Synthesis of phosphonodipeptide conjugates of ursolic acid and their homologs

Article abstract of DOI:10.1002/hc.20396

To prepare novel derivatives of naturally bioactive 3β-hydroxy-urs-12- en-28-oic acid (ursolic acid) with unusual properties and broad spectrum of activities, a number of chemical reactions were conducted. First, a variety of a-aminophosphonates were prepared by a series of reactions involving the three-component Mannich type reaction as a key step. Second, an array of phosphonodipeptides and their homologs was synthesized through multistep reactions including condensation of phthalic anhydride with glycine or β-alanine, chlorination of N-blocked amino acids, coupling of acid chloride with α-aminophosphonates and sequential hydrazinolysis. Finally, new classes of phosphonodipeptide conjugates of ursolic acid and their homologs were obtained by condensation of 3β-acetoxy-urs-12-en-28-oyl chloride with phosphonodipeptides and their homologs.

Full text of DOI:10.1002/hc.20396

Heteroatom Chemistry
Volume 19, Number 1, 2008
Synthesis of Phosphonodipeptide Conjugates
of Ursolic Acid and Their Homologs
Sheng-Lou Deng,1 Isabelle Baglin,1 Mohammed Nour,2
and Christian Cave´3
1Unite´ de Mole´cules d’Inte´reˆt Biologique, EA 3660, UFR de Pharmacie, BP 87900,
21079 Dijon Cedex, France
2IRD, Laboratoire de Pharmacochimie des Substances Naturelles, Universite´ de la Nouvelle
Cale´donie, BP 4477, 98847 Noume´a, Nouvelle Cale´donie, France
3UMR CNRS BioCis 8076, Faculte´ de Pharmacie, 5, Rue J.-B. Cle´ment,
92296 Chaˆtenay-Malabry Cedex, France
Received 7 December 2006; revised 25 February 2007
INTRODUCTION
ABSTRACT: To prepare novel derivatives of naturally
bioactive 3β-hydroxy-urs-12-en-28-oic acid (ursolic
acid) with unusual properties and broad spectrum
of activities, a number of chemical reactions were
conducted. First, a variety of α-aminophosphonates
were prepared by a series of reactions involving the
three-component Mannich type reaction as a key
step. Second, an array of phosphonodipeptides and
their homologs was synthesized through multistep
reactions including condensation of phthalic an-
hydride with glycine or β-alanine, chlorination of
N-blocked amino acids, coupling of acid chloride with
α-aminophosphonates and sequential hydrazinolysis.
Finally, new classes of phosphonodipeptide conju-
gates of ursolic acid and their homologs were ob-
tained by condensation of 3β-acetoxy-urs-12-en-28-
oyl chloride with phosphonodipeptides and their ho-
Ursolic acid (UA) 1 (Fig. 1), a pentacyclic triterpene
compound, naturally occurs in a large variety of veg-
etarian foods, medicinal herbs, and plants [1]. This
terpenoid compound has attracted considerable in-
terest owing to its significant biological activities and
promising clinical application as chemotherapeu-
tic and chemopreventive agent (anti-inflammation
[2], antimicrobial activity [3–5], as well as inhibition
of mutagenesis in bacteria [6]). Moreover, ursolic
derivatives, especially dicarboxylic acid hemiesters,
exhibit antihuman immunodeficiency virus type 1
(anti-HIV-1) activity, though slight toxicity is ob-
served [7–9]. These new derivatives are assumed
to be responsible for inhibition of HIV-1 protease
dimerization [10]. Some ursolic derivatives also
demonstrate anticancer activity. Indeed, UA and its
derivatives display cytotoxic dose-dependent activ-
ity by inhibiting the growth of implanted ascetic tu-
mor cells in vivo [11]. The cytotoxic potential of UA
has also been found by inhibition of B16 cell growth
(mouse melanoma cell lines) [12]. It can also be a
potential candidate in treatment or prevention of
skin cancer and a new promising anticancer agent in
treatment of melanoma by apoptosis induction [13].
It is obviously a potent inhibitor of MCF-7 in the
light of both cytostatic and cytotoxic activity [14].
ꢀ
C
mologs. 2008 Wiley Periodicals, Inc. Heteroatom Chem
19:55–65, 2008; Published online in Wiley InterScience
(www.interscience.wiley.com). DOI 10.1002/hc.20396
Correspondence to: Christian Cave´; e-mail: Christian.cave@cep.
u-psud.fr.
Contract grant sponsor: Conseil Re´gional de Bourgogne.
2008 Wiley Periodicals, Inc.
c
ꢀ
55

56 Deng et al.
Some derivatives of pyrimidinyl or purinyl phospho-
nic acid demonstrate antiviral activity with a broad
spectrum of activities against retrovirus and DNA
virus by inhibiting DNA polymerase [26,27]. In the
past decade, numerous studies have been published
regarding the synthesis of phosphonopeptides with
α-aminophosphonic acid in the C-terminal position
for the purpose of evaluation of their properties re-
lated to metabolic process [26–31].
FIGURE 1 Structure of ursolic acid (UA).
On the basis of our previous work, we designed
and synthesized a number of novel phosphonodipep-
tide conjugates of UA and their homologs to examine
their biological activity.
To facilitate synthesis of phosphorus-containing
conjugates of ursolic acid, carboxylic acid moiety
was first converted to acyl chloride. Coupling of
acyl chloride with phosphonodipeptides, which were
obtained by condensation of α-aminophosphonates
with N-protected amino acid chlorides and sequen-
tial hydrazinolysis, provided desired conjugates. The
biological activity evaluation of the synthesized com-
pounds is in progress.
However, the literature review reveals that only
limited synthetic analogues have been reported for
the purpose of bioactivity evaluation. A number of
new derivatives are still needed for extensive inves-
tigation to establish structure-activity correlation.
Our previous work demonstrated that acylation of
ursolic acid at C-3 position and glycosylation at
C-28 position could yield important compounds
with anti-HT29 (human colon cancer cell) and
anti-HIV activities [15]. More recent study revealed
that α-aminophosphonates conjugates of ursolic
acid (Fig. 2) possessed good anti-HIV activity with
20% inhibition at 10−4 M (R = p-MeOPh). These
phosphorus-containing compounds proved to be
good HIV-1 entry inhibitor capable of inhibiting
CD4-gp120 interaction. Moreover, the derivatives of
α-aminophosphonic acid conjugates are expected to
improve the biological activity [16]. These exciting
results prompted us to continue our synthesis of
more derivatives of ursolic acid through the intro-
duction of bioactive subunit-α-aminophosphonic
acid.
It is well known that phosphonopeptides, as
mimetics of naturally occurring peptides, have
emerged as an important aspect in bioorganic and
medicinal chemistry due to their unique biological
activities [17]. Phosphonopeptides have been shown
to be transition state analogs of the scissile amide
bond, so they are of great interest in development of
enzyme inhibitors [18–20] and haptens for the pro-
duction of catalytic antibodies possessing esterase
activities [21,22]. Some amino phosphonodipeptides
and phosphono-oligopeptides have been used as an-
tibacterial, anticancer, and antibiotic agents [23–25].
RESULTS AND DISCUSSION
A variety of N-protected α-aminophosphonates were
prepared in good to excellent yields (70–93%)
through the one-pot three-component reaction ac-
cording to the literature [32]. The three compo-
nents (benzyl carbomate, aldehyde, triphenylphos-
phite) were used in equal molar ratios. It was found
that slight excess of aldehyde (1.1–1.3 equivalent)
would improve the yield of the expected product,
whereas the higher reaction temperature and longer
reaction time would not affect the result of the re-
action. For the aliphatic aldehydes, the yields were
generally lower compared to that of aromatic alde-
hydes. It was noticed that the products derived from
aromatic aldehyde could precipitate immediately at
room temperature after the reaction was complete,
whereas precipitation of the product from aliphatic
aldehyde usually required harsh conditions such as
cooling (–10◦C) and storage in freezer overnight.
The ammonium hydrobromides were sequen-
tially obtained after deprotection with a solution of
hydrobromide in acetic acid at room temperature
in a short time (0.5–2 h) [32]. Use of excessive hy-
drobromide (>2 equiv.) would speed up the reaction
and gave nearly quantitative yield of the products
(95%–98%).
Transformation of ammonium bromides into
free amine was carried out in alternative ways.
Free ammonia and triethylamine were chosen in
this case, respectively. Neutralization by free am-
monia was performed in large-scale preparation.
FIGURE 2 Structures of the reported compounds.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of Phosphonodipeptide Conjugates of Ursolic Acid and Their Homologs 57
SCHEME 1 Reagents and conditions: (a) AcOH, 80◦C–85◦C, 2 h; (b) HBr/AcOH, rt, 2 h; (c) NEt3/THF.
To facilitate the small-scale reaction, triethylamine
was preferentially used to saponify the correspond-
ing salt even though completion of the reaction
required a little longer time. Thus, the desired
α-aminophosphonates were obtained by treating
hydrobromide derivatives with triethylamine (>3
equiv.) in anhydrous THF. Filtration of salt and
following evaporation of low-boiling point sub-
stances under reduced pressure resulted in free
amines (2) as sticky oils in 50%–75% yields
(Scheme 1). Without further purification, the ob-
tained α-aminophosphonates 2 were then dissolved
in anhydrous THF and used as such in the next
step.
Synthesis of phosphonodipeptides began with
condensation of phthalic anhydride with amino
acids at high temperature (≥180◦C) under solvent-
free condition. It should be noted that both of the
reactants should be well ground and mixed evenly
to ensure entire transformation of starting materials
into the product 3 [33,34]. To complete the reaction,
vigorous stirring was necessary after the solid mix-
ture melted into dark brown liquid. The pure white
crystal was obtained in nearly quantitative yield by
recrystallization from water.
Chlorination of N-protected amino acids by
thionyl chloride was achieved under solvent-free
condition at 60◦C. The excess of thionyl chloride was
removed at 55◦C. It was found that higher tempera-
ture would cause partial decomposition of the prod-
uct. The crude acid chloride generated was used im-
mediately after dissolution in anhydrous THF.
The coupling of acid chloride 4 [35] with
α-aminophosphonates 2 proceeded smoothly on
ice-bath in the presence of triethylamine. The pure
products 5a–f and 6a–d were obtained in 36%–68%
yields after recrystallization from a mixture of
dichloromethane/diethyl ether. The structures of
5a–f and 6a–d were elucidated by spectroscopic
methods.
Phosphonodipeptides 7a–f and homologs 8a–d
were obtained after deprotection of 5a–f and 6a–d by
hydrazinolysis in absolute ethanol overnight at room
temperature (Scheme 2). The reaction usually ended
up with some white precipitate. It should be noted
that the complete removal of precipitate required
repetitive filtration of the reaction mixture (four
times). The filtrate was subject to concentration un-
der reduced pressure at low temperature (≤55◦C).
Interestingly, it was found that in all cases one of
the phosphonate phenyl groups was lost. It just met
our requirement, and consequently, it facilitated our
synthesis of target molecules bearing terminal phos-
phonic acid. Thus, all of compounds 7a–f and 8a–d
obtained from hydrazinolysis were directly used in
the next step without further purification.
The starting material 9 (3β-acetoxy-urs-12-en-
28-oic acid) was quantitatively obtained by treat-
ment of ursolic acid with an excess of acetic anhy-
dride in pyridine in the presence of DMAP as catalyst
[36,37]. Further reaction of compound 9 with exces-
sive thionyl chloride under free-solvent condition at
65◦C afforded acid chloride 10, which was slightly
different from the method reported in the literature
[38]. The excess thionyl chloride was removed under
reduced pressure and inert atmosphere. It was note-
worthy that removal of thionyl chloride should be
performed at 50◦C–60◦C; higher temperature would
lead to decomposition. The crude sticky product was
thus obtained and subject to evaporation on high
vacuum (oil pump). The brown solid furnished was
used without further purification.
Condensation of phosphonodipeptides 7a–f and
their homologs 8a–d with acid chloride 10 was
carried out in anhydrous THF in the presence of
triethylamine under nitrogen atmosphere. Upon
completion of the reaction, the crude mixture was
subject to preparative thin layer chromatography af-
ter routine work-up. The pure products 11a–f and
12a–d were obtained as sticky oil with 8%–24%
Heteroatom Chemistry DOI 10.1002/hc

58 Deng et al.
SCHEME 2 Reagents and conditions: (a) 185◦C–200◦C, 15 min; (b) SOCl2, 60◦C, 3 h; (c) 2, NEt3/THF, 0◦C, 15 min; rt,
overnight; (d) NH2–NH2·H2O, EtOH, rt, 16 h.
yields. Some more polar byproducts were observed
and the structures were unidentified (Scheme 3). The
low yield of desired products and the complication
of the reaction were presumably attributed to inter-
ference of the phosphonic acid.
Compounds 11a–f and 12a–d were characterized
1
by H NMR, 13C NMR, 31P NMR, FT-IR, and mi-
croanalysis. The 1H and 31P NMR spectral data sug-
gested that all of 11a–f and 12a–d consisted of di-
astereoisomers. For example, the 31P NMR spectrum
SCHEME 3 Reagents and conditions: (a) Ac2O, DMAP, pyridine, rt, 2.5 h; (b) SOCl2, 65◦C, 5 h; (c) 7a–f and 8a–d, NEt3/THF,
0◦C, 0.5 h; rt, overnight.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of Phosphonodipeptide Conjugates of Ursolic Acid and Their Homologs 59
of 11c showed two overlapped peaks (18.18 and
continued for another 2 h. The reaction solution
was subjected to evaporation under reduced pres-
sure to remove low-boiling point substances. The
anhydrous methanol (50 mL) was added. The result-
ing mixture was cooled to –10◦C for 3 h, affording a
large amount of white precipitate. The following fil-
tration and washing with anhydrous methanol (2 ×
50 mL) and subsequent drying on vacuum gave de-
sired white powder in 70%–93% yields.
18.04), suggesting the existence of an equimolar mix-
ture of diastereoisomers. In corresponding 1H NMR
spectrum, the signals at 5.23 and 5.24 ppm repre-
senting H-12 moiety appeared as two broad single
peaks, confirming the presence of diastereoisomers.
In summary, a series of α-aminophosphonates
were prepared in a convenient method in good
yields; a variety of phosphonodipeptides and ho-
mologs were also obtained in moderate to good
yields through multistep reactions; the introduction
of phosphonodipeptides and their homologs to urso-
lic acid at C-28 was achieved, affording new classes
of phosphonodipeptide conjugates of ursolic acid
and their homologs. The bioassays such as anti-
HT29 (human colon cancer cell line) and anti-HIV
are in progress.
General Procedure for the Preparation of
Diphenyl-α-aminophosphonates Hydrobromides
To
a
flask containing N-benzyloxycarbonyl-
diphenyl-α-aminophosphonates (0.01 mol),
a
solution of HBr in AcOH (25 mL, 30%) was added.
The mixture was stirred at room temperature for
2 h. When evolution of bubbles stopped, excess
HBr and solvent were subsequently removed by
distillation under reduced pressure. The residue
was washed with diethyl ether (30 mL), producing
white solid. Further filtration and washing with
diethyl ether yielded white powder. The spectral
data of all known products are in accordance with
that reported in the literature.
EXPERIMENTAL
Reagents and solvents were purchased from com-
mercial sources and used without further purifi-
cation unless stated otherwise. Ursolic acid was
purchased from Aldrich-Sigma Co. (L’isle d’Abeau,
38297 Saint Quentin Fallavier, France) Tetrahydro-
furan was dried over sodium before use. Thionyl
chloride and triethylamine were freshly distilled be-
fore use. Ethanol was dried by refluxing with mag-
nesium and iodine. Melting points (mp) were deter-
mined with a Kofler bench and were uncorrected.
General Procedure for the Preparation of
Diphenyl-α-aminophosphonates (2)
To a suspension of diphenyl-α-aminophosphonates
hydrobromide (0.25 mmol) in 20 mL, anhydrous
THF was added dropwise 0.3 mL of triethylamine.
The mixture was kept stirring for about 3 h at room
temperature. The precipitate was then filtered off,
and the solvent was evaporated under reduced pres-
sure. The resulting sticky product was used as such
without further purification.
1
The H, 13C, and 31P NMR spectra were recorded
on a Bruker AC-P300 instrument. All spectra were
recorded in CDCl3; tetramethylsilane (TMS) was
1
used as an internal standard for H NMR, and 85%
phosphoric acid (H3PO4) was used as an external
standard for 31P NMR spectroscopy. IR (KBr) was
preformed on Avatar 360 FT-IR instrument. Ele-
mental analyses were carried out on a Yanaco MT-
3 instrument. Analytical thin layer chromatography
(TLC) was performed on Merck silica gel 60F254 pre-
coated plates. The preparative thin layer chromatog-
raphy was made using silica gel H (10–40 µm) con-
taining F254 as coating. All reactions involving air-
or water-sensitive compounds were routinely con-
ducted under nitrogen atmosphere.
Synthesis of 1,3-Dihydro-1,3-dioxo-2H-
isoindole-2-acetic Acid (3)
To a 100-mL flask, phthalic anhydride (7.5 g, 0.051
mol) and well-ground glycine (3.75 g, 0.050 mol)
were sequentially added. The mixture was then
warmed up to 185◦C; the solid began to collapse and
became brown liquid gradually. After about 15 min,
the mixture became homogeneous solution. The re-
action was allowed to continue with stirring at that
temperature for another 5 min, followed by exposure
to air until the solution solidified completely at am-
bient temperature. The resulting white solid was re-
crystallized from 100 mL of water, affording 10.12 g
of colorless crystal. Yield 98.7%. mp 191◦C–192◦C
(lit. [33,34], mp 192◦C, yield 97%).
General Procedure for the Preparation of
N-Benzyloxycarbonyl-diphenyl-α-
aminophosphonates
To a 100-mL three-necked flask, triphenylphosphite
(31.0 g, 0.1 mol), aldehyde (0.12 mol), benzylcar-
bomate (15.3 g, 0.1 mol), and acetic acid (15 mL)
were added. The mixture was stirred at room tem-
perature for 1 h, then warmed to 80◦C–85◦C and
Heteroatom Chemistry DOI 10.1002/hc

60 Deng et al.
Compound 1,3-dihydro-1,3-dioxo-2H-isoindole-
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methyl(n-butyl) Phosphonate (5b). Yield 48%; mp
156◦C–158◦C; IR (KBr) (cm−1): 3278, 1775, 1723,
2-propanoic acid was prepared in a similar manner
with 98.4% yield, mp 153◦C–154◦C (lit. [33,34], mp
152◦C–153◦C).
1
3
1488; H NMR (CDCl3) δ: 0.93 (t, 3H, JH–H = 7.26
Hz, CH3), 1.32–1.47 (m, 2H, CH2CH2CH2CH3), 1.50–
1.72 (m, 2H, CH2CH2CH2CH3), 1.83–1.98 (m, 2H,
CH2CH2CH2CH3), 4.25 (m, 2H, CH2C O), 4.85 (t q,
Preparation of Phthalimidoacetyl Chloride (4)
3
3
2
To a 100-mL three-necked flask, phthalimidoacetic
acid (9.21 g, 0.045 mol) and thionyl chloride (15 mL)
were added in a sequence. The reaction mixture was
then warmed up to 60◦C and stirred for about 3 h.
The excess thionyl chloride was evaporated under
reduced pressure. Petroleum ether (30 mL) was sub-
sequently added and stirred, resulting in precipita-
tion of white solid. After filtration, the crude solid
was recrystallized from a mixture of benzene and
petroleum ether, affording pale yellow crystal. Yield
81.6%, mp 82◦C–84◦C (lit. [35], mp 83◦C–85◦C).
Phthalimidopropionyl chloride was prepared by
a similar manner and used immediately in the next
reaction. Yield 82.8%, mp 106◦C–107◦C (lit. [35], mp
107.5◦C–108◦C).
1H, JH–H = 3.22 Hz, JH–H = 6.58 Hz, JP–H = 17.02
Hz, CHP), 7.03 (br s, 1H, NH), 7.12–7.90 (m, 14H,
Harom); 13C NMR (CDCl3) δ: 14.2 (CH3), 19.3 (CH2),
33.4, 40.6, 45.2 (CH), 47.3 (CH2), 115.9, 119.4, 121.0,
123.6, 125.8, 129.6, 130.2, 132.5, 134.3, 150.4, 157.7
(O C), 167.3 (C O), 168.2 (NH C O); 31P NMR
(CDCl3) δ: 18.09.
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methylphenyl Phosphonate (5c). Yield 55%; mp
216◦C–218◦C; IR (KBr) (cm−1): 3298, 1776, 1723,
1
2
1488; H NMR (CDCl3) δ: 4.09 (d, 2H, JH–H = 16.65
Hz, NCH2), 5.95 (dd, 1H, 3 JH–H = 9.75 Hz,
2 JP–H = 21.72 Hz, CHP), 6.61–7.89 (m, 19H, Harom),
3
3
8.53 (dd, 1H, JP–H = 2.86 Hz, JH–H = 9.75 Hz,
NH); 13C NMR (CDCl3) δ: 49.8 (CH2), 51.9 (CH),
116.0, 121.0, 123.6, 125.9, 129.1, 129.8, 130.2,
132.4, 134.3, 150.5, 168.3 (O C), 170.2 (C O), 174.6
(NH C O); 31P NMR (CDCl3) δ: 14.71.
General Procedure for the Synthesis of
N-Blocked Phosphonodipeptides (5a–f) and
Homologs (6a–d)
A prepared solution of acid chloride 4 in THF
(30 mL) was added dropwise to an ice-cooled
solution of α-aminophosphonates 2 (1 equiv.) and
triethylamine (1.1 equiv.) in methylene chloride
(30 mL) over 15 min. The solution was then stirred
at ambient temperature overnight. After removal
of ammonium chloride by filtration, the solution
was concentrated on a rotavapor. The resulting
residue was dissolved in methylene chloride (40 mL),
washed with water, dried over sodium sulfate, fol-
lowed by filtration and evaporation. The obtained
residue was then crystallized from a mixture of
methylene chloride/diethyl ether (1/5, v/v), affording
white powder. Pure products 5a–f and 6a–d were ob-
tained by recrystallization from the same solvents.
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methyl(p-tolyl) Phosphonate (5d). Yield 68%; mp
213◦C–215◦C; IR (KBr) (cm−1): 3273, 1777, 1725,
1
1488; H NMR (CDCl3) δ: 2.28 (s, 3H, CH3), 4.03
2
(d, 2H, JH–H = 16.54 Hz, CH2C O), 5.82 (dd, 1H,
2
3 JH–H = 9.70 Hz, JP–H = 21.40 Hz, CHP), 6.60–7.81
3
(m, 18H, Harom), 8.98 (dd, 1H, JP–H = 3.01 Hz,
3 JH–H = 9.70 Hz, NH); 13C NMR (CDCl3) δ: 21.7
(CH3), 48.0 (CH2), 52.1 (CH), 120.9, 121.4, 123.9,
125.6, 126.1, 129.1, 129.9, 130.6, 131.1, 132.7, 134.4,
139.0, 150.6 (O C), 166.8 (C O), 168.0 (NH C O);
31P NMR (CDCl3) δ: 14.75.
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methyl(2,4-dichorophenyl) Phosphonate (5e). Yield
50%; mp 229◦C–231◦C; IR (KBr) (cm−1): 3271,
1779, 1724, 1488; 1H NMR (CDCl3) δ: 4.08 (d,
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methyl(p-methoxyphenyl) Phosphonate (5a). Yield
57%; mp 224◦C–226◦C; IR (KBr) (cm−1): 3274, 1775,
2
2H, JH–H = 16.53 Hz, CH2C O), 6.39 (dd, 1H,
2
3 JH–H = 9.30 Hz, JP–H = 22.72 Hz, CHP), 6.73–8.00
1
3
1719, 1515, 1488; H NMR (CDCl3) δ: 3.83 (s, 3H,
(m, 17H, Harom), 8.53 (dd, 1H, JP–H = 4.02 Hz,
2
CH3O), 4.08 (d, 2H, JH–H = 16.35 Hz, NCH2), 5.91
3 JH–H = 9.30 Hz, NH); 13C NMR (CDCl3) δ: 40.1
(CH2), 48.2 (CH), 115.9, 119.4, 120.4, 121.1, 123.6,
125.9, 126.3, 129.6, 130.1, 130.6, 131.5, 132.5,
134.4, 150.3 (O C), 157.7, 167.0, 168.0 (C O), 172.4
(NH C O); 31P NMR (CDCl3) δ: 22.72.
3
2
(dd, 1H, JH–H = 9.76 Hz, JP–H = 21.48 Hz, CHP),
3
6.65–7.89 (m, 18H, Harom), 8.54 (d, 1H, JH–H = 9.76
Hz, NH); 13C NMR (CDCl3) δ: 49.5 (CH2), 51.7, (CH),
55.8 (CH3), 114.8, 120.8, 121.2, 123.8, 125.6, 126.0,
129.9, 130.4, 132.6, 134.4, 150.5, 160.2 (C O CH3),
166.5 (C O), 168.0 (NH C O); 31P NMR (CDCl3) δ:
14.83.
Diphenyl(N-phthalimidomethylcarbonyl)amino-
methyl(o-nitrophenyl)phosphonate (5f). Yield 36%;
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of Phosphonodipeptide Conjugates of Ursolic Acid and Their Homologs 61
mp 186◦C–188◦C; IR (KBr) (cm−1): 3279, 1775,
150.3, 156.9 (O C), 168.4 (C O), 170.5 (NH C O);
31P NMR (CDCl3) δ: 14.56.
1
1722, 1532, 1488; H NMR (CDCl3) δ: 4.22 (d, 2H,
2 JH–H = 16.76 Hz, CH2C O), 7.48–7.68 (m, hidden
in aromatic protons’ peaks, 1H, CHP), 6.77–8.02
3
General Procedure for the Synthesis of
Phosphonodipeptides (7a–f) and Homologs (8a–d)
(m, 18H, Harom), 8.38 (dd, 1H, JP–H = 2.88 Hz,
3 JH–H = 9.44 Hz, NH); 13C NMR (CDCl3) δ: 40.1
(CH), 46.1, (CH2), 120.4, 120.9, 123.8, 126.3, 129.9,
130.4, 132.3, 134.6, 150.2, 167.5 (C O), 168.3
(NH C O); 31P NMR (CDCl3) δ: 13.24.
N-Blocked phosphonodipeptide 5a–f or homologs
6a–d (0.2 mmol) in anhydrous ethanol (5 mL)
were treated with hydrazine monohydrate (0.1 mL)
under nitrogen atmosphere at room temperature
overnight. The reaction ended up with some white
precipitate. After removal of the precipitate, the fil-
trate was concentrated on the rotavapor. After most
of solvent was removed, anhydrous THF (10 mL) was
subsequently added. The mixture was evaporated
again on the rotavapor (≤55◦C), followed by evapo-
ration on vacuum (oil pump), resulting in a colorless
sticky liquid. The obtained free amines were used in
the next reaction without further purification.
Diphenyl(N-phthalimidoethylcarbonyl)aminomethyl-
phenyl Phosphonate (6a). Yield 60%; mp 168◦C–
170◦C; IR (KBr) (cm−1): 3299, 1773, 1722, 1489;
1H NMR (CDCl3) δ: 2.57–2.64 (m, 2H, CH2C O),
3
3.94 (t, 2H, JH–H = 7.28 Hz, NCH2), 5.95 (dd, 1H,
2
3 JH–H = 9.88 Hz, JP–H = 20.80 Hz, CHP), 6.76–7.79
(m, 19H, Harom); 13C NMR (CDCl3) δ: 34.0 (CH2), 49.8
(CH2), 51.9 (CH), 116.0, 121.0, 123.6, 125.9, 129.1,
129.8, 130.2, 132.4, 134.3, 150.5, 168.3 (O C), 170.2
(C O), 174.6 (NH C O); 31P NMR (CDCl3) δ: 14.32.
Synthesis of 3β-Acetoxy-urs-12-en-28-oic Acid (9)
Diphenyl(N-phthalimidoethylcarbonyl)aminomethyl-
(o-chlorophenyl)Phosphonate (6b). Yield 44%; mp
174◦C–176◦C; IR (KBr) (cm−1): 3341, 1775, 1716,
1490; 1H NMR (CDCl3) δ: 2.50–2.56 (m, 2H,
CH2C O), 3.82–3.88 (m, 2H, NCH2), 5.82 (dd, 1H,
To a 50-mL flask, ursolic acid (0.1 g, 0.22 mmol),
pyridine (10 mL), acetic anhydride (2 mL), and
DMAP (0.027 g, 0.22 mmol) were added. The mixture
was kept stirring at room temperature under nitro-
gen for 2.5 h, then ground ice was added to the solu-
tion with stirring. After the ice dissolved completely,
the mixture was then extracted with methylene chlo-
ride (20 mL, 3 × 15 mL). The extracted organic phase
was combined and washed with water (5 × 20 mL).
The separated organic layer was further dried over
anhydrous sodium sulfate for 2 h, followed by filtra-
tion and evaporation under reduced pressure. The
residue was subject to azeotropic evaporation with
toluene (20 mL) on the rotavapor. After repetition
of addition and evaporation of toluene (four times),
the pale powder was obtained. Recrystallization of
crude solid from ethyl acetate/hexane (1/6, v/v) af-
forded a white solid with 97% yield, mp 289◦C–290◦C
(lit. [36,37], mp 288◦C–289◦C).
2
3 JH–H = 9.76 Hz, JP–H = 21.81 Hz, CHP), 6.70–7.75
(m, 18H, Harom), 8.85 (br s, 1H, NH); 13C NMR
(CDCl3) δ: 34.4 (CH2), 49.1 (CH2), 51.3 (CH), 120.6,
123.6, 125.8, 126.0, 129.4, 129.6, 130.3, 132.3, 133.0,
134.3, 150.6, 168.3 (C O), 170.0 (NH C O); 31P
NMR (CDCl3) δ: 13.73.
Diphenyl(N-phthalimidoethylcarbonyl)amino-
methyl(p-chlorophenyl) Phosphonate (6c). Yield
37%; mp 196◦C–198◦C; IR (KBr) (cm−1): 3278, 1780,
1
1717, 1489; H NMR (CDCl3) δ: 2.44–2.53 (m, 2H,
CH2C O), 3.78–3.87 (m, 2H, NCH2), 6.48 (dd, 1H,
2
3 JH–H = 9.43 Hz, JP–H = 22.28 Hz, CHP), 6.68–7.78
(m, 18H, Harom), 7.97 (br s, 1H, NH); 13C NMR
(CDCl3) δ: 33.8 (CH2), 34.6 (CH2), 48.4 (CH), 116.0,
120.3, 120.9, 123.5, 125.6, 126.0, 129.4, 129.6, 130.1,
132.3, 134.4, 150.5, 157.7 (O C), 168.3 (C O), 170.3,
175.3 (NH C O); 31P NMR (CDCl3) δ: 13.80.
Synthesis of 3β-Acetoxy-urs-12-en-28-oyl
Chloride (10)
Diphenyl(N-phthalimidoethylcarbonyl)aminomethyl-
(p-tolyl)Phosphonate (6d). Yield 55%; mp 158◦C–
160◦C; IR (KBr) (cm−1): 3333, 1775, 1717, 1489;
1H NMR (CDCl3) δ: 2.33 (s, 3H, CH3), 2.60 (m, 2H,
To a 10-mL flask, compound 9 (43 mg, 0.086 mmol)
and freshly distilled thionyl chloride (2 mL) were
added. The reaction was warmed to 65◦C and kept
stirring for about 5 h. The excess thionyl chlo-
ride was then removed under reduced pressure
at 50◦C–60◦C. Further evaporation on vacuum (oil
pump) provided a brown semisolid. The crude
solid was used in the next reaction without further
purification.
3
CH2C O), 3.94 (t, 2H, JH–H = 7.26 Hz, NCH2), 5.92
3
2
(dd, 1H, JH–H = 9.59 Hz, JP–H = 21.77 Hz, CHP),
6.75–7.78 (m, 18H, Harom); 13C NMR (CDCl3) δ: 21.0,
34.1 (CH2), 45.9 (CH2), 51.4 (CH), 115.3, 120.5,
123.3, 125.6, 128.5, 129.6, 130.6, 131.9, 134.2, 138.6,
Heteroatom Chemistry DOI 10.1002/hc

62 Deng et al.
3.51 (d, 1H,3 JH–H = 9.36 Hz, CH in 18), 3.45–4.04
(m, 2H, CH2C O), 4.06–4.17 (m, 1H, CHP), 4.41
(dd, overlapped, 1H, 3 JH–H = 8.04, 6.55 Hz, CH in 3),
5.33 (m, 1H, CH C), 6.64 and 6.66 (t, 1H, NHCH2,
3 JH–H = 4.13 Hz), 7.09–7.28 (m, 5H, Harom), 8.37 and
8.65 (br s, 1H, NH); 13C NMR (CDCl3) δ: 14.0, 15.8,
16.0, 16.8, 17.1, 17.6, 18.5, 21.7, 23.6, 23.7, 23.8,
28.1, 28.4, 29.7, 31.2, 32.1, 37.2, 38.0, 38.7, 39.4,
39.9, 40.1, 42.6, 47.8, 48.6, 54.2(C-18), 55.6 (C-5),
81.1 (C-3), 120.8, 125.3 (C-12), 126.1, 126.6, 130.0,
139.4 (C-13), 141.5, 150.8, 169.4 (O C O), 171.4
(NH C O), 179.1 (C-28); 31P NMR (CDCl3) δ: 21.74
General Procedure for the Preparation of
Phosphonodipeptide Conjugates of Ursolic Acid
(11a–f) and Homologs (12a–d)
To a 25-mL flask containing a solution of phospho-
nodipeptides 7a–f or homologs 8a–d (0.2 mmol) in
anhydrous THF (10 mL), triethylamine (0.3 mL)
and a newly prepared solution of acid chloride 10
(1 equiv.) in anhydrous THF (5 mL) over 10 min
at 0◦C were sequentially added. After completion of
addition, the reaction was allowed to continue at 0◦C
for 0.5 h and then at room temperature overnight.
The precipitate was filtered off, and the filtrate was
concentrated on the rotavapor. The residue was dis-
solved in dichloromethane (3 mL), and subsequently
separated by preparative thin layer chromatography
(25 × 25 cm2) using a mixture of ethyl acetate/hexane
(1/1, v/v) as eluent. The desired fraction (Rf = 0.2–
0.3) was collected and eluted with acetone. The sol-
vent was then evaporated under reduced pressure,
yielding the products 11a–f and 12a–d as sticky oils.
Yellow solid was obtained after standing for a couple
of days.
1
and 21.92. Anal. calcd for C H N O P· / H O: C,
2
45 69
2
7
2
68.41; H, 8.95; N, 3.55. Found: C, 68.38; H, 9.34; N,
3.63.
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethylphenyl)] Phosphonate
(11c). Yield 15%; pale yellow solid; mp 141◦C–
143◦C; IR (KBr) (cm−1): 3391, 2928, 1735, 1695,
1653, 1244, 1027; 1H NMR (CDCl3) δ: 0.57–1.96
(m, 42H, parent structure of ursolic acid unless
otherwise indicated), 1.98 (s, 3H, CH3), 3.50 (d, 1H,
3 JH–H = 9.86 Hz, CH in 18), 3.62–4.09 (m, 2H, CH2N),
4.42 (m, 1H, CH in 3), 5.23 and 5.24 (m, 1H, CH),
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethyl-p-methoxyphenyl)]
Phosphonate (11a). Yield 24%; Pale yellow solid;
mp 127◦C–129◦C; IR (KBr) (cm−1): 3393, 2929, 1735,
3
2
5.59 (dd, 1H, JH–H = 9.44 Hz, JP–H = 19.72 Hz,
CHP), 6.56 and 6.58 (br s, 1H, NH), 6.89–7.37 (m,
10H, Harom), 7.81 and 7.84 (br s, 1H, NHCH), 8.63
(br s, 1H, OH); 13C NMR (CDCl3) δ: 15.9, 16.5,
16.8, 17.1, 17.6, 18.5, 21.7, 23.6, 23.7, 23.9, 25.2,
28.2, 28.4, 30.1, 30.7, 31.2, 32.1, 37.1, 37.3, 38.0,
38.7, 39.3, 39.7, 39.9, 40.1, 42.6, 47.8, 48.1, 53.8,
54.2 (C-18), 55.5 (C-5), 81.2 (C-3), 120.8, 120.9,
125.5 (C-12), 126.6, 128.6, 129.1, 130.1, 134.7, 139.5
(C-13), 150.7, 169.1 (O C O), 171.4 (NH C O),
179.0, 179.5 (C-28); 31P NMR (CDCl3) δ: 18.04 and
1
1518, 1243, 1024; H NMR (CDCl3) δ: 0.56–1.98 (m,
43H, parent structure of ursolic acid unless other-
wise indicated), 2.05 (s, 3H, CH3C O), 3.42–3.74
(m, 1H, CH in 18), 3.80 (s, 3H, CH3O), 3.70–4.10
(m, 2H, CH2N), 4.45–4.52 (m, 1H, CH in 3), 5.35
3
and 5.39 (m, 1H, CH), 5.62 (dd, 1H, JH–H = 9.65
2
Hz, JP–H = 20.34 Hz, CHP), 6.65 and 6.70 (t, 1H,
3
NHCH2, JH–H = 4.8 Hz), 6.84–7.41 (m, 9H, Harom),
3
3
7.89 and 7.96 (dd, 1H, JH–H = 9.64 Hz, JP–H = 3.60
Hz, NHCH); 13C NMR (CDCl3) δ: 15.9, 16.5, 16.8,
17.1, 17.6, 18.5, 21.7, 23.6, 23.7, 23.9, 28.2, 28.4,
30.1, 31.2, 32.1, 37.1, 38.0, 38.6, 39.3, 39.7, 39.9,
40.1, 42.6, 47.8, 48.1, 53.9, 54.2 (C-18), 55.6 (C-5),
64.9 (O CH3), 81.2 (C-3), 114.5, 120.8, 120.9, 125.5
(C-12), 126.7, 129.9, 130.1, 139.4 (C-13), 150.8,
160.0, 169.0 (O C O), 171.4 (NH C O), 178.9,
179.4 (C-28); 31P NMR (CDCl3) δ: 18.30 and 18.42.
Anal. calcd for C48H67N2O8P·H2O: C, 67.90; H, 8.19;
N, 3.30. Found: C, 67.78; H, 8.05; N, 3.18.
1
18.18. Anal. calcd for C H N O P· / H O: C, 69.68;
2
47 65
2
7
2
H, 8.22; N, 3.46. Found: C, 69.75; H, 8.50; N, 3.16.
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethyl-p-tolyl)] Phosphonate
(11d). Yield 20%; pale yellow solid; mp 121◦C–
123◦C; IR (KBr) (cm−1): 3251, 2933, 1708, 1646,
1590, 1254, 1043; 1H NMR (CDCl3) δ: 0.57–1.95
(m, 43H, parent structure of ursolic acid unless
otherwise indicated), 1.97 (s, 3H, CH3C O), 2.25
3
(s, 3H, CH3), 3.47 (d, 1H, JH–H = 10.86 Hz, CH in
18), 3.73–4.01 (m, 2H, CH2C O), 4.40 (m, 1H, CH
in 3), 5.27 and 5.31 (m, 1H, CH), 5.56 (dd, 1H,
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethyl-N-butyl)] Phosphonate
(11b). Yield 16%; pale yellow solid; mp 102◦C–
103◦C; IR (KBr) (cm−1): 3395, 2925, 1737, 1656,
2
3 JH–H = 9.58 Hz, JP–H = 17.12 Hz, CHP), 6.57 and
6.62 (br s, 1H, NHCH2), 7.03–7.28 (m, 9H, Harom),
3
7.90 and 7.95 (d, 1H, JH–H = 9.57 Hz, NHCH),
1
1245, 1028; H NMR (CDCl3) δ: 0.59–1.97 (m, 52H,
8.36 (br s, 1H, OH); 13C NMR (CDCl3) δ: 15.9, 16.5,
16.8, 17.1, 17.6, 18.5, 21.6, 21.7, 23.1, 23.6, 23.7,
25.2, 28.2, 28.4, 30.1, 31.2, 32.3, 37.1, 37.3, 38.0,
CH2CH2CH2CH3 + parent structure of ursolic acid
unless otherwise indicated), 1.97 (s, 3H, CH3C O),
Heteroatom Chemistry DOI 10.1002/hc

Synthesis of Phosphonodipeptide Conjugates of Ursolic Acid and Their Homologs 63
38.6, 39.3, 39.7, 39.9, 40.0, 42.6, 47.8, 48.1, 53.8,
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
54.0 (C-18), 55.5 (C-5), 81.2 (C-3), 120.8, 121.0,
125.5 (C-12), 126.7, 128.5, 129.8, 130.1, 131.6, 139.4
(C-13), 150.8, 169.0 (O C O), 171.4 (NH C O),
179.0, 179.4 (C-28); 31P NMR (CDCl3) δ: 18.35 and
18.53. Anal. calcd for C48H67N2O7P·3H2O: C, 66.34;
H, 8.47; N, 3.22. Found: C, 66.47; H, 8.69; N, 3.64.
ethylcarbonyl)(aminomethylphenyl)]
Phosphonate
(12a). Yield 18%; pale yellow solid; mp 105◦C–
107◦C; IR (KBr) (cm−1): 3380, 2918, 1737, 1695,
1
1654, 1248, 1028; H NMR (CDCl3) δ: 0.59–1.96 (m,
43H, parent structure of ursolic acid unless other-
wise indicated), 1.98 (s, 3H, CH3C O), 3.04–3.46
(m, 2H, CH2C O), 3.49 (m, 1H, H-18), 3.51–3.92
3
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethyl-2,4-dichlorophenyl)]
Phosphonate (11e). Yield 14%; pale yellow solid;
mp 138◦C–140◦C; IR (KBr) (cm−1): 3375, 2923,
(m, 2H, CH2N), 4.37 and 4.40 (t, 1H, JH–H = 3.56
Hz, H-3), 5.09 and 5.14 (m, 1H, CH), 5.61 and 5.68
3
2
(dd, 1H, JH–H = 7.34 Hz, JP–H = 13.36 Hz, CHP),
6.37 and 6.48 (t, 1H, 3 JH–H = 6.02 Hz, NHCH2 minor
isomer), 7.04–7.44 (m, 11H, Harom, NHCH); 13C NMR
(CDCl3) δ: 15.9, 16.5, 17.1, 17.5, 18.5, 21.6, 21.7,
23.6, 23.9, 25.1, 28.1, 28.4, 30.1, 30.7, 31.2, 32.3,
33.0, 35.6, 37.1, 37.5, 37.6, 38.0, 38.6, 39.3, 39.9,
40.0, 42.6, 47.8, 48.0, 53.8, 54.0 (C-18), 55.6 (C-5),
65.0, 66.3, 81.3 (C-3), 115.7, 120.8, 125.6 (C-12),
126.3, 128.7, 129.2, 130.1, 134.8, 139.2 (C-13), 150.7,
169.1 (O C O), 171.5 (NH C O), 178.7 (C-28); 31P
NMR (CDCl3) δ: 18.69 and 18.76. Anal. calcd for
C48H67N2O7P: C, 70.74; H, 8.29; N, 3.44. Found: C,
70.50; H, 8.30; N, 3.39.
1
1737, 1660, 1369, 1244, 1024; H-NMR (CDCl3) δ:
0.59–1.92 (m, 43H, parent structure of ursolic acid
unless otherwise indicated), 1.94 (s, 3H, CH3C O),
3.43 (d, 1H,3 JH–H = 9.36 Hz, CH in 18), 3.50–3.96
(m, 2H, CH2C O), 4.36 (m, 1H, CH in 3), 5.28
3
(m, 1H, CH C), 6.10 (dd, 1H, JH–H = 7.88 Hz,
2 JP–H = 22.86 Hz, CHP), 6.60 and 6.91 (br s, 1H,
NHCH2), 7.08–7.40 (m, 8H, Harom), 7.67 and 7.80
(br s, 1H, NHCH), 8.59 (br s, 1H, OH); 13C NMR
(CDCl3) δ: 16.0, 16.5, 16.8, 17.1, 17.4, 17.7, 18.5,
21.6, 21.7, 23.6, 23.7, 23.9, 25.4, 26.0, 28.1, 28.4,
30.7, 31.2, 32.1, 33.0, 37.1, 37.4, 38.0, 38.7, 39.3,
39.5, 39.9, 40.1, 42.6, 43.1, 47.8, 48.1, 48.6, 53.9, 54.2
(C-18), 55.6 (C-5), 81.1 (C-3), 120.8, 120.9, 125.7
(C-12), 126.1, 127.9, 129.9, 130.7, 132.1, 135.2, 139.4
(C-13), 141.5, 150.8, 154.3, 169.0 (O C O), 171.4
(NH C O), 174.6, 179.5 (C-28); 31P NMR (CDCl3) δ:
16.86 and 16.98. Anal. calcd for C47H63Cl2N2O7P: C,
64.89; H, 7.30; N, 3.22. Found: C, 64.94; H, 7.24; N,
2.91.
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
ethylcarbonyl)(aminomethyl-o-chlorophenyl)] Phos-
phonate (12b). Yield 16%; pale yellow solid; mp
119◦C–121◦C; IR (KBr) (cm−1): 3385, 2927, 1734,
1
1656, 1243, 1022; H NMR (CDCl3) δ: 0.66–1.96 (m,
43H, parent structure of ursolic acid unless other-
wise indicated), 1.97 (s, 3H, CH3C O), 3.02–3.58
3
(m, 2H, CH2C O), 3.59 (d, 1H, JH–H = 9.86 Hz,
H-18), 3.60–4.14 (m, 4H, N–CH2–CH2), 4.40 (m, 1H,
H-3), 5.09 and 5.12 (m, 1H, H-12), 5.42 and 5.66
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
methylcarbonyl)(aminomethyl-o-nitro phenyl)] Phos-
phonate (11f). Yield 12%; yellow solid; mp 143◦C–
145◦C; IR (KBr) (cm−1): 3372, 2930, 1733, 1696,
3
2
(dd, 1H, JH–H = 9.44 Hz, JP–H = 22.26 Hz, CHP),
6.33 and 6.48 (br s, 1H, NHCH2), 7.08–7.38 (m, 9H,
Harom), 7.50 (br s, 1H, NHCH) 8.98 and 9.06 (br s,
1H, OH); 13C NMR (CDCl3) δ: 15.9, 16.4, 17.1, 17.5,
18.5, 21.6, 21.7, 23.6, 23.9, 25.1, 28.1, 28.4, 29.7,
30.1, 30.7, 31.1, 31.3, 33.0, 35.6, 35.8, 37.1, 37.6,
38.0, 38.6, 39.3, 39.9, 42.7, 47.8, 48.0, 53.2, 53.9,
54.0 (C-18), 55.6 (C-5), 65.0, 81.3 (C-3), 115.8, 120.8,
125.6 (C-12), 120.8, 125.8, 126.3, 129.3, 130.2, 139.4
(C-13), 150.7, 163.7 (O C O), 171.4 (NH C O),
178.6 (C-28); 31P NMR (CDCl3) δ: 17.98 and 21.52.
Anal. calcd for C48H66ClN2O7P·3H2O: C, 63.81; H,
8.03; N, 3.10. Found: C, 63.85; H, 8.26; N, 3.57.
1
1652, 1534, 1243, 1024; H NMR (CDCl3) δ: 0.60–
1.94 (m, 43H, parent structure of ursolic acid unless
otherwise indicated), 1.97 (s, 3H, CH3C O), 3.55–
4.15 (m, 3H, H-18, CH2C O), 4.41 (d t, overlapped,
3
1H, JH–H = 6.24, 6.05 Hz, CH in 3), 5.30 (m, 1H,
3
CH C), 6.70 and 6.78 (dd, 1H, JH–H = 6.08 Hz,
2 JP–H = 20.56 Hz, CHP), 6.90 and 6.93 (br s, 1H,
NHCH2) 7.01–7.99 (m, 9H, Harom), 8.06 (br s, 1H,
NHCH); 13C NMR (CDCl3) δ: 15.9, 16.3, 16.9, 17.1,
17.6, 18.5, 21.7, 23.7, 23.9, 25.2, 28.1, 28.4, 30.1,
31.2, 32.9, 37.1, 37.4, 38.0, 38.6, 39.3, 39.7, 39.9,
40.0, 42.6, 47.8, 48.1, 53.9, 54.2 (C-18), 55.6 (C-5),
66.2, 81.2 (C-3), 120.4, 120.9, 125.8 (C-12), 126.7,
129.3, 133.9, 130.1, 139.4 (C-13), 148.7, 150.6,
169.3 (O C O), 171.4 (NH C O), 179.4 (C-28);
31P NMR (CDCl3) δ: 16.30 and 16.97. Anal. calcd
for C47H64N3O9P·2H2O: C, 64.00; H, 7.77; N, 4.76.
Found: C, 64.05; H, 7.97; N, 4.52.
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
ethylcarbonyl)(aminomethyl-p-chlorophenyl)]Phospho-
nate (12c). Yield 11%; pale yellow solid; mp 125◦C–
127◦C; IR (KBr) (cm−1): 3400, 2926, 1735, 1657,
1
1534, 1243, 1026; H NMR (CDCl3) δ: 0.65–1.95 (m,
43H, parent structure of ursolic acid unless other-
wise indicated), 1.96 (s, 3H, CH2C O), 3.06–3.45
Heteroatom Chemistry DOI 10.1002/hc

64 Deng et al.
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(m, 2H, CH2C O), 3.56 (m, 1H, H-18), 3.60–3.90
(m, 2H, NCH2), 4.43 (m, 1H, H-3), 5.02 and 5.15 (m,
3
1H, H-12), 6.16 and 6.23 (dd, 1H, JH–H = 8.42 Hz,
2 JP–H = 19.75 Hz, CHP, minor isomer), 6.31 and 6.51
(br s, 1H, NHCH2), 7.08–7.52 (m, 9H, Harom), 7.55
(br s, 1H, NHCH, minor isomer), 8.92 and 9.04 (br
s, 1H,OH); 13C NMR (CDCl3) δ: 15.9, 16.3, 17.1, 17.3,
17.5, 18.5, 21.6, 21.7, 23.6, 23.7, 23.9, 25.1, 28.2,
28.4, 29.7, 30.1, 30.7, 31.1, 31.3, 32.1, 33.0, 35.3,
35.4, 37.1, 37.6, 38.1, 38.6, 39.3, 39.9, 42.6, 47.8,
48.0, 53.2, 53.8, 54.2 (C-18), 55.6 (C-5), 62.0, 65.0,
81.3 (C-3), 120.8, 125.7 (C-12), 126.4, 126.5, 127.6,
129.9, 130.1, 133.3, 133.5, 134.4, 134.6, 139.0, 139.4
(C-13), 150.7, 168.7 (O C O), 171.4 (NH C O),
178.6 (C-28); 31P NMR (CDCl3) δ: 18.12 and 18.15.
1
Anal. calcd for C H ClN O P· / H O: C, 67.15; H,
2
48 66
2
7
2
7.88; N, 3.26. Found: C, 67.24; H, 7.83; N, 3.28.
Phenyl[(N-3β-acetoxy-urs-12-en-28-oyl)(amino-
ethylcarbonyl)(aminomethyl-p-tolyl)] Phosphonate
(12d). Yield 8%; pale yellow solid; mp 126◦C–
128◦C; IR (KBr) (cm−1): 3400, 2922, 1736, 1647,
1
1243, 1026; H NMR (CDCl3) δ: 0.58–1.96 (m, 43H,
parent structure of ursolic acid unless otherwise
indicated), 1.97 (s, 3H, CH3C O), 2.10 (s, 3H, CH3),
3.03–4.20 (m, 5H, H-18, CH2C O, NCH2), 4.41 (m,
1H, H-3), 5.12 and 5.19 (m, 1H, H-12), 5.60 and 5.70
3
2
(dd, 1H, JH–H = 9.88 Hz, JP–H = 22.65 Hz, CHP),
3
6.38 and 6.52 (t, 1H, JH–H = 9.88 Hz, NHCH2),
7.06–7.31 (m, 10H, Harom, NHCH.), 8.90 and 9.34 (br
s, 1H, OH); 13C NMR (CDCl3) δ: 15.8, 16.4, 17.1, 17.3,
17.5, 18.5, 21.6, 21.7, 23.6, 23.9, 25.1, 28.2, 28.4,
29.7, 30.1, 30.7, 31.1, 31.3, 32.3, 33.0, 35.3, 35.4,
37.1, 37.6, 38.0, 38.6, 39.2, 39.9, 42.6, 47.8, 48.0,
54.0 (C-18), 55.5 (C-5), 64.9, 81.3 (C-3), 115.8, 120.9,
125.6 (C-12), 126.3, 128.6, 129.9, 130.1, 131.8, 138.6,
139.0, 139.3 (C-13), 150.9, 168.7 (O C O), 171.4
(NH C O), 178.6 (C-28); 31P NMR (CDCl3) δ: 18.75
and 22.21. Anal. calcd for C49H69N2O7P·3/2H2O: C,
65.97; H, 8.52; N, 3.14. Found: C, 66.07; H, 8.59; N,
3.56.
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Angres, G.; Scherf, H. R.; Wingen, F.; Amelung, F.;
Schmaehl, D. Cancer Treat Rev 1990, 17(2/3), 253–
259.
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