620 cm-1. H NMR
(CDCl3): δ 7.77 (1H, d, J ) 10.3 Hz), 5.81 (1H, d, J ) 10.3
Hz), 5.74 (1H, s), 3.02 (1H, dd, J ) 4.3, 13.6 Hz), 2.67 (1H, s),
2.09 (1H, ddd, J ) 5.2, 14.3, 14.3 Hz), 1.39, 1.38, 1.15, 1.08,
0.97, 0.96, 0.95 (each 3H, s). 13C NMR (CDCl3): δ 204.8, 199.4,
183.2, 170.1, 161.8, 127.9, 124.9, 55.7, 52.9, 46.2, 45.4, 44.9,
44.3, 44.0, 41.8, 39.1, 33.8, 33.0, 32.4, 31.7, 30.9, 28.0, 27.9,
23.8, 23.6, 22.7, 21.7, 20.2, 19.7, 18.2. FABMS (NBA, by a VG
analytical ZAB 2SE) m/z: 467 [M + H]+. HRFABMS (by a VG
analytical ZAB 2SE) Calcd for C30H42O4 + H: 467.3161.
Meth yl 3,12-Dioxoolea n a -1,9(11)-d ien -28-oa te (9). A
solution of 54 (145 mg, 0.30 mmol) and phenylselenenyl
chloride (98%) (69 mg, 0.35 mmol) in EtOAc (7 mL) was stirred
at room temperature for 2.5 h. To the stirred mixture was
added water (1.5 mL). After most of the aqueous layer was
removed, THF (2.7 mL) and 30% H2O2 (0.24 mL) were added
to the organic layer. The mixture was stirred at room tem-
perature for 1 h. The mixture was worked up according to the
standard method to give a crude solid (134 mg). The solid was
subjected to flash column chromatography [hexanes-EtOAc
Found: 467.3161. Anal. (Table 1). 15: mp >190 °C dec; [R]25
D
(5:1)] to give 9 as an amorphous solid (96 mg, 67%): [R]23
-16° (c 0.26, CHCl3). UV (EtOH) λmax (log ꢀ): 210 (4.16), 226
D
(4.15), 300 (3.16) nm. IR (KBr): 3200, 2946, 2866, 1692 cm-1
.
+58° (c 0.64, CHCl3). UV (EtOH) λmax (log ꢀ): 240 (4.20) nm.
1H NMR (CDCl3): δ 7.46 (1H, d, J ) 10.1 Hz), 5.82 (1H, d, J
) 10.1 Hz), 3.56 (1H, d, J ) 17.8 Hz), 2.88 (1H, d, J ) 17.8
Hz), 2.65 (1H, s), 2.31 (2H, m), 2.09 (1H, m), 1.44, 1.31, 1.16,
1.10, 0.96, 0.93, 0.76 (each 3H, s). 13C NMR (CDCl3): δ 208.6,
204.8, 181.9, 160.8, 133.8, 129.9, 125.1, 58.0, 52.9, 48.1, 44.8,
44.3, 44.1, 43.4, 41.1, 39.1, 36.7, 35.7, 33.03, 32.95, 32,8, 32.2,
27.7, 26.6, 24.2, 21.8, 20.2, 20.1, 19.2, 18.8. FABMS (NBA, by
a VG analytical ZAB 2SE) m/z: 467 [M + H]+. HRFABMS (by
a VG analytical ZAB 2SE) Calcd for C30H42O4 + H: 467.3161.
Found: 467.3187. Anal. (Table 1).
IR (KBr): 2948, 2872, 1723, 1666, 1598 cm-1 1H NMR
.
(CDCl3): δ 7.33 (1H, d, J ) 10.5 Hz), 6.00 (1H, s), 5.92 (1H, d,
J ) 10.5 Hz), 3.69 (3H, s), 3.04 (1H, ddd, J ) 3.4, 4.6, 13.4
Hz), 2.91 (1H, d, J ) 4.6 Hz), 1.41, 1.31, 1.19, 1.12, 1.01, 1.00,
0.89 (each 3H, s). 13C NMR (CDCl3): δ 203.7, 199.8, 178.4,
171.6, 155.0, 126.1, 123.8, 52.1, 49.8, 48.5, 47.4, 45.8, 44.9, 42.2,
42.0, 36.0, 34.7, 33.5, 33.0, 32.3, 31.7, 30.8, 28.2, 27.3, 27.1,
24.7, 23.3, 22.8, 21.84, 21.81, 18.6. EIMS (70 eV) m/z: 480 [M]+
(99), 465 (100), 446 (42), 405 (27), 315 (41), 244 (44). HREIMS
Calcd for C31H44O4: 480.3240. Found: 480.3238. Anal. (Table
1).
Meth yl 3,11-Dioxou r sa -1,12-d ien -28-oa te (13). 13 was
prepared from 48 according to the same method as for 9 to
give a crystalline solid (93%). An analytically pure sample was
obtained by recrystallization from a mixture of hexanes and
EtOAc (3:1) as crystals: mp 172-174 °C; [R]24D +150° (c 0.49,
CHCl3). UV (EtOH) λmax (log ꢀ): 248 (4.26) nm. IR (KBr): 2973,
2948, 2866, 1726, 1670, 1655, 1610 cm-1. 1H NMR (CDCl3): δ
7.75 (1H, d, J ) 10.3 Hz), 5.82 (1H, d, J ) 10.3 Hz), 5.71 (1H,
s), 3.63 (3H, s), 2.64 (1H, s), 2.47 (1H, d, J ) 11.7 Hz), 2.11
(1H, ddd, J ) 4.6, 14.7, 14.7 Hz), 1.41, 1.33, 1.16, 1.11 (each
3H, s), 0.98 (3H, d, J ) 7.2 Hz), 0.97 (3H, s), 0.89 (3H, d, J )
6.6 Hz). 13C NMR (CDCl3): δ 204.7, 198.8, 177.3, 164.5, 161.8,
130.4, 124.8, 55.5, 53.1, 53.0, 52.1, 47.9, 45.0, 44.9, 44.2, 39.0,
38.82, 38.79, 36.1, 32.5, 30.5, 28.7, 27.8, 24.0, 21.8, 21.3, 21.2,
20.1, 19.4, 18.3, 17.3. EIMS (70 eV) m/z: 480 [M]+ (84), 465
3,12-Dioxoolea n a -1,9(11)-d ien -28-oic Acid (10). A mix-
ture of 9 (82 mg, 0.17 mmol) and LiI (405 mg) in dry DMF (2
mL) was heated under reflux for 7.5 h. To the mixture were
added water and 5% aqueous HCl solution. The mixture was
extracted with a mixture of CH2Cl2 and Et2O (1:2) (three
times). The extract was worked up according to the standard
method to give an amorphous solid (78 mg). The solid was
subjected to flash column chromatography [hexanes-EtOAc
(1:1)] to give 10 as a crystalline solid (54 mg, 68%). An
analytically pure sample was obtained by recrystallization
from a mixture of hexanes and EtOAc (2:1) as colorless
needles: mp >270 °C dec; [R]23 +63° (c 0.42, CHCl3). UV
D
(EtOH) λmax (log ꢀ): 240 (4.14) nm. IR (KBr): 3117, 2973, 2941,
2867, 1734, 1710, 1671, 1639, 1598 cm-1. 1H NMR (CDCl3): δ

4240 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
(19), 421 (15), 397 (100), 257 (38), 217 (39). HREIMS Calcd
for C31H44O4: 480.3240. Found: 480.3239. Anal. (Table 1).
s), 0.90 (6H, s). 13C NMR (CDCl3): δ 205.0, 185.0, 157.9, 147.7,
124.4, 118.6, 49.9, 48.1, 44.7, 44.1, 41.3, 38.6, 36.2, 35.6, 34.4,
33.7, 33.6, 33.2, 31.8, 30.8, 28.5, 28.0, 27.2, 26.9, 26.3, 23.6,
23.4, 21.7, 18.8, 18.7. FABMS (NBA, by a VG analytical ZAB
2SE) m/z: 453 [M + H]+. HRFABMS (by a VG analytical ZAB
2SE) Calcd for C30H44O3 + H: 453.3369. Found: 453.3390.
Anal. (Table 1).
3,11-Dioxou r sa -1,12-d ien -28-oic Acid (14). 14 was pre-
pared from 13 by the similar method as for 10 except that the
reaction time was 1.25 h. The reaction mixture was crystallized
from a mixture of hexanes and EtOAc (2:1) to give 14 as
crystals (58%). An analytically pure sample was obtained by
recrystallization from MeOH as colorless needles: mp >275
3-Oxoolea n -1-en -28-oic Acid (19). 19 was prepared from
3-oxoolean-28-oic acid (56)15 according to the same method as
for 9. The crude solid was subjected to flash column chroma-
tography [hexanes-EtOAc (3:1)] to give 19 as an amorphous
°C dec; [R]24 +157° (c 0.29, CHCl3). UV (EtOH) λmax (log ꢀ):
D
247 (4.17) nm. IR (KBr): 3116, 2983, 2950, 2930, 1720, 1668,
1628 cm-1. 1H NMR (CDCl3): δ 7.74 (1H, d, J ) 10.3 Hz), 5.82
(1H, d, J ) 10.3 Hz), 5.71 (1H, s), 2.65 (1H, s), 2.44 (1H, d, J
) 11.2 Hz), 2.13 (1H, m), 1.41, 1.34, 1.15, 1.08 (each 3H, s),
0.99 (3H, d, J ) 7.2 Hz), 0.97 (3H, s), 0.89 (3H, d, J ) 6.3 Hz).
13C NMR (CDCl3): δ 204.8, 199.0, 183.1, 164.3, 161.7, 130.6,
124.8, 55.4, 52.9, 52.8, 47.7, 45.0, 44.9, 44.2, 39.0, 38.8, 38.7,
36.2, 32.5, 30.4, 28.6, 27.8, 23.7, 21.7, 21.3, 21.1, 20.2, 19.6,
18.2, 17.2. FABMS (NBA, by a VG analytical ZAB 2SE) m/z:
467 [M + H]+. HRFABMS (by a VG analytical ZAB 2SE) Calcd
for C30H42O4 + H: 467.3161. Found: 467.3202. Anal. (Table
1).
solid (68%): [R]24 +30° (c 0.55, CHCl3). UV (EtOH) λmax (log
D
ꢀ): 236 (3.90) nm. IR (KBr): 3200, 2944, 2866, 1729, 1692,
1672 cm-1. 1H NMR (CDCl3): δ 7.11 (1H, d, J ) 10.2 Hz), 5.82
(1H, d, J ) 10.2 Hz), 2.22 (1H, m), 1.13, 1.06, 1.04, 0.99, 0.96,
0.92, 0.88 (each 3H, s). 13C NMR (CDCl3): δ 205.7, 184.9, 159.8,
125.4, 53.5, 48.1, 44.8, 44.7, 42.9, 40.8, 39.7, 37.4, 36.7, 36.5,
34.5, 33.6, 33.4, 32.5, 30.6, 28.5, 28.0, 26.9, 23.6, 23.3, 21.6,
19.2, 17.2, 16.9. FABMS (NBA, by a Micromass ZAB-SE) m/z:
455 [M + H]+. HRFABMS (by a Micromass 70-SE-4F) Calcd
for C30H46O3 + H: 455.3525. Found: 455.3518. Anal. (Table
1).
3,11-Dioxoolea n a -1,13(18)-d ien -28-oic Acid (15). To a
solution of 20 (106 mg, 0.24 mmol) in acetone (6.5 mL) was
added J ones reagent (0.36 mL) dropwise in an ice bath. The
mixture was stirred at room temperature for 30 min. After
removal of acetone, water was added to the resultant mixture.
The aqueous mixture was extracted with CH2Cl2 (three times).
The extract was worked up according to the standard method
to give a solid (80 mg). The solid was subjected to prep-TLC
[hexanes-EtOAc (1.2:1.0)] to give 15 as a crystalline solid (31
mg, 28%).
3-Oxoolea n a -1,11,13(18)-tr ien -28-oic Acid (20). 20 was
prepared from 60 by the similar method as for 10 except that
the reaction time was 4 h. The crude solid was subjected to
prep-TLC [hexanes-EtOAc (2.5:1)] to give 20 as an amorphous
solid (56%): [R]24 -88° (c 0.44, CHCl3). UV (EtOH) λmax (log
D
ꢀ): 246 (4.35), 252 (4.35) nm. IR (KBr): 3167, 3036, 2944, 2863,
1
1727, 1695, 1672 cm-1. H NMR (CDCl3): δ 7.27 (1H, d, J )
10.1 Hz), 6.57 (1H, dd, J ) 2.9, 10.5 Hz), 5.89 (1H, d, J ) 10.1
Hz), 5.81 (1H, dd, J ) 1.5, 10.5 Hz), 2.57 (1H, d, J ) 14.2 Hz),
2.29 (2H, m), 1.174, 1.170, 1.10, 1.00, 0.98, 0.86, 0.82 (each
3H, s). 13C NMR (CDCl3): δ 205.7, 182.8, 159.1, 136.6, 132.5,
126.5, 125.7, 125.4, 53.4, 48.4, 48.3, 45.0, 42.4, 41.6, 40.8, 39.3,
37.0, 35.6, 32.9, 32.7, 32.4, 31.9, 27.7, 25.1, 24.3, 21.32, 21.27,
20.0, 19.2, 16.9. FABMS (NBA, by a VG analytical ZAB 2SE)
m/z: 451 [M + H]+. HRFABMS (by a VG analytical ZAB 2SE)
Calcd for C30H42O3 + H: 451.3212. Found: 451.3240. Anal.
(Table 1).
Meth yl 3,12-Dioxoolea n -1-en -28-oa te (16). 16 was pre-
pared from 51 according to the same method as for 9. The
crude solid was subjected to flash column chromatography
[hexanes-EtOAc (3:1) followed by hexanes-EtOAc (2:1)] to
give 16 as an amorphous solid (75%): [R]24 +2.1° (c 0.39,
D
CHCl3). UV (EtOH) λmax (log ꢀ): 234 (3.85) nm. IR (KBr): 2946,
2867, 1724, 1700, 1671 cm-1. 1H NMR (CDCl3): δ 6.95 (1H, d,
J ) 10.3 Hz), 5.84 (1H, d, J ) 10.3 Hz), 3.70 (3H, s), 2.82 (1H,
ddd, J ) 3.5, 4.2, 13.4 Hz), 2.68 (1H, d, J ) 4.2 Hz), 2.49 (1H,
dd, J ) 4.6, 16.4 Hz), 2.33 (1H, dd, J ) 13.3, 16.4 Hz), 1.16,
1.11, 1.10, 1.06, 0.99, 0.97, 0.91 (each 3H, s). 13C NMR
(CDCl3): δ 210.4, 204.8, 178.5, 157.2, 126.0, 53.4, 52.2, 52.1,
47.5, 44.8, 44.2, 42.4, 42.3, 39.5, 38.6, 36.4, 34.6, 33.5, 33.0,
32.2, 31.6, 30.8, 27.82, 27.76, 23.3, 22.9, 21.6, 20.8, 19.1, 18.5,
16.6. EIMS (70 eV) m/z: 482 [M]+ (5.5), 467 (42), 407 (100),
278 (25), 218 (64). HREIMS Calcd for C31H46O4: 482.3396.
Found: 482.3387. Anal. (Table 1).
9,11-Ep oxy-3-oxoolea n -1-en -28-oic Acid (21). A mixture
of 18 (57 mg, 0.13 mmol) and mCPBA (60%) (43 mg, 0.15
mmol) in CH2Cl2 (3 mL) was stirred at room temperature
overnight. After the mixture was diluted with a mixture of
CH2Cl2 and Et2O (1:2), it was worked up according to the
standard method to give a solid (65 mg). The solid was
subjected to prep-TLC [hexanes-EtOAc (1.5:1)] to give 21 as
a crystalline solid (27 mg, 46%). An analytically pure sample
was obtained by recrystallization from MeOH as colorless
needles: mp 253-254 °C; [R]24 -14° (c 0.25, CHCl3). UV
3,12-Dioxoolea n -1-en -28-oic Acid (17). 17 was prepared
from 16 by the similar method as for 10 except that the
reaction time was 4.5 h. The crude material was subjected to
prep-TLC [hexanes-EtOAc (1:2)] to give 17 as a crystalline
D
(EtOH) λmax (log ꢀ): 236 (3.88) nm. IR (KBr): 2970, 2945, 1688
cm-1. 1H NMR (CDCl3): δ 6.55 (1H, d, J ) 10.4 Hz), 5.85 (1H,
d, J ) 10.4 Hz), 3.02 (1H, s), 1.39 (3H, s), 1.07 (6H, s), 1.04,
0.96, 0.92, 0.87 (each 3H, s). 13C NMR (CDCl3): δ 204.5, 184.4,
154.4, 125.2, 67.8, 60.2, 47.9, 45.3, 44.9, 42.3, 41.5, 38.4, 37.3,
35.7, 34.3, 33.6, 33.3, 30.8, 30.0, 28.2, 27.9, 26.9, 24.9, 23.6,
23.3, 21.1, 20.6, 18.7, 18.6. FABMS (NBA, by a VG analytical
ZAB 2SE) m/z: 469 [M + H]+. HRFABMS (by a VG analytical
ZAB 2SE) Calcd for C30H44O4 + H: 469.3318. Found: 469.3314.
Anal. (Table 1).
solid (62%): mp 243-245 °C dec; [R]24 +2.3° (c 0.27, CHCl3).
D
UV (EtOH) λmax (log ꢀ): 234 (3.89) nm. IR (KBr): 3166, 2946,
1
2866, 1722, 1696, 1668, 1651 cm-1. H NMR (CDCl3): δ 6.96
(1H, d, J ) 10.4 Hz), 5.84 (1H, d, J ) 10.4 Hz), 2.79 (2H, m),
2.51 (1H, dd, J ) 4.9, 15.9 Hz), 2.35 (1H, dd, J ) 13.2, 15.9
Hz), 1.17, 1.11 (each 3H, s), 1.10 (6H, s), 1.00, 0.98, 0.93 (each
3H, s). 13C NMR (CDCl3): δ 210.2, 204.9, 184.2, 157.2, 126.0,
53.3, 52.2, 47.4, 44.8, 44.1, 42.4, 42.3, 39.5, 38.6, 36.2, 34.6,
33.5, 33.2, 32.0, 31.6, 30.8, 27.8, 23.3, 22.8, 21.6, 20.7, 19.1,
18.5, 16.7. EIMS (70 eV) m/z: 468 [M]+ (9.7), 453 (15), 407
(39), 218 (19), 83 (100). HREIMS Calcd for C30H44O4: 468.3240.
Found: 468.3221. Anal. (Table 1).
3,11-Dioxoolea n a -1,12-d ien -28-yl Aceta te (22). 22 was
prepared from 3,11-dioxoolean-12-en-28-yl acetate (61)18 ac-
cording to the same method as for 9. The crude solid was
subjected to prep-TLC [hexanes-EtOAc (3:1)] to give 22 as
an amorphous solid (83%): [R]24 +131° (c 0.45, CHCl3). UV
D
3-Oxoolea n a -1,9(11)-d ien -28-oic Acid (18). 18 was pre-
pared from 58 according to the same method as for 9. The
crude solid was subjected to prep-TLC [hexanes-EtOAc (2:
1)] to give 18 as a crystalline solid (80%). An analytically pure
sample was obtained by recrystallization from MeOH as
colorless needles: mp >240 °C dec; [R]24D +55° (c 0.28, CHCl3).
UV (EtOH) λmax (log ꢀ): 234 (3.93) nm. IR (KBr): 3138, 3053,
2959, 2930, 2869, 1727, 1693, 1645 cm-1. 1H NMR (CDCl3): δ
7.42 (1H, d, J ) 10.4 Hz), 5.85 (1H, d, J ) 10.4 Hz), 5.63 (1H,
t, J ) 3.4 Hz), 1.35, (3H, s), 1.16 (6H, s), 1.07, 0.94 (each 3H,
(EtOH) λmax (log ꢀ): 246 (4.31) nm. IR (KBr): 2949, 2868, 1742,
1665 cm-1. 1H NMR (CDCl3): δ 7.72 (1H, d, J ) 10.1 Hz), 5.79
(1H, d, J ) 10.1 Hz), 5.67 (1H, s), 3.97 (1H, d, J ) 11.2 Hz),
3.71 (1H, d, J ) 11.2 Hz), 2.66 (1H, s), 2.29 (1H, dd, J ) 4.2,
13.2 Hz), 2.07 (3H, s), 2.03 (1H, ddd, J ) 4.4, 13.9, 13.9 Hz),
1.404, 1.397, 1.18, 1.15, 1.11, 0.93, 0.91 (each 3H, s). 13C NMR
(CDCl3): δ 204.7, 198.9, 171.2, 170.2, 161.7, 128.3, 124.8, 70.3,
55.8, 53.0, 45.7, 44.99, 44.96, 43.8, 42.9, 39.0, 36.0, 33.9, 33.0,
32.1, 31.2, 31.0, 27.8, 26.1, 23.7, 23.5, 22.1, 21.7, 21.1, 20.2,
19.0, 18.3. EIMS (70 eV) m/z: 494 [M]+ (100), 446 (92), 411

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4241
(41), 406 (37), 351 (19). HREIMS Calcd for C32H46O4: 494.3396.
Found: 494.3396. Anal. (Table 1).
benzene completely, the crystals were dissolved in CH2Cl2 (20
mL) and the solvent was evaporated in vacuo to give benzene-
free 26 as an amorphous solid (405 mg, 68%): [R]22 +33 ° (c
D
28-Hyd r oxyolea n a -1,12-d ien e-3,11-d ion e (23). A solution
of 22 (47 mg, 0.095 mmol) and KOH (300 mg) in MeOH (3
mL) was stirred at room temperature for 20 min. The mixture
was acidified with 5% aqueous HCl solution. The aqueous
mixture was extracted with a mixture of CH2Cl2 and Et2O (1:
2) (three times). The extract was worked up according to the
standard method to give an amorphous solid (42 mg). The solid
was subjected to prep-TLC [hexanes-EtOAc (1.7:1)] to give
0.28, CHCl3). UV (EtOH) λmax (log ꢀ): 240 (4.21) nm. IR
1
(KBr): 2950, 2867, 2235, 1692, 1665 cm-1. H NMR (CDCl3):
δ 8.05 (1H, s), 6.00 (1H, s), 3.06-2.98 (2H, m), 1.48, 1.34, 1.25,
1.16, 1.02, 1.00, 0.90 (each 3H, s). 13C NMR (CDCl3): δ 199.0,
196.8, 183.7, 168.8, 165.9, 124.2, 114.7, 114.5, 49.8, 47.8, 47.1,
45.9, 45.2, 42.7, 42.3, 35.8, 34.5, 33.3, 33.0, 31.8, 31.5, 30.8,
28.1, 27.1, 26.8, 24.8, 23.2, 22.6, 21.72, 21.71, 18.4. EIMS (70
eV) m/z: 491 [M]+ (100), 476 (62), 445 (29), 430 (27), 269 (94).
HREIMS Calcd for C31H41O4N: 491.3036. Found: 491.3020.
Anal. (Table 1).
23 as an amorphous solid (34 mg, 78%): [R]24 +145° (c 0.50,
D
CHCl3). UV (EtOH) λmax (log ꢀ): 250 (4.13) nm. IR (KBr): 3477,
1
2947, 2865, 1660 cm-1. H NMR (CDCl3): δ 7.72 (1H, d, J )
10.3 Hz), 5.80 (1H, d, J ) 10.3 Hz), 5.67 (1H, s), 3.48 (1H, d,
J ) 11.0 Hz), 3.25 (1H, d, J ) 11.0 Hz), 2.67 (1H, s), 2.21 (1H,
dd, J ) 3.8, 13.6 Hz), 1.97 (1H, ddd, J ) 4.4, 13.7, 13.7 Hz),
1.41, 1.40 (each 3H, s), 1.16 (6H, s), 1.11, 0.93, 0.91 (each 3H,
s). 13C NMR (CDCl3): δ 204.8, 199.1, 171.4, 161.8, 128.0, 124.8,
69.8, 55.7, 53.0, 45.8, 45.1, 45.0, 43.9, 43.0, 39.0, 37.2, 34.0,
33.1, 32.2, 31.3, 30.8, 27.8, 26.1, 23.6, 21.8, 21.7, 20.3, 19.0,
18.4. EIMS (70 eV) m/z: 452 [M]+ (100), 437 (15), 434 (16),
383 (16), 364 (50), 248 (46). HREIMS Calcd for C30H44O3:
452.3290. Found: 452.3292. Anal. (Table 1).
Meth yl 2-Meth oxyca r bon yl-3,12-d ioxoolea n a -1,9(11)-
d ien -28-oa te (27). To a solution of phenylselenenyl chloride
(98%) (78 mg, 0.40 mmol) in CH2Cl2 (3.2 mL) in an ice bath
was added a solution of pyridine (35 mg, 0.44 mmol) in CH2-
Cl2 (0.8 mL). After 15 min, a solution of 71 (108 mg, 0.20 mmol)
in CH2Cl2 (1.4 mL) was added and the mixture was stirred an
additional 1 h. After the mixture was washed with 10%
aqueous HCl solution (1.6 mL) twice, 30% H2O2 (0.2 mL) was
added to the stirred mixture in the ice bath. After an additional
40 min, the mixture was worked up according to the standard
method to give a solid (108 mg). The solid was subjected to
flash column chromatography [hexanes-EtOAc (2:1)] to afford
71 (21 mg) and 27 as colorless needles (76 mg; 71%, 88% based
on recovered 71): mp 187-188 °C; [R]23D +35° (c 0.38, CHCl3).
UV (EtOH) λmax (log ꢀ): 246 (4.06) nm. IR (KBr): 2944, 2867,
Olea n a -1,12-d ien e-3,11,28-tr ion e (24). To a stirred mix-
ture of CrO3 (70 mg, 0.70 mmol) and pyridine (110 mg, 1.39
mmol) in dry CH2Cl2 (2 mL) was added a solution of 23 (53
mg, 0.12 mmol) in dry CH2Cl2 (1.5 mL). The mixture was
stirred at room temperature for 15 min. The mixture was
worked up according to Ratcliffe’s procedure20 to give a crude
solid of 24 (47 mg, 89%). The solid was recrystallized from a
mixture of hexanes and EtOAc (2:1) to give 24 as colorless
1
1722, 1664, 1597 cm-1. H NMR (CDCl3): δ 8.05 (1H, s), 6.09
(1H, s), 3.79, 3.69 (each 3H, s), 3.04 (1H, ddd, J ) 3.5, 4.5,
13.9 Hz), 2.94 (1H, d, J ) 4.5 Hz), 1.37, 1.30, 1.18, 1.17, 1.01,
0.99, 0.88 (each 3H, s). 13C NMR (CDCl3): δ 199.6, 199.4, 178.3,
170.8, 165.0, 160.7, 129.9, 125.2, 52.5, 52.1, 50.0, 48.3, 47.4,
46.0, 45.8, 42.3, 42.0, 36.0, 34.6, 33.4, 32.9, 31.7, 30.8, 28.2,
28.1, 27.3, 24.6, 23.3, 22.8, 21.7, 21.4, 18.8. EIMS (70 eV) m/z:
538 [M]+ (20), 523 (40), 506 (100), 315 (47). HREIMS Calcd
for C33H46O6: 538.3294. Found: 538.3289. Anal. (Table 1).
needles (31 mg, 59%): mp >267 °C dec; [R]24 +160° (c 0.27,
D
CHCl3). UV (EtOH) λmax (log ꢀ): 248 (4.15) nm. IR (KBr): 2944,
2864, 1719, 1674, 1644 cm-1 1H NMR (CDCl3): δ 9.40 (1H,
.
s), 7.76 (1H, d, J ) 10.3 Hz), 5.80 (1H, d, J ) 10.3 Hz), 5.77
(1H, s), 2.84 (1H, dd, J ) 4.3, 13.6 Hz), 2.64 (1H, s), 2.10 (1H,
ddd, J ) 3.9, 14.3, 14.3 Hz), 1.38 (6H, s), 1.15, 1.10 (each 3H,
s), 0.96 (6H, s), 0.93 (3H, s). 13C NMR (CDCl3): δ 205.4, 204.7,
199.0, 169.1, 161.7, 128.0, 124.8, 55.7, 53.0, 49.1, 45.4, 44.9,
44.3, 43.9, 40.1, 39.1, 33.2, 32.9, 32.4, 30.9, 27.9, 27.30, 27.26,
23.5, 23.3, 21.7, 21.6, 20.1, 19.6, 18.3. EIMS (70 eV) m/z: 450
[M]+ (100), 446 (64), 367 (45), 362 (31), 246 (36). HREIMS
Calcd for C30H42O3: 450.3134. Found: 450.3129. Anal. (Table
1).
2-Meth oxyca r bon yl-3,12-d ioxoolea n a -1,9(11)-d ien -28-
oic Acid (28). A solution of 30 (33 mg, 0.064 mmol) in MeOH
(3.1 mL) containing concentrated H2SO4 (0.09 mL) was heated
under reflux for 25 min. After water was added to the mixture,
it was extracted with EtOAc (three times). The extract was
worked up according to the standard method to give a solid
(31 mg). The solid was a mixture of 28 and 3-hydroxy-1-meth-
oxy-2-methoxycarbonyl-12-oxooleana-2,9(11)-dien-28-oic acid
(72). The solid was subjected to prep-TLC [hexanes-EtOAc
(1:1)] to give only 28 as a crystalline solid (27 mg, 82%). An
analytically pure sample was obtained by recrystallization
from a mixture of hexanes and EtOAc (2:1) as colorless
Meth yl 2-Cya n o-3,12-d ioxoolea n a -1,9(11)-d ien -28-oa te
(25). A mixture of 64 (1.51 g, 2.97 mmol) and DDQ (98%) (0.77
g, 3.32 mmol) in dry benzene (80 mL) was heated under reflux
for 30 min. After insoluble matter was removed by filtration,
the filtrate was evaporated in vacuo to give a solid. The solid
was subjected to flash column chromatography [benzene-
acetone (10:1)] to give 25 as an amorphous solid (1.38 g,
92%): [R]23D +33° (c 0.68, CHCl3). UV (EtOH) λmax (log ꢀ): 244
needles: mp >265 °C dec; [R]23 +34° (c 0.42, CHCl3). UV
D
(EtOH) λmax (log ꢀ): 240 (4.09) nm. IR (KBr): 3118, 2977, 2940,
2869, 1718, 1692, 1636 cm-1 1H NMR (CDCl3): δ 8.06 (1H,
.
(4.07) nm. IR (KBr): 2950, 2872, 2233, 1722, 1690, 1665 cm-1
.
s), 6.11 (1H, s), 3.81 (3H, s), 3.09-2.98 (2H, m), 1.38, 1.34,
1.20, 1.19, 1.04, 1.02, 0.91 (each 3H, s). 13C NMR (CDCl3): δ
199.7, 199.2, 183.5, 170.9, 165.1, 160.7, 130.0, 125.3, 52.6, 50.0,
48.3, 47.2, 46.0, 45.9, 42.3, 42.0, 35.9, 34.6, 33.4, 33.1, 31.7,
31.6, 30.8, 28.2, 28.1, 27.3, 24.7, 23.2, 22.7, 21.7, 21.4, 18.8.
EIMS (70 eV) m/z: 524 [M]+ (17), 509 (24), 492 (100), 446 (38),
302 (31). HREIMS Calcd for C32H44O6: 524.3138. Found:
524.3142. Anal. (Table 1). 72:34 1H NMR (CDCl3): δ 13.06 (1H,
s), 5.93 (1H, s), 4.46 (1H, s), 3.82 (3H, s), 3.21 (3H, s), 3.03
(2H, m), 2.12 (1H, dd, J ) 3.8, 10.4 Hz), 1.26, 1.22, 1.13, 1.07,
1.05, 1.02, 0.92 (each 3H, s). 13C NMR (CDCl3): δ 200.2, 184.1,
182.1, 174.8, 174.0, 124.4, 96.9, 57.3, 51.9, 50.1, 47.4, 46.0, 45.7,
44.7, 42.8, 41.5, 39.5, 36.1, 34.7, 33.4, 33.2, 31.7, 31.2, 30.9,
28.5, 24.3, 23.8, 23.3, 23.2, 22.8, 21.2, 20.9, 18.5. EIMS (70
eV) m/z: 556 [M]+ (3.0), 538 (54), 524 (61), 509 (35), 492 (96),
446 (86), 315 (100). HREIMS Calcd for C33H48O7: 556.3400.
Found: 556.3410.
1H NMR (CDCl3): δ 8.04 (1H, s), 5.96 (1H, s), 3.68 (3H, s),
3.02 (1H, ddd, J ) 3.4, 4.9, 13.4 Hz), 2.92 (1H, d, J ) 4.9 Hz),
1.47, 1.31, 1.24, 1.15, 0.99, 0.98, 0.88 (each 3H, s). 13C NMR
(CDCl3): δ 199.0, 196.8, 178.3, 168.6, 165.9, 124.2, 114.7, 114.6,
52.1, 49.8, 47.8, 47.3, 45.9, 45.2, 42.7, 42.2, 35.9, 34.6, 33.4,
32.9, 31.8, 31.6, 30.8, 28.1, 27.1, 26.8, 24.7, 23.2, 22.7, 21.8,
21.7, 18.4. EIMS (70 eV) m/z: 505 [M]+ (100), 490 (81), 430
(42), 315 (47), 269 (40). HREIMS Calcd for C32H43O4N:
505.3192. Found: 505.3187. Anal. (Table 1).
2-Cya n o-3,12-d ioxoolea n a -1,9(11)-d ien -28-oic Acid (26).
A mixture of 25 (612 mg, 1.21 mmol) and LiI (3.0 g) in dry
DMF (10 mL) was heated under reflux for 4 h. To the mixture
were added water and 5% aqueous HCl solution. The mixture
was extracted with EtOAc (three times). The extract was
washed with water (three times) and saturated aqueous NaCl
solution (three times), dried over MgSO4, and filtered. The
filtrate was evaporated in vacuo to give an amorphous solid.
The solid was subjected to flash column chromatography
[hexanes-EtOAc (1:1) followed by CH2Cl2-MeOH (15:1)] to
give crude 26 (530 mg). The crude product was purified by
recrystallization from benzene to give crystals. To remove
Met h yl 2-Ca r b oxy-3,12-d ioxoolea n a -1,9(11)-d ien -28-
oa te (29). A mixture of 27 (273 mg, 0.51 mmol) and KOH (1.6
g) in water (5.3 mL) and MeOH (16 mL) was heated under
reflux for 15 min. After the mixture was acidified with 10%
aqueous HCl solution, it was extracted with EtOAc (three

4242 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
times). The extract was washed with water (three times) and
saturated aqueous NaCl solution (three times), dried over
MgSO4, and filtered. The filtrate was evaporated in vacuo to
give a solid (264 mg). The solid was recrystallized from MeOH
to afford 29 as colorless needles (174 mg). The solid (75 mg)
which was obtained from the mother liquid was subjected to
flash column chromatography [hexanes-EtOAc (1:1)] to give
9 (19 mg, 8%) and 29 as colorless needles (33 mg, total 78%):
18.7. EIMS (70 eV) m/z: 491 [M]+ (5.3), 461 (55), 445 (100),
351 (38), 310 (29), 257 (50). HREIMS Calcd for C32H41O4N:
491.3036. Found: 491.3040. Anal. (Table 1).
Meth yl 2-Cya n o-3,11-d ioxou r sa -1,12-d ien -28-oa te (33).
33 was prepared from 70 according to the same method as for
25 to give a crystalline solid (90%): mp >275 °C dec; [R]25
D
+91° (c 0.36, CHCl3). UV (EtOH) λmax (log ꢀ): 250 (4.22) nm.
IR (KBr): 2984, 2937, 2866, 2232, 1725, 1687, 1658, 1614 cm-1
.
mp 155-156 °C dec; [R]23 +50° (c 0.30, CHCl3). UV (EtOH)
1H NMR (500 MHz, by a Varian Unityplus, CDCl3): δ 8.55
(1H, s), 5.74 (1H, s), 3.63 (3H, s), 2.68 (1H, s), 2.49 (1H, d, J )
11.5 Hz), 2.12 (1H, m), 1.44, 1.34, 1.21, 1.15 (each 3H, s), 0.99
(3H, d, J ) 6.4 Hz), 0.97 (3H, s), 0.89 (3H, d, J ) 6.4 Hz). 13C
NMR (125.705 MHz, by a Varian Unityplus, CDCl3): δ 197.9,
197.8, 177.2, 172.9, 165.6, 130.1, 115.1, 113.5, 54.2, 53.1, 52.1,
52.0, 47.8, 45.2, 45.1, 44.4, 39.9, 38.8, 36.0, 32.1, 30.4, 28.6,
27.8, 24.0, 21.7, 21.2, 21.1, 19.6, 19.4, 18.2, 17.3. EIMS (70
eV) m/z: 505 [M]+ (62), 490 (15), 446 (19), 445 (19), 430 (23),
411 (47), 256 (37), 217 (37), 189 (69), 119 (100). HREIMS Calcd
for C32H43O4N: 505.3192. Found: 505.3200. Anal. (Table 1).
D
λmax (log ꢀ): 254 (4.14) nm. IR (KBr): 2950, 2872, 1756, 1722,
1664 cm-1. 1H NMR (CDCl3): δ 8.77 (1H, s), 6.17 (1H, s), 3.70
(3H, s), 3.04 (1H, ddd, J ) 3.6, 4.5, 13.2 Hz), 2.92 (1H, d, J )
4.5 Hz), 1.48, 1.34, 1.29, 1.22 (each 3H, s), 1.00 (6H, s), 0.90
(3H, s). 13C NMR (CDCl3): δ 207.6, 199.1, 178.4, 169.1, 168.5,
164.3, 124.5, 123.8, 52.1, 49.9, 47.7, 47.4, 45.9, 45.7, 42.5, 42.2,
35.9, 34.6, 33.4, 32.9, 31.8, 31.7, 30.8, 28.2, 27.5, 27.1, 24.8,
23.2, 22.8, 22.0, 21.8, 18.5. EIMS (70 eV) m/z: 524 [M]+ (12),
509 (31), 506 (74), 480 (52), 465 (83), 405 (56), 315 (66), 175
(100). HREIMS Calcd for C32H44O6: 524.3138. Found: 524.3138.
Anal. (Table 1).
2-Cya n o-3,11-d ioxou r sa -1,12-d ien -28-oic Acid (34).35
A
2-Ca r b oxy-3,12-d ioxoolea n a -1,9(11)-d ien -28-oic Acid
(30).35 A mixture of 29 (120 mg, 0.23 mmol) and LiI (545 mg)
in dry DMF (1.6 mL) was heated under reflux for 30 min. The
reaction mixture was worked up according to the same method
as for 26 to give a solid (125 mg). The solid was recrystallized
from a mixture of hexanes and EtOAc (1:2) to afford 30 as
colorless needles (36 mg). The solid which was obtained from
the mother liquid was subjected to flash column chromatog-
raphy [hexanes-EtOAc (1:2)] to give 10 (26 mg, 24%) and 30
mixture of 33 (155 mg, 0.31 mmol) and LiI (750 mg) in dry
DMF (2.4 mL) was heated under reflux for 1.5 h. The reaction
mixture was poured into water to give a solid. The solid was
filtered and washed with water (several times). The crude solid
(140 mg) was crystallized from a mixture of hexanes and
EtOAc (2:1) to give 34 as crystals (90 mg, 60%). An analytically
pure sample was obtained by crystallization from a mixture
of CH2Cl2 and MeOH as crystals: mp >285 °C dec; [R]25
D
+119° (c 0.25, DMSO). UV (DMSO) λmax (log ꢀ): 264 (4.16) nm.
as colorless needles (19 mg, total 47%): mp >260 °C dec; [R]24
D
IR (KBr): 3117, 3050, 2983, 2951, 2930, 2873, 2231, 1719,
+52° (c 0.28, CHCl3). UV (EtOH) λmax (log ꢀ): 256 (4.17) nm.
1685, 1624 cm-1 1H NMR [DMSO-d6, internal standard: δ
.
IR (KBr): 3269, 2956, 2928, 1750, 1728, 1658, 1631, 1595 cm-1
.
2.50 (CD2HSOCD3)]: δ 8.49 (1H, s), 5.54 (1H, s), 2.95 (1H, s),
2.33 (1H, d, J ) 11.2 Hz), 2.11 (1H, dd, J ) 3.9, 13.2, 13.2
Hz), 1.35, 1.30, 1.13, 1.06 (each 3H, s), 0.942 (3H, d, J ) 4.2
Hz), 0.935 (3H, s), 0.84 (3H, d, J ) 6.4 Hz). EIMS (70 eV) m/z:
465 [M - CN]+ (36), 446 [M - CO2H]+ (100), 420 (4.0), 405
(11), 315 (17), 244 (19). HREIMS Calcd for C31H41O4N - CN:
465.3005. Found: 465.3010. Calcd for C31H41O4N - CO2H:
446.3059. Found: 446.3060. Anal. (Table 1).
1H NMR (CDCl3): δ 8.77 (1H, s), 6.18 (1H, s), 3.04 (1H, ddd,
J ) 3.5, 4.9, 13.6 Hz), 2.98 (1H, d, J ) 4.9 Hz), 1.48, 1.36,
1.30, 1.23 (each 3H, s), 1.02 (6H, s), 0.91 (3H, s). EIMS (70
eV) m/z: 510 [M]+ (12), 492 (100), 466 (71), 451 (75), 405 (48),
301 (37). HREIMS Calcd for C31H42O6: 510.2981. Found:
510.2979. Anal. (Table 1).
Meth yl 2-Cyan o-3,11-dioxoolean a-1,12-dien -28-oate (31).
31 was prepared from 67 according to the same method as for
Meth yl 2-Am in ocar bon yl-3,12-dioxoolean a-1,9(11)-dien -
28-oa te (36). A solution of 27 (41.5 mg, 0.78 mmol) in
saturated ammonia MeOH (4 mL) was kept at room temper-
ature overnight. The mixture was evaporated in vacuo to give
a residue (41 mg). The residue was subjected to flash column
chromatography [hexanes-EtOAc (1:1.5)] to give 27 (18.5 mg)
and 36 as an amorphous solid (19.6 mg; 49%, 88% based on
25 to give an amorphous solid (80%): [R]24 +97° (c 0.49,
D
CHCl3). UV (EtOH) λmax (log ꢀ): 250 (4.24) nm. IR (KBr): 2944,
2867, 2233, 1726, 1686, 1656, 1617 cm-1. 1H NMR (CDCl3): δ
8.59 (1H, s), 5.77 (1H, s), 3.65 (3H, s), 3.06 (1H, dd, J ) 4.0,
13.7 Hz), 2.69 (1H, s), 2.08 (1H, ddd, J ) 4.1, 13.6, 13.6 Hz),
1.41, 1.38, 1.21, 1.15, 0.97, 0.96, 0.95 (each 3H, s). 13C NMR
(CDCl3): δ 198.4, 197.8, 177.5, 173.0, 171.5, 127.3, 115.1, 113.5,
54.5, 52.2, 52.0, 46.3, 45.5, 45.3, 44.4, 44.1, 42.1, 40.0, 33.8,
33.0, 31.9, 31.6, 30.9, 28.0, 27.8, 23.8, 23.6, 23.0, 21.7, 19.6,
19.4, 18.2. EIMS (70 eV) m/z: 505 [M]+ (100), 445 (22), 417
(27), 370 (20). HREIMS Calcd for C32H43O4N: 505.3192.
Found: 505.3200. Anal. (Table 1).
recovered 27): [R]24 +42° (c 0.36, CHCl3). UV (EtOH) λmax
D
(log ꢀ): 242 (4.23) nm. IR (KBr): 3433, 3334, 2949, 2871, 1725,
1
1692, 1666 cm-1. H NMR (CDCl3): δ 8.64 (1H, s), 8.35 (1H,
d, J ) 3.3 Hz), 6.22 (1H, s), 5.73 (1H, d, J ) 3.3 Hz), 3.69 (3H,
s), 3.05 (1H, ddd, J ) 3.7, 4.5, 13.2 Hz), 2.92 (1H, d, J ) 4.5
Hz), 1.41, 1.32 (each 3H, s), 1.20, 1.01 (each 6H, s), 0.90 (3H,
s). 13C NMR (CDCl3): δ 204.4, 199.2, 178.5, 169.9, 165.3, 164.8,
127.8, 125.1, 52.1, 50.0, 47.8, 47.4, 46.2, 45.8, 42.2, 42.0, 35.9,
34.7, 33.4, 33.0, 31.73, 31.70, 30.8, 28.4, 28.2, 27.7, 24.7, 23.3,
22.9, 21.9, 21.8, 18.8. EIMS (70 eV) m/z: 523 [M]+ (2.2), 508
(9.1), 506 (21), 446 (9.6), 315 (6.9), 84 (100). HREIMS Calcd
for C32H45O5N: 523.3298. Found: 523.3292. Anal. (Table 1).
2-Cya n o-3,11-d ioxoolea n a -1,12-d ien -28-oic Acid (32)35
a n d 2-Cya n o-3,11-d ioxoolea n a -1,13(18)-d ien -28-oic Acid
(35). 32 and 35 were prepared from 31 by the similar method
as for 26. The reaction mixture was subjected to prep-TLC
[hexanes-EtOAc-MeOH (50:100:1.5)] to give 32 as a crystal-
line solid (37%) and 35 as an amorphous solid (16%). 32: mp
>270 °C dec; [R]24D +101° (c 0.28, CHCl3). UV (EtOH) λmax (log
ꢀ): 250 (4.23) nm. IR (KBr): 3228, 2944, 2867, 2233, 1732,
Meth yl 2-F or m yl-3,12-d ioxoolea n a -1,9(11)-d ien -28-oa te
(37). 37 was prepared from 62 according to the same method
as for 27 to give an amorphous solid (62%, 74% based on
1
1689, 1656 cm-1. H NMR (CDCl3): δ 8.58 (1H, s), 5.78 (1H,
s), 3.04 (1H, dd, J ) 3.7, 13.9 Hz), 2.69 (1H, s), 2.11 (1H, ddd,
J ) 3.9, 13.7, 13.7 Hz), 1.42, 1.40, 1.22, 1.14, 1.00, 0.973, 0.968
(each 3H, s). EIMS (70 eV) m/z: 491 [M]+ (34), 445 (31), 397
(26), 257 (36), 189 (59), 95 (100). HREIMS Calcd for
recovered 62): [R]24 -3.7° (c 0.39, CHCl3). UV (EtOH) λmax
D
(log ꢀ): 254 (4.05) nm. IR (KBr): 2944, 2867, 1722, 1704, 1668,
1611 cm-1. 1H NMR (CDCl3): δ 10.02 (1H, s), 8.11 (1H, s), 6.14
(1H, s), 3.70 (3H, s), 3.05 (1H, ddd, J ) 3.7, 4.5, 13.2 Hz), 2.93
(1H, d, J ) 4.5 Hz), 1.44, 1.33, 1.23, 1.19 (each 3H, s), 1.00
(6H, s), 0.89 (3H, s). 13C NMR (CDCl3): δ 202.2, 199.3, 189.8,
178.4, 169.9, 161.4, 131.5, 124.7, 52.1, 49.9, 48.2, 47.4, 46.0,
45.4, 42.3, 42.1, 36.0, 34.7, 33.4, 33.0, 31.9, 31.7, 30.8, 28.2,
27.5, 27.2, 24.7, 23.3, 22.8, 21.8, 21.6, 18.7. EIMS (70 eV) m/z:
508 [M]+ (37), 493 (35), 446 (44), 315 (28), 84 (100). HREIMS
Calcd for C32H44O5: 508.3189. Found: 508.3183. Anal. (Table
1).
C
31H41O4N: 491.3036. Found: 491.3034. Anal. (Table 1). 35:
[R]25D -1.7° (c 0.47, CHCl3). UV (EtOH) λmax (log ꢀ): 210 (3.94),
240 (4.02), 304 (2.89) nm. IR (KBr): 3178, 2948, 2867, 2234,
1726, 1694, 1611 cm-1. H NMR (CDCl3): δ 8.25 (1H, s), 3.60
1
(1H, d, J ) 19.2 Hz), 2.91 (1H, d, J ) 19.2 Hz), 2.68 (1H, s),
1.47, 1.30, 1.22, 1.15, 0.97, 0.94, 0.77 (each 3H, s). 13C NMR
(CDCl3): δ 208.2, 197.7, 182.0, 171.8, 133.0, 130.5, 115.1, 113.9,
56.9, 52.0, 48.1, 45.2, 44.2, 44.0, 43.5, 41.1, 40.0, 36.7, 35.7,
33.1, 32.8, 32.4, 32.2, 27.6, 26.5, 24.2, 21.8, 20.1, 19.6, 19.3,

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4243
Meth yl 3â-Hyd r oxy-11-oxou r s-12-en -28-oa te (47). A so-
lution of methyl 3â-acetoxy-11-oxours-12-en-28-oate (46)10 (150
mg, 0.29 mmol) and KOH (1.0 g) in MeOH (10 mL) was heated
under reflux for 30 min. After removal of MeOH in vacuo, the
resultant mixture was acidified with 6 M aqueous HCl
solution. The aqueous layer was extracted with a mixture of
CH2Cl2 and Et2O (1:2) (three times). The extract was worked
up according to the standard method to give 47 as an
amorphous solid (138 mg, quantitative): UV (EtOH) λmax (log
ꢀ): 250 (4.17) nm. IR (KBr): 3494, 2928, 2869, 1728, 1660
(4.03) nm. IR (KBr): 3549, 3382, 2941, 2865, 1717, 1706, 1654,
1
1644, 1595 cm-1. H NMR (CDCl3): δ 5.75 (1H, s), 3.68 (3H,
s), 3.21 (1H, dd, J ) 4.8, 11.4 Hz), 3.02 (1H, ddd, J ) 3.5, 4.6,
13.4 Hz), 2.84 (1H, d, J ) 4.6 Hz), 1.23, 1.18, 1.03 (each 3H,
s), 0.99 (6H, s), 0.89, 0.83 (each 3H, s). 13C NMR (CDCl3): δ
200.8, 178.6, 178.5, 122.9, 78.2, 52.0, 50.4, 49.6, 47.5, 45.5, 41.9,
40.2, 39.4, 36.6, 36.0, 34.7, 33.5, 33.1, 33.0, 31.7, 30.8, 28.3,
27.7, 24.0, 23.9, 23.3, 22.9, 22.0, 18.2, 15.8. EIMS (70 eV) m/z:
484 [M]+ (4.7), 469 (33), 409 (61), 407 (85), 315 (16), 278 (36),
218 (100). HREIMS Calcd for C31H48O4: 484.3553. Found:
484.3553.
1
cm-1. H NMR (CDCl3): δ 5.59 (1H, s), 3.60 (3H, s), 3.21 (1H,
dd, J ) 5.9, 10.6 Hz), 2.78 (1H, ddd, J ) 3.5, 3.5, 13.6 Hz),
2.41 (1H, d, J ) 11.4 Hz), 2.29 (1H, s), 2.07 (1H, m), 1.29, 1.11,
0.99 (each 3H, s), 0.96 (3H, d, J ) 6.2 Hz), 0.90 (3H, s), 0.86
(3H, d, J ) 6.2 Hz), 0.79 (3H, s). 13C NMR (CDCl3): δ 200.1,
177.4, 163.0, 130.9, 78.9, 61.7, 55.2, 52.9, 52.0, 47.9, 44.8, 43.9,
39.34, 39.28, 38.82, 38.77, 37.3, 36.2, 33.2, 30.5, 28.6, 28.3, 27.5,
24.1, 21.3, 21.2, 19.0, 17.6, 17.3, 16.4, 15.8. EIMS (70 eV) m/z:
484 [M]+ (40), 317 (100), 276 (48), 257 (34). HREIMS Calcd
for C31H48O4: 484.3553. Found: 484.3552. This material was
used for the next reaction without further purification.
Meth yl 3,12-Dioxoolea n -9(11)-en -28-oa te (54). 54 was
prepared from 53 according to the same method as for 48 to
give an amorphous solid (92%). An analytically pure sample
was obtained by flash column chromatography [hexanes-
EtOAc (3:1)]: UV (EtOH) λmax (log ꢀ): 250 (3.74) nm. IR
(KBr): 2944, 2867, 1722, 1708, 1661, 1594 cm-1 1H NMR
.
(CDCl3): δ 5.80 (1H, s), 3.70 (3H, s), 3.04 (1H, ddd, J ) 3.3,
4.9, 13.2 Hz), 2.89 (1H, d, J ) 4.9 Hz), 2.66 (1H, ddd, J ) 7.2,
10.9, 15.7 Hz), 2.49 (1H, ddd, J ) 3.8, 7.1, 15.7 Hz), 2.22 (1H,
ddd, J ) 3.9, 7.1, 13.4 Hz), 1.31, 1.28, 1.13, 1.09, 1.010, 1.005,
0.90 (each 3H, s). 13C NMR (CDCl3): δ 216.1, 200.3, 178.5,
176.8, 124.2, 52.0, 51.1, 49.7, 47.7, 47.5, 45.6, 42.0, 39.6, 37.2,
36.0, 34.7, 34.3, 33.5, 33.0, 32.2, 31.7, 30.8, 28.3, 26.4, 24.0,
23.8, 23.3, 22.9, 21.8, 21.6, 19.3. EIMS (70 eV) m/z: 482 [M]+
(16), 467 (56), 423 (13), 407 (23), 315 (100), 255 (62), 246 (63).
HREIMS Calcd for C31H46O4: 482.3396. Found: 482.3392.
Meth yl 3,11-Dioxou r s-12-en -28-oa te (48). To a solution
of 47 (144 mg, 0.30 mmol) in acetone (14 mL) in an ice bath
was added J ones reagent dropwise until the color of the
solution changed to pale brown from green. The mixture was
stirred at room temperature for 10 min. After removal of
acetone, water was added to the resultant mixture. The
aqueous mixture was extracted with a mixture of CH2Cl2 and
Et2O (1:2) (three times). The extract was worked up according
to the standard method to give 48 as an amorphous solid (128
mg, 89%): UV (EtOH) λmax (log ꢀ): 252 (4.11) nm. IR (KBr):
3â-Hyd r oxyolea n -9(11)-en -28-oic Acid (57).35 A mixture
of 52 (2.27 g, 4.31 mmol), KOH (22 g), and anhydrous
hydrazine (98%) (25 mL) in diethylene glycol (200 mL) was
heated under reflux (inside temperature, 165 °C) for 1.5 h.
Excess hydrazine was distilled off from the mixture until the
inside temperature rose to 215 °C. Then, the mixture was
heated under reflux (inside temperature, 215-220 °C) for 6
h. The mixture was poured into water (500 mL). Aqueous HCl
solution (6 M) was added to give a precipitate. The precipitate
(dry weight, 1.76 g) was filtered and washed with water
(several times). The filtrate was extracted with a mixture of
CH2Cl2 and Et2O (1:2) (three times). The extract was worked
up according to the standard method to give a solid (0.36 g).
The combined solids were crystallized from a mixture of CH2-
Cl2 and MeOH (1:1) to afford 57 as colorless crystals (first crop,
670 mg; second crop, 180 mg). The solid obtained from the
mother liquid was subjected to flash column chromatography
[hexanes-EtOAc (2:1)] to give 57 as crystalline solid (200 mg,
total weight: 1050 mg; 53%): mp >275 °C dec. IR (KBr): 3467,
1
2949, 2869, 1726, 1709, 1654 cm-1. H NMR (CDCl3): δ 5.65
(1H, s), 3.63 (3H, s), 2.96 (1H, ddd, J ) 4.2, 7.1, 13.4 Hz), 2.65
(1H, ddd, J ) 7.1, 11.2, 15.9 Hz), 2.45 (1H, d, J ) 11.5 Hz),
2.40 (1H, s), 2.37 (1H, ddd, J ) 4.2, 6.5, 15.9 Hz), 2.10 (1H,
ddd, J ) 4.6, 14.7, 14.7 Hz), 1.31, 1.26, 1.10, 1.06 (each 3H, s),
0.98 (3H, d, J ) 6.3 Hz), 0.95 (3H, s), 0.88 (3H, d, J ) 6.3 Hz).
13C NMR (CDCl3): δ 217.5, 199.3, 177.4, 163.6, 130.7, 60.9,
55.6, 52.9, 52.1, 47.9, 47.8, 44.7, 44.0, 39.9, 38.8, 36.9, 36.1,
34.4, 32.6, 30.5, 28.6, 26.6, 24.1, 21.6, 21.2, 21.1, 18.9, 17.3,
15.7. EIMS (70 eV) m/z: 482 [M]+ (25), 467 (20), 423 (10), 317
(100), 276 (47), 257 (74). HREIMS Calcd for C31H46O4: 482.3396.
Found: 482.3400. This material was used for the next reaction
without further purification.
Meth yl 3â-Hyd r oxy-12-oxoolea n a n -28-oa te (50). 50 was
prepared from methyl 3â-acetoxy-12-oxooleanan-28-oate (49)12
according to the same method as for 47 to give a crystalline
solid (quantitative): mp 133-135 °C. IR (KBr): 3540, 2945,
3305, 2947, 2875, 1692 cm-1 1H NMR [acetone-d6, internal
.
standard: δ 2.05 (CD2HCOCD3)]: δ 5.35 (1H, t, J ) 3.7 Hz),
3.11 (1H, dd, J ) 6.8, 9.0 Hz), 1.14, 1.11, 0.98, 0.94, 0.93, 0.89,
0.78 (each 3H, s). EIMS (70 eV) m/z: 456 [M]+ (32), 446 (26),
441 (15), 302 (16), 248 (100). HREIMS Calcd for C30H48O3:
456.3603. Found: 456.3603.
1
2866, 1725, 1698 cm-1. H NMR (CDCl3): δ 3.67 (3H, s), 3.18
(1H, dd, J ) 5.0, 10.9 Hz), 2.77 (1H, ddd, J ) 3.4, 4.2, 13.4
Hz), 2.60 (1H, d, J ) 4.2 Hz), 2.14 (2H, m), 1.84 (2H, m), 0.98,
0.96, 0.95, 0.93, 0.89, 0.84, 0.77 (each 3H, s). 13C NMR
(CDCl3): δ 212.0, 178.6, 78.8, 55.3, 52.0, 49.9, 47.5, 42.1, 41.4,
39.0, 38.7, 38.1, 37.1, 36.4, 34.6, 33.6, 33.1, 32.1, 32.0, 30.8,
28.1, 27.7, 27.2, 23.3, 22.9, 20.7, 18.5, 16.3, 15.5, 15.4. EIMS
(70 eV) m/z: 486 [M]+ (37), 471 (100), 411 (65), 278 (68), 218
(65). HREIMS Calcd for C31H50O4: 486.3709. Found: 486.3701.
3-Oxoolea n -9(11)-en -28-oic Acid (58). 58 was prepared
from 57 according to the same method as for 48 to give an
amorphous solid (95%): IR (KBr): 2947, 2870, 1708, 1694
1
cm-1. H NMR (CDCl3): δ 5.38 (1H, t, J ) 3.4 Hz), 2.63 (1H,
ddd, J ) 7.1, 11.5, 15.9 Hz), 2.42 (1H, ddd, J ) 3.7, 6.8, 15.9
Hz), 1.25, 1.13, 1.09, 0.97, 0.94 (each 3H, s), 0.90 (6H, s). 13C
NMR (CDCl3): δ 217.9, 185.2, 152.5, 118.7, 52.8, 48.1, 47.7,
43.8, 38.7, 38.6, 38.4, 36.2, 35.7, 34.9, 34.4, 33.7, 33.6, 33.2,
31.8, 30.8, 28.6, 27.3, 26.3, 25.5, 24.9, 23.6, 23.5, 21.5, 19.6,
18.7. EIMS (70 eV) m/z: 454 [M]+ (32), 439 (13), 408 (26), 248
(65), 235 (100). HREIMS Calcd for C30H46O3: 454.3447.
Found: 454.3439.
Meth yl 3,12-Dioxoolea n a n -28-oa te (51). 51 was prepared
from 50 according to the same method as for 48 to give an
amorphous solid (98%): IR (KBr): 2948, 2866, 1723, 1702
cm-1. 1H NMR (CDCl3): δ 3.69 (3H, s), 2.80 (1H, ddd, J ) 3.7,
4.4, 13.7 Hz), 2.64 (1H, d, J ) 4.4 Hz), 2.53 (1H, ddd, J ) 7.2,
10.9, 15.9 Hz), 2.40 (1H, ddd, J ) 3.8, 7.0, 15.9 Hz), 2.23 (2H,
m), 1.09, 1.05, 1.01, 0.983, 0.976, 0.95, 0.90 (each 3H, s). 13C
NMR (CDCl3): δ 217.1, 211.4, 178.6, 55.1, 52.0, 49.4, 47.6, 47.5,
42.2, 41.4, 38.8, 36.8, 36.4, 34.6, 34.1, 33.6, 33.1, 32.2, 31.3,
30.8, 27.8, 26.4, 23.3, 22.9, 21.4, 20.7, 19.7, 16.1, 15.0. EIMS
(70 eV) m/z: 484 [M]+ (4.2), 469 (39), 409 (100), 357 (6.7), 278
Meth yl 3-Oxoolea n a -1,11,13(18)-tr ien -28-oa te (60). 60
was prepared from methyl 3-oxooleana-11,13(18)-dien-28-oate
(59)17 according to the same method as for 9. The crude solid
was subjected to flash column chromatography [hexanes-
EtOAc (6:1)] to give 60 as a crystalline solid (66%): mp 131-
133 °C. UV (EtOH) λmax (log ꢀ): 246 (4.54), 252 (4.54) nm. IR
(25), 218 (72). HREIMS Calcd for
Found: 484.3544.
C31H48O4: 484.3553.
1
Meth yl 3â-Hyd r oxy-12-oxoolea n -9(11)-en -28-oa te (53).
53 was prepared from methyl 3â-acetoxy-12-oxoolean-9(11)-
en-28-oate (52)14 according to the same method as for 47 to
give an amorphous solid (97%): UV (EtOH) λmax (log ꢀ): 250
(KBr): 3029, 2944, 2859, 1726, 1674 cm-1. H NMR (CDCl3):
δ 7.27 (1H, d, J ) 10.3 Hz), 6.57 (1H, dd, J ) 2.9, 10.5 Hz),
5.89 (1H, d, J ) 10.3 Hz), 5.79 (1H, dd, J ) 1.7, 10.5 Hz), 3.68
(3H, s), 2.54 (1H, d, J ) 14.4 Hz), 2.28 (2H, m), 1.91 (1H, m),

4244 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
1.18, 1.17, 1.10, 0.98, 0.95, 0.86, 0.81 (each 3H, s). 13C NMR
(CDCl3): δ 205.5, 177.1, 159.1, 136.2, 133.2, 126.7, 125.7, 125.0,
53.4, 52.0, 48.6, 48.4, 45.0, 42.4, 41.7, 40.8, 39.3, 37.0, 35.6,
32.8, 32.4, 32.0, 27.7, 25.2, 24.3, 21.32, 21.27, 20.0, 19.2, 16.7.
EIMS (70 eV) m/z: 464 [M]+ (84), 449 (13), 405 (100), 327 (14),
267 (19), 239 (29). HREIMS Calcd for C31H44O3: 464.3290.
Found: 464.3293.
method as for 62 to give a crystalline solid (98%): mp 232-
234 °C. UV (EtOH) λmax (log ꢀ): 254 (4.15), 296 (3.91) nm. IR
(KBr): 3456, 2944, 2867, 1728, 1656, 1589 cm-1 1H NMR
.
(CDCl3): δ 14.87 (1H, d, J ) 2.7 Hz), 8.62 (1H, d, J ) 2.7 Hz),
5.69 (1H, s), 3.64 (3H, s), 3.49 (1H, d, J ) 14.8 Hz), 3.03 (1H,
dd, J ) 3.6, 13.9 Hz), 2.40 (1H, s), 2.05 (1H, ddd, J ) 4.1, 13.7,
13.7 Hz), 1.93 (1H, d, J ) 14.8 Hz), 1.36, 1.18, 1.12, 1.08, 0.95,
0.94, 0.93 (each 3H, s). 13C NMR (CDCl3): δ 199.9, 189.6, 189.2,
177.6, 169.6, 128.0, 106.0, 59.8, 52.4, 52.1, 46.4, 44.8, 44.5, 43.8,
41.8, 40.2, 39.9, 36.5, 33.8, 33.0, 32.0, 31.7, 30.9, 28.6, 28.0,
23.64, 23.59, 23.1, 21.1, 18.8, 18.7, 14.8. EIMS (70 eV) m/z:
510 [M]+ (14), 495 (21), 451 (22), 446 (42), 435 (22), 317 (31),
257 (100). HREIMS Calcd for C32H46O5: 510.3345. Found:
510.3348.
Meth yl 2-Hyd r oxym eth ylen e-3,12-d ioxoolea n -9(11)-en -
28-oa te (62). To a solution of 54 (4.00 g, 8.29 mmol) in dry
benzene (90 mL) was added ethyl formate (97%) (3.0 mL) and
NaOMe (2.68 g, 50 mmol). The mixture was stirred at room
temperature for 2 h. Then the mixture was diluted with a
mixture of CH2Cl2 and Et2O (1:2) and washed with 5% aqueous
HCl solution (three times). The washings were reextracted
with a mixture of CH2Cl2 and Et2O (1:2) and the combined
organic layers were worked up according to the standard
method to give 62 as an amorphous solid (4.19 g, 99%): UV
(EtOH) λmax (log ꢀ): 252 (3.66), 294 (3.53) nm. IR (KBr): 3461,
2950, 2867, 1724, 1661, 1596 cm-1. 1H NMR (CDCl3): δ 14.86
(1H, d, J ) 2.8 Hz), 8.77 (1H, d, J ) 2.8 Hz), 5.90 (1H, s), 3.70
(3H, s), 3.05 (1H, ddd, J ) 3.1, 4.5, 13.6 Hz), 2.92 (1H, d, J )
4.5 Hz), 2.62 (1H, d, J ) 14.4 Hz), 2.30 (1H, d, J ) 14.4 Hz),
1.28, 1.24, 1.18, 1.17, 1.02, 1.01, 0.91 (each 3H, s). 13C NMR
(CDCl3): δ 200.3, 190.2, 188.3, 178.5, 175.8, 124.4, 105.1, 52.1,
49.7, 48.4, 47.5, 45.6, 42.0, 40.6, 39.3, 37.2, 36.0, 34.7, 33.5,
33.0, 31.7, 31.5, 30.8, 28.5, 28.4, 23.6, 23.3, 23.2, 22.9, 21.8,
21.0, 19.1. EIMS (70 eV) m/z: 510 [M]+ (11), 495 (39), 435 (38),
315 (100), 255 (55). HREIMS Calcd for C32H46O5: 510.3345.
Found: 510.3351. This material was used for the next reaction
without further purification.
Meth yl 11-Oxoisoxa zolo[4,5-b]olea n -12-en -28-oa te (66).
66 was prepared from 65 according to the same method as for
63 to give an amorphous solid (74%): UV (EtOH) λmax (log ꢀ):
250 (4.10) nm. IR (KBr): 2944, 2867, 1728, 1657, 1624 cm-1
.
1H NMR (CDCl3): δ 7.99 (1H, s), 5.71 (1H, s), 3.67 (1H, d, J )
15.5 Hz), 3.64 (3H, s), 3.04 (1H, dd, J ) 3.8, 13.6 Hz), 2.51
(1H, s), 2.06 (1H, ddd, J ) 4.2, 13.9, 13.9 Hz), 2.03 (1H, d, J
) 15.5 Hz), 1.37, 1.31, 1.22, 1.06, 0.96, 0.94, 0.93 (each 3H, s).
13C NMR (CDCl3): δ 199.8, 177.6, 172.4, 169.6, 150.5, 128.1,
109.2, 60.3, 53.5, 52.1, 46.4, 45.1, 44.5, 43.8, 41.8, 38.7, 36.2,
34.9, 33.9, 33.1, 32.1, 31.7, 30.9, 29.1, 28.1, 23.7, 23.6, 23.1,
21.7, 18.7, 18.2, 15.8. EIMS (70 eV) m/z: 507 [M]+ (31), 492
(30), 448 (20), 432 (28), 257 (72), 217 (100). HREIMS Calcd
for C32H45O4N: 507.3349. Found: 507.3345.
Meth yl 2-Cya n o-3,11-d ioxoolea n -12-en -28-oa te (67). 67
was prepared from 66 by the similar method as for 64. The
crude solid was subjected to flash column chromatography
[hexanes-EtOAc (2:1)] to give 67 as an amorphous solid
(92%): UV (EtOH) λmax (log ꢀ): 246 (4.18) nm. IR (KBr): 3411,
2944, 2867, 2200, 1725, 1656 cm-1. 1H NMR of major tautomer
67a (CDCl3): δ 6.40 (1H, brs), 5.67 (1H, s), 3.62 (3H, s), 3.33
(1H, d, J ) 15.9 Hz), 3.02 (1H, dd, J ) 3.7, 13.7 Hz), 2.53 (1H,
s), 2.36 (1H, d, J ) 15.9 Hz), 1.33, 1.15, 1.11, 1.08 (each 3H,
s), 0.92 (6H, s), 0.87 (3H, s). EIMS (70 eV) m/z: 507 [M]+ (3.7),
492 (5.2), 447 (5.8), 432 (8.4), 276 (7.0), 257 (21), 217 (31), 84
Met h yl 12-Oxoisoxa zolo[4,5-b]olea n -9(11)-en -28-oa t e
(63). To a solution of 62 (4.00 g, 7.83 mmol) in EtOH (110 mL)
and water (11 mL) was added hydroxylamine hydrochloride
(5.44 g, 78 mmol). The mixture was heated under reflux for 1
h. The mixture was concentrated in vacuo and water (50 mL)
was added. The mixture was extracted with EtOAc (three
times). The combined organic layers were washed with water
(three times) and saturated aqueous NaCl solution (three
times), dried over MgSO4, and filtered. The filtrate was
evaporated in vacuo to give a solid. The solid was subjected to
flash column chromatography [hexanes-EtOAc (3:1)] to give
63 as an amorphous solid (2.63 g, 66%): UV (EtOH) λmax (log
ꢀ): 238 (3.63) nm. IR (KBr): 2944, 2867, 1724, 1660, 1596
(100). HREIMS Calcd for
507.3349.
C32H45O4N: 507.3349. Found:
Met h yl 2-Hyd r oxym et h ylen e-3,11-d ioxou r s-12-en -28-
oa te (68). 68 was prepared from 48 according to the same
method as for 62 to give an amorphous solid (89%): UV (EtOH)
λmax (log ꢀ): 254 (4.06), 298 (3.84) nm. IR (KBr): 3454, 2978,
1
cm-1. H NMR (CDCl3): δ 8.07 (1H, s), 5.89 (1H, s), 3.70 (3H,
s), 3.05 (1H, ddd, J ) 3.7, 4.6, 13.4 Hz), 2.93 (1H, d, J ) 4.6
Hz), 2.79 (1H, d, J ) 15.1 Hz), 2.40 (1H, d, J ) 15.1 Hz), 1.35,
1.29, 1.27, 1.16, 1.03, 1.01, 0.90 (each 3H, s). 13C NMR
(CDCl3): δ 200.2, 178.5, 176.3, 172.3, 150.4, 124.7, 108.7, 52.1,
49.9, 49.7, 47.5, 45.8, 42.0, 41.5, 36.1, 35.4, 34.7, 33.8, 33.5,
33.0, 31.7, 31.5, 30.9, 29.0, 28.4, 24.8, 23.29, 23.25, 22.9, 21.8,
21.6, 18.5. EIMS (70 eV) m/z: 507 [M]+ (14), 492 (51), 446 (25),
432 (49), 315 (100). HREIMS Calcd for C32H45O4N: 507.3349.
Found: 507.3354.
1
2931, 2866, 1728, 1659, 1619, 1590 cm-1. H NMR (500 MHz,
by a Varian Unityplus, CDCl3): δ 14.87 (1H, d, J ) 3.2 Hz),
8.63 (1H, d, J ) 3.2 Hz), 5.67 (1H, s), 3.63 (3H, s), 3.46 (1H, d,
J ) 14.9 Hz), 2.46 (1H, d, J ) 11.2 Hz), 2.40 (1H, s), 2.10 (1H,
m), 1.98 (1H, d, J ) 14.9 Hz), 1.31, 1.20, 1.13, 1.12 (each 3H,
s), 0.98 (1H, d, J ) 6.3 Hz), 0.96 (3H, s), 0.88 (3H, d, J ) 6.6
Hz). 13C NMR (125.705 MHz, by a Varian Unityplus, CDCl3):
δ 199.4, 189.7, 189.2, 177.4, 163.7, 130.9, 106.0, 59.5, 53.0, 52.4,
52.1, 47.9, 44.4, 44.0, 40.2, 40.0, 38.9, 38.8, 36.5, 36.1, 32.2,
30.5, 28.7, 28.6, 24.1, 21.2, 21.1, 18.9, 18.7, 17.3, 14.9. EIMS
(70 eV) m/z: 510 [M]+ (15), 495 (48), 435 (42), 315 (100), 274
Meth yl 2-Cya n o-3,12-d ioxoolea n -9(11)-en -28-oa te (64).
To a solution of 63 (2.00 g, 3.94 mmol) in MeOH (60 mL) and
Et2O (125 mL) in an ice bath was added NaOMe (7.25 g, 134
mmol). The mixture was stirred at room temperature for 45
min and then diluted with a mixture of CH2Cl2 and Et2O (1:
2). It was washed with 5% aqueous HCl solution (three times)
and the acidic washings were reextracted with a mixture of
CH2Cl2 and Et2O (1:2). The combined organic layers were
worked up according to the standard method to give 64 as an
amorphous solid (2.00 g, quantitative): UV (EtOH) λmax (log
ꢀ): 242 (4.16) nm. IR (KBr): 3411, 2944, 2867, 2206, 1722,
(22), 255 (57). HREIMS Calcd for
Found: 510.3347.
C32H46O5: 510.3345.
Met h yl 11-Oxoisoxa zolo[4,5-b]u r s-12-en -28-oa t e (69).
69 was prepared from 68 according to the same method as for
63 to give an amorphous solid (81%): UV (EtOH) λmax (log ꢀ):
248 (4.09) nm. IR (KBr): 2973, 2937, 2866, 1727, 1658, 1619
1
cm-1. H NMR (500 MHz, by a Varian Unityplus, CDCl3): δ
7.99 (1H, s), 5.68 (1H, s), 3.64 (1H, d, J ) 15.6 Hz), 3.63 (3H,
s), 2.50 (1H, s), 2.46 (1H, d, J ) 11.5 Hz), 2.11 (1H, m), 2.07
(1H, d, J ) 15.6 Hz), 1.33, 1.31, 1.23, 1.09 (each 3H, s), 0.98
(3H, d, J ) 6.6 Hz), 0.97 (3H, s), 0.89 (3H, d, J ) 6.6 Hz). 13C
NMR (125.705 MHz, by a Varian Unityplus, CDCl3): δ 199.2,
177.3, 172.4, 163.7, 150.5, 130.8, 109.2, 60.0, 53.5, 52.9, 52.1,
47.8, 44.7, 44.0, 38.9, 38.8, 38.6, 36.2, 36.1, 34.9, 32.3, 30.5,
29.1, 28.7, 24.1, 21.7, 21.2, 21.1, 18.7, 18.2, 17.3, 15.8. EIMS
(70 eV) m/z: 507 [M]+ (9.3), 492 (13), 317 (13), 257 (24), 217
(12), 84 (100). HREIMS Calcd for C32H45O4N: 507.3349.
Found: 507.3351.
1661, 1636, 1597 cm-1 1H NMR of major tautomer 64a
.
(CDCl3): δ 7.08 (1H, brs), 5.75 (1H, s), 3.67 (3H, s), 3.01 (1H,
ddd, J ) 3.7, 4.6, 13.7 Hz), 2.89 (1H, d, J ) 4.6 Hz), 2.40 (1H,
d, J ) 15.3 Hz), 2.23 (1H, d, J ) 15.3 Hz), 1.24, 1.21, 1.19,
1.11 (each 3H, s), 0.98 (6H, s), 0.88 (3H, s). EIMS (70 eV) m/z:
507 [M]+ (84), 492 (99), 432 (58), 315 (100). HREIMS Calcd
for C32H45O4N: 507.3349. Found: 507.3340. This material was
used for the next reaction without further purification.
Met h yl 2-H yd r oxym et h ylen e-3,11-d ioxoolea n -12-en -
28-oa te (65). 65 was prepared from 45 according to the same

Synthetic Oleanane and Ursane Triterpenoids
J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22 4245
Meth yl 2-Cya n o-3,11-d ioxou r s-12-en -28-oa te (70). 70
was prepared from 69 by the similar method as for 64. The
crude solid was subjected to flash column chromatography
[hexanes-EtOAc (2:1)] to give 70 as a crystalline solid (94%):
mp 169-171 °C. UV (EtOH) λmax (log ꢀ): 246 (4.17) nm. IR
(KBr): 3401, 2978, 2937, 2866, 2202, 1725, 1668 cm-1. 1H NMR
of major tautomer 70a (500 MHz, by a Varian Unityplus,
CDCl3): δ 5.86 (1H, brs), 5.66 (1H, s), 3.62 (3H, s), 3.33 (1H,
d, J ) 15.7 Hz), 2.45 (1H, d, J ) 10.3 Hz), 2.33 (1H, s), 2.10
(1H, m), 1.92 (1H, d, J ) 15.7 Hz), 1.29, 1.17, 1.15, 1.09 (each
3H, s), 0.97 (3H, d, J ) 6.4 Hz), 0.93 (3H, s), 0.87 (3H, d, J )
6.6 Hz). EIMS (70 eV) m/z: 507 [M]+ (25), 492 (31), 467 (45),
446 (54), 317 (34), 276 (26), 257 (85), 217 (100). HREIMS Calcd
for C32H45O4N: 507.3349. Found: 507.3351.
Meth yl 3-Hyd r oxy-2-m eth oxyca r bon yl-12-oxoolea n a -
2,9(11)-d ien -28-oa te (71). A mixture of 54 (258 mg, 0.53
mmol) and 1.8 M DMF solution of methoxymagnesium methyl
carbonate (Stiles’ reagent) (2.5 mL, 4.5 mmol) was heated at
110 °C for 1 h while a slow stream of N2 was bubbled through
the mixture with a pipet. To the mixture were added 5%
aqueous HCl solution and EtOAc. The aqueous layer was
extracted with EtOAc (three times). The combined organic
layers were washed with water (three times) and saturated
aqueous NaCl solution (three times), dried over MgSO4, and
filtered. The filtrate was evaporated in vacuo to give a solid
(305 mg). To a solution of the solid in THF (6 mL) was added
excessive amount of ethereal diazomethane. The mixture was
kept at room temperature for 10 min. The mixture was
evaporated in vacuo to give a solid (310 mg). The solid was
subjected to flash column chromatography [hexanes-EtOAc
(4:1)] to give 71 as crystals (225 mg, 78%): mp 210-211 °C.
UV (EtOH) λmax (log ꢀ): 252 (4.20) nm. IR (KBr): 2944, 2867,
1725, 1661, 1618 cm-1. 1H NMR (CDCl3): δ 12.49 (1H, s), 5.94
(1H, s), 3.76, 3.69 (each 3H, s), 3.04 (1H, ddd, J ) 3.1, 4.9,
13.2 Hz), 2.90 (1H, d, J ) 4.9 Hz), 2.70 (1H, d, J ) 15.3 Hz),
2.06 (1H, d, J ) 15.3 Hz), 1.26, 1.20, 1.17, 1.14 (each 3H, s),
1.00 (6H, s), 0.89 (3H, s). 13C NMR (CDCl3): δ 200.5, 178.5,
176.9, 176.7, 173.9, 124.5, 94.1, 52.0, 51.8, 49.7, 48.6, 47.5, 45.6,
42.0, 39.3, 38.6, 36.3, 36.1, 34.7, 33.5, 33.1, 31.7, 31.5, 30.8,
28.6, 28.4, 24.3, 23.3, 23.2, 22.9, 21.8, 20.4, 19.1. EIMS (70
eV) m/z: 540 [M]+ (3.9), 525 (5.7), 508 (23), 493 (54), 433 (35),
315 (100). HREIMS Calcd for C33H48O6: 540.3451. Found:
540.3454.
Cyanamid), and Dr. Mark G. Saulnier (Bristol-Myers
Squibb) for the mass spectra and also Prof. David A.
Evans and Mr. Brett D. Allison (Harvard University)
for the optical rotation measurements. This investiga-
tion was supported by funds from NIH Grant 1 R01-
CA78814, the Norris Cotton Cancer Center, U.S.
Department of Defense Grants DAMD17-96-1-6163,
DAMD17-98-1-8604, and DAMD17-99-1-9168, the
Oliver and J ennie Donaldson Charitable Trust, the
National Foundation for Cancer Research, and a Zenith
Award from the Alzheimer’s Association. M.B.S. is
Oscar M. Cohn Professor, F.G.F., J r. is an Oscar M.
Cohn Scholar, and Y.W. is a Howard Hughes Medical
Institute Predoctoral Fellow.
Refer en ces
(1) (a) Connolly, J . D.; Overton, K. H. The Triterpenoids. In
Chemistry of Terpenes and Terpenoids; Newman, A. A., Ed.;
Academic Press: New York, 1972; pp 207-287. (b) Nakanishi,
K.; Ito, S. Biosynthesis of oleanene and ursene triterpenes in
tissue culture of Isodon japonicus. In Natural Products Chem-
istry; Nakanishi, K., Goto, T., Ito, S., Natori, S., Nozoe, S., Eds.;
Kodansha: Tokyo, 1983; Vol. 3, pp 185-187.
(2) Devon, T. K.; Scott, A. I. The Terpenes. Handbook of Naturally
Occurring Compounds; Academic Press: New York, 1972; Vol.
2, pp 281-384.
(3) (a) Yu, L.; Ma, R.; Wang, Y.; Nishino, H.; Takayasu, J .; He, W.;
Chang, M.; Zhen, J .; Liu, W.; Fan, S. Potent anti-tumorigenic
effect of tubeimoside 1 isolated from the bulb of Bolbostemma
paniculatum (Maxim) Franquet. Int. J . Cancer 1992, 50, 635-
638. (b) Liu, J . Pharmacology of oleanolic acid and ursolic acid.
J . Ethnopharmacol. 1995, 49, 57-68 and references therein. (c)
Sakurawi, K.; Yasuda, F.; Tozyo, T.; Nakamura, M.; Sato, T.;
Kikuchi, J .; Terui, Y.; Ikenishi, Y.; Iwata, T.; Takahashi, K.;
Konoike, T.; Mihara, S.; Fujimoto, M. Endothelin receptor
antagonist triterpenoid, myriceric acid A, isolated from Myrica
cerifera, and structure activity relationships of its derivatives.
Chem. Pharm. Bull. 1996, 44, 343-351. (d) Kashiwada, Y.;
Wang, H.-K.; Nagao, T.; Kitanaka, S.; Yasuda, I.; Fujioka, T.;
Yamagishi, T.; Cosentino, L. M.; Kozuka, M.; Okabe, H.;
Ikeshiro, Y.; Hu, C.-Q.; Yeh, E.; Lee, K.-H. Anti-AIDS agents.
30. Anti-HIV activity of oleanolic acid, pomolic acid, and
structurally related triterpenoids. J . Nat. Prod. 1998, 61, 1090-
1095.
Eva lu a tion Meth od s. 1. Rea gen ts. Recombinant mouse
IFN-γ (LPS content, <10 pg/mL) was purchased from Genzyme
(Cambridge, MA). All other chemicals were purchased from
Sigma Chemical Co. (St. Louis, MO). Inhibitory test com-
pounds were dissolved in DMSO before addition to cell
cultures; final concentrations of DMSO were 0.1% or less.
Controls with DMSO alone were run in all cases.
2. Cell Cu ltu r e. To obtain primary macrophages, female
CD-1 mice, 5-10 weeks of age (Charles River Breeding
Laboratories, Wilmington, MA), were injected intraperitoneally
with 2 mL of 4% thioglycollate broth (Difco Laboratories,
Detroit, MI). Four days after injection, peritoneal macrophages
were harvested and processed according to Nathan’s procedure.4b
Cells were seeded in 96-well plates at 2 × 105 cells/well and
incubated for 48 h with 20 ng/mL IFN-γ in the presence or
absence of inhibitory test compounds
3. Mea su r em en t of NO P r od u ction in Mou se Ma cr o-
p h a ges. Nitrite accumulation was used as an indicator of NO
production in the medium and was assayed by the Griess
reaction.4a Griess reagent (100 µL) was added to 100 µL of each
supernatant from IFN-γ or inhibitory test compound-treated
cells in triplicate. The protein determination was performed
by Bradford protein assay. The plates were read at 550 nm
against a standard curve of sodium nitrite.
(4) (a) Ding, A.; Nathan, C. F.; Graycar, J .; Derynck, R.; Stuehr, D.
J .; Srimal, S. Macrophage deactivating factor and transforming
growth factors-â1, -â2, and -â3 inhibit induction of macrophage
nitrogen oxide synthesis by IFN-γ. J . Immunol. 1990, 145, 940-
944. (b) Bogdan, C.; Paik, J .; Vodovotz, Y.; Nathan, C. Contrast-
ing mechanisms for suppression of macrophage cytokine release
by transforming growth factor-â and interleukin-10. J . Biol.
Chem. 1992, 267, 23301-23308.
(5) Honda, T.; Gribble, G. W.; Suh, N.; Finlay, H. J .; Rounds, B. V.;
Bore, L.; Favarolo, F. G., J r.; Wang, Y.; Sporn, M. B. Novel
synthetic oleanane and ursane triterpenoids with various enone
functionalities in ring A as inhibitors of nitric oxide production
in mouse macrophages. J . Med. Chem. 2000, 43, 1866-1877.
(6) Because the following paper reported that H2O2-acetic acid
oxidation of methyl 3â-acetoxyurs-12-en-28-oate did not give
methyl 3â-acetoxy-12-oxoursan-28-oate (cf. 49), we have not
designed and synthesized various ursane triterpenoids with a
carbonyl group at C-12 (cf. for example: 9, 10, 16, 17, 25, and
26): Tkachev, A. V.; Denisov, A. Y.; Gatilov, Y. V.; Bagryan-
skaya, I. Y.; Shevtsov, S. A.; Rybalova, T. V. Stereochemistry of
hydrogen peroxide-acetic acid oxidation of ursolic acid and
related compounds. Tetrahedron 1994, 50, 11459-11488.
(7) Wrzeciono, U.; Zaprutko, L.; Budzianowski, J .; Wojtowicz, H.;
Dubowska, D. Triterpenoids Part II - Carbon-13 NMR spectra
of 18â- and 18R-11-oxooleanolic acid derivatives. Magn. Reson.
Chem. 1987, 25, 223-226.
(8) Sharpless, K. B.; Lauer, R. F.; Teranishi, A. Y. Electrophilic and
nucleophilic organoselenium reagents. New routes to R,â-
unsaturated carbonyl compounds. J . Am. Chem. Soc. 1973, 95,
6137-6139.
(9) Dean, P. D. G. Halogenolysis of methyl glycyrrhetate with
lithium iodide-dimethylformamide. J . Chem. Soc. C 1965, 6655.
(10) Barton, D. H. R.; Holness, N. J . Triterpenoids. Part V. Some
relative configurations in rings C, D, and E of the â-amyrin and
the lupeol group of triterpenoids. J . Chem. Soc. 1952, 78-92.
(11) Halogenolysis of 13 and 33 with LiI in DMF did not give â,γ-
unsaturated ketones which correspond to 15 and 35.
Ack n ow led gm en t. We thank Drs. Carl Nathan and
Qiao-wen Xie for expert advice on the preparation of
macrophages and the nitric oxide assay. We also thank
Dr. Steven Mullen (University of Illinois), Dr. Mary K.
Young and Mr. Ron New (UC Riverside), Dr. Stephen
W. Wright (Pfizer), Dr. Timothy C. Barden (American

4246 J ournal of Medicinal Chemistry, 2000, Vol. 43, No. 22
Honda et al.
(12) Ruzicka, L.; Cohen, S. L. Polyterpene und Polyterpenoide CXIII.
Oxydationen in der Reihe der Oleanolsa¨ure ohne Sprengung des
Ringsystems. U¨ ber die Natur des vierten Sauerstoffatoms der
Glycyrrhetinsa¨ure. Helv. Chim. Acta 1937, 20, 804-808.
(13) It was confirmed by a NOSEY experiment in CDCl3 that the
proton at C-13 of 49 [δ 2.61 ppm (d, J ) 4.4 Hz)] has a cis
relationship to the â-proton at C-18 [δ 2.80 ppm (ddd, J ) 3.3,
4.4, and 13.9 Hz)].
(14) Picard, C. W.; Sharples, K. S.; Spring, F. S. The triterpene
resinols and related acids. Part VI. J . Chem. Soc. 1939, 1045-
1048.
(15) Dietrich, P.; J eger, O. Zur Kenntnis der Triterpene. U¨ berfu¨hrung
von Betulin und Oleanolsa¨ure in isomere ungesa¨ttigte Kohlen-
wasserstoffe C29H48. Hypothese u¨ber die Biosynthese pentacy-
clischer Triterpene. Helv. Chim. Acta 1950, 33, 711-722.
(16) Although 1H and 13C NMR of 21 in CDCl3 showed that it is a
single isomer (see Experimental Section), the configuration of
the 9,11-epoxide has not been elucidated.
(27) This adduct 72 could not be isolated in pure state because it
was readily transformed into 28 under purification conditions.
Although this adduct was shown to be the single tautomer as
depicted in Scheme 6 by 1H NMR, the configuration of methoxy
group at C-1 is unknown. Cf.: When we prepared 2-methoxy-
carbonyl-3-oxooleana-1,12-dien-28-oic acid (40) from 2-carboxy-
3-oxooleana-1,12-dien-28-oic acid (7) under the same acidic
conditions, such a Michael adduct was not obtained at all (see
ref 5).
(28) Gagne, D.; Pons, M.; Philibert, D. RU38486: a potent antiglu-
cocorticoid in vitro and in vivo. J . Steroid Biochem. 1985, 23,
247-251.
(29) Suh, N.; Wang, Y.; Honda, T.; Gribble, G. W.; Dmitrovsky, E.;
Hickey, W. F.; Maue, R. A.; Place, A. E.; Porter D. M.; Spinella,
M. J .; Williams, C. R.; Wu, G.; Dannenberg, A. J .; Flanders, K.
C.; Letterio, J . J .; Mangelsdorf, D. J .; Nathan, C. F.; Nguyen,
L.; Porter, W. W.; Ren, R. F.; Roberts, A. B.; Roche, N. S.,
Subbaramaiah, K.; Sporn, M. B. A novel synthetic oleanane
triterpenoid, 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid, with
potent differentiating, antiproliferative, and anti-inflammatory
activity. Cancer Res. 1999, 59, 336-341.
(30) Adipogenic differentiation of mouse 3T3-L1 fibroblasts is due
to CDDO being a ligand for the peroxisome proliferator-activated
receptor γ: Wang, Y.; Porter, W. W.; Suh, N.; Honda, T.; Gribble,
G. W.; Mangelsdorf, D. J .; Blanchard, S. G.; Willson, T. M.;
Sporn, M. B. A synthetic triterpenoid, 2-cyano-3,12-dioxooleana-
1,9-dien-28-oic acid (CDDO), is a ligand for the peroxisome
proliferator-activated receptor γ. Presented at the 91st Annual
Meeting of the American Association for Cancer Research, San
Francisco, CA, Apr. 1-5, 2000; Proceedings, p 28.
(17) Asada, M.; Amagaya, S.; Takai, M.; Ogihara, Y. New triterpe-
noids from the leaves of Tetrapanax papyriferum. J . Chem. Soc.,
Perkin Trans. 1 1980, 325-329.
(18) Honda, T.; Finlay, H. J .; Gribble, G. W. Partial synthesis of
krukovines A and B, triterpene ketones isolated from the
Brazilian medicinal plant Maytenus krukovii. J . Nat. Prod. 1997,
60, 1174-1177.
(19) Reflux conditions decreased the yield from 78% to 53%.
(20) Ratcliffe, R.; Rodehorst, R. Improved procedure for oxidations
with the chromium trioxide-pyridine complex. J . Org. Chem.
1970, 35, 4000-4002.
(21) 1H and 13C NMR of 62, 65 and 68 in CDCl3 showed that they
are the single tautomer depicted in Scheme 5 (see Experimental
Section).
(22) Clinton, R. O.; Manson, A. J .; Stonner, F. W.; Neumann, H. C.;
Christiansen, R. G.; Clarke, R. L.; Ackerman, J . H.; Page, D. F.;
Dean, J . W.; Dickinson W. B.; Carabateas, C. Steroidal[3,2-c]-
pyrazoles. II. Androstanes, 19-norandrostanes and their unsat-
urated analogs. J . Am. Chem. Soc. 1961, 83, 1478-1491.
(23) J ohnson, W. S.; Shelberg, W. E. A plan for distinguishing
between some five- and six-membered ring ketones. J . Am.
Chem. Soc. 1945, 67, 1745-1754.
(31) Suh, N.; Wang, Y.; Williams, C.; Risingsong, R.; Honda, T.;
Rounds, B. V.; Bore, L.; Gribble, G. W.; Sporn, M. B. CDDO, a
novel synthetic oleanane triterpenoid, suppresses nitric oxide
production and synthesis of inducible nitric oxide synthase
(iNOS) in female CD-1 mice. Presented at the 91st Annual
Meeting of the American Association for Cancer Research, San
Francisco, CA, Apr. 1-5, 2000; Proceedings, p 663.
(32) Brieskorn, C. H.; Seifert, M. Methylgruppen-Umlagerungen an
Triterpenoiden, 2. Mitt. Aromatisierung des Ringes A. Arch.
Pharm. 1982, 315, 846-851.
(33) Begum, S.; Adil, Q.; Siddiqui, B. S.; Siddiqui, S. Synthesis of
2â-hydroxyursolic acid and other ursane analogues from ursonic
acid. Aust. J . Chem. 1993, 46, 1067-1071.
(34) These spectral data were calculated by subtracting the data of
28 from those obtained from a mixture of 28 and 72.
(35) Because of the low solubility in various solvents, 13C NMR could
not be measured.
(24) 1H NMR in CDCl3 showed that 64, 67, and 70 are each a mixture
of three tautomers [64a , 67a , 70a ; 64b, 67b, 70b (2R-cyano);
and 64c, 67c, 70c (2â-cyano)], and the major ones are 64a , 67a ,
and 70a , respectively.
(25) Finkbeiner, H. L.; Stiles, M. Chelation as a driving force in
organic reactions. IV. synthesis of R-nitro acids by control of the
carboxylation-decarboxylation equilibrium. J . Am. Chem. Soc.
1963, 85, 616-622.
(26) Liotta, D.; Barnum, C.; Puleo, R.; Zima, G.; Bayer, C.; Kezar,
III, H. S.
A simple method for the efficient synthesis of
unsaturated â-dicarbonyl compounds. J . Org. Chem. 1981, 46,
2920-2923.
J M0002230