2-Azetidinone derivatives: Design, synthesis and evaluation of cholesterol absorption inhibitors

Article abstract of DOI:10.1016/j.ejmech.2008.09.033

Fourteen new derivatives of the 2-azetidinone cholesterol absorption inhibitors have been synthesized, and three of them were enantiomerically pure. All the new compounds were evaluated for their activity to inhibit cholesterol absorption in rats, and most of them showed comparable effects in lowering the levels of total cholesterol in the serum.

Full text of DOI:10.1016/j.ejmech.2008.09.033

European Journal of Medicinal Chemistry 44 (2009) 1638–1643
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
2-Azetidinone derivatives: Design, synthesis and evaluation of cholesterol
absorption inhibitors
,
b
a
c
Yubin Wang a, Huibin Zhang a, Wenlong Huang a , Jing Kong , Jinpei Zhou , Beibei Zhang
*
a New Drug Research Center, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
b Department of Pharmacology, China Pharmaceutical University, 24 Tongjiaxiang, Nanjing 210009, China
c Jiangsu Environmental Monitoring Center, 241 Fenghuangxijie, Nanjing 210036, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 April 2008
Received in revised form 5 September 2008
Accepted 5 September 2008
Available online 7 October 2008
Fourteen new derivatives of the 2-azetidinone cholesterol absorption inhibitors have been synthesized,
and three of them were enantiomerically pure. All the new compounds were evaluated for their activity
to inhibit cholesterol absorption in rats, and most of them showed comparable effects in lowering the
levels of total cholesterol in the serum.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords:
2-Azetidinone derivatives
Amide group
Cholesterol absorption inhibition
1. Introduction
cholesterol. Knockout mice lacking the NPC1L1 gene showed
markedly reduced cholesterol absorption and were no longer
Atherosclerotic coronary heart disease (CHD) has been the
major cause of death and cardiovascular morbidity in the world [1].
The prominent risk factor associated with CHD was the elevation of
serum cholesterol levels [2]. Well established clinical treatment for
CHD has focused on life style changes and the reduction of serum
cholesterol. These reductions have been shown to correlate
strongly with the decrease of CHD mortality and the reversal of
atherosclerosis as evidenced by the regression of occlusion of
coronary arteries [3]. Pharmacologically these reductions have
focused on the use of ‘‘statins’’ or HMG-CoA reductase inhibitors to
affect both the biosynthesis of cholesterol and clearance mecha-
nisms [4]. The other major contributor to serum cholesterol is from
exogenous (dietary) or intestinal sources (enterohepatic circulation
of biliary cholesterol). Blocking intestinal sources of cholesterol
sensitive to further reduction of cholesterol absorption by ezeti-
mibe. Thus NPC1L1 lies in the ezetimibe sensitive pathway for
cholesterol absorption, making it a likely candidate for the target of
ezetimibe [7].
The reported structure–activity relationships (SAR) studies
revealed that the 2-azetidinone was required for activity, the C-(3)
sidechain was optimal at three linking atoms bearing a pendent
aryl group and the C-(4) aryl residue was required and was opti-
mally substituted with a polar moiety at the para position, the N-
aryl ring was also required and was tolerant of a wide variety of
substitutions [8–10]. It is known that bioisosterism is an important
lead modification approach that has been shown to be useful to
attenuate toxicity or to modify the activity of a lead, and many have
a significant role in the alteration of pharmacokinetics of a lead. In
order to investigate the effect of the polarity of the C-(3) sidechain
on cholesterol absorption inhibition, we used bioisosteric inter-
change and introduced amide group to the C-(3) carbon chain in
compounds 2a–e, increasing the polarity of C-(3) sidechain. The
relative configuration at C-(3) and C-(4) of compounds 2a–e were
all trans. In order to acquire further insights into structure–activity
relationships (SAR), enantiomerically pure 2-azetidinone 4a–c
were also synthesized by using (S)-(þ)-4-phenyl-2-oxazolidinone.
The configuration at C-(3) and C-(4) of compounds 4a–c were all
(3R,4S). On the other hand, another chemical modification of 1 in
our research was aimed at investigating the hydrophobic require-
ments for their cholesterol absorption inhibition ability. Because
represents
a scientifically and pharmacologically interesting
mechanism for affecting serum cholesterol as it complements
existing therapies in the clinic [5].
Ezetimibe (1) (Fig. 1), which was approved in late 2002 for use
either alone or in combination with a statin, was the only example
to date of a drug that involves inhibition of intestinal cholesterol
absorption [6]. A recent report from the Schering-Plough Research
Institute has described the discovery of Niemann-Pick C1 Like 1
(NPC1L1) protein as critical for the intestinal absorption of
* Corresponding author. Tel./fax: þ86 25 83271480.
E-mail address: hktkcpu@126.com (W. Huang).
0223-5234/$ – see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.09.033

Y. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1638–1643
1639
OCH3
aromatic amine 6 in refluxing isopropyl alcohol gave imines 7.
Refluxing glutaric anhydride (8) with an equivalent amount of
anhydrous MeOH afforded monomethyl glutarate (9), and treat-
OH
F
O
OH
4
3
2
R3
N
H
N
N
1
ment of
9
in refluxing SOCl2 yielded methyl 4-(chlor-
O
F
O
oformyl)butyrate (10) in excellent yield 84.9% without further
purification. A preferred trans configuration of 2-azetidinone
intermediate 11 was established by modification of the ketene–
imine reaction. Compound 10 was added to a refluxing solution of
imine 7 in anhydrous toluene in the presence of tri(n-butyl)amine.
Maintaining the mixture refluxing overnight, gave 2-azetidinone
intermediate 11. Hydrolysis of 11 with LiOH solution affords acid 12
in almost quantitative yield. Finally the reaction of 12 with
substituted aromatic amine in the presence of DCC/DMAP in
anhydrous CH2Cl2 at room temperature gave 2-azetidinone deriv-
atives 2a–e in good yields (60.8–66.4%). In the 1H NMR spectra the
coupling constants between H-C(3) and H-C(4) of compounds 2a–e
were about 2 Hz, indicating that the relative configuration at C-(3)
and C-(4) of compounds 2a–e were all trans (J ¼ w2 Hz is charac-
teristic for trans-coupling between H-C(3) and H-C(4), whereas
J ¼ 5–6 Hz corresponds with the cis-configuration [11]).
R2
1
2a-e and
4a-c
OH
R3
R1
R3
N
O
R2
3a-f
Fig. 1.
hydrophobic forces may be the most important single factor
responsible for interaction between drug and receptor. Hydro-
phobicity could be increased by introducing another substituted
phenyl group to C-(3) carbon chain in 4a–c. In this way, the binding
of CAIs to their target protein may be enhanced and may be helpful
to their cholesterol absorption inhibition activity. As a result, the
ezetimibe analogs 2a–e, 3a–f and 4a–c (Fig. 1) were designed,
synthesized and their ability to inhibit cholesterol absorption was
evaluated.
Compounds 3a–f were obtained by reaction intermediate 11
with various Grignard reagents (Scheme 2). According to literature
[12], upon treatment of the b-lactam compound with aryl Grignard
reagents in ether as solvent at ꢀ40 ꢁC, the
b-lactam would be
opened by Grignard reagents (Fig. 2). But the expected open
product b-amino ketones 13 and b-amino carbibols 14 were not
2. Results and discussion
obtained in our research, even upon treatment with 4-fold excess of
Grignard reagents. The reaction invariably led to the corresponding
2.1. Chemistry
tertiary alcohols 3 and the starting
to the electronic features of substituents on the
atom. When electron withdrawing groups were connected to
nitrogen atom in 1-position of the -lactam ring, such as carbonyl
in Ref. [12], the -lactam ring could be easily opened by Grignard
reagents because of large ring strain in the four-membered ring.
While the substituent on the -lactam nitrogen was electron
donating, such as an aromatic ring, the -lactam ring was stable to
Grignard reagents, and the ester group in the 3-C sidechain was
able to react with Grignard reagents smoothly. Curiously, when the
same reaction was carried out in tetrahydrofuran as solvent, neither
the ring-opened product nor the ester-addition product was
obtained and the starting material was recovered unchanged. It
was unexpected that the solvent has such a dramatic effect on this
reaction.
b
-lactam 11. We attributed this
b-lactam nitrogen
The synthetic route to 2a–e is summarized in Scheme 1 [8].
Reaction of 4-methoxybenzaldehyde (5) with
a
substituted
b
b
OMe
NH2
CHO
b
b
a
HC
N
OMe
R2
d
R2
6
5
7
O
O
O
O
c
b
Cl
OMe
OH
OMe
In order to acquire further insights into structure–activity rela-
tionships (SAR), enantiomerically pure 2-azetidinone 4a–c were
also synthesized by using (S)-(þ)-4-phenyl-2-oxazolidinone. Our
synthesis of the enantiomerically pure 2-azetidinone analogs 4a–c
were based on an asymmetric synthesis of ezetimibe as depicted in
Scheme 3 [13]. Reactions of methyl 4-(chloroformyl)butyrate (10)
with (S)-(þ)-4-phenyl-2-oxazolidinone (15) in the presence of Et3N
in anhydrous CH2Cl2 at room temperature gave intermediate 16.
Then, 16 was treated with TiCl4, Hu¨nig’s base, and the corre-
O
O
O
10
9
8
OMe
OMe
O
O
e
MeO
HO
N
N
O
O
sponding imine 7 to give the intermediate b-aminoxazolidinone 17.
R2
R2
12
The major diastereomer was purified to homogeneity by crystalli-
zation and then cyclized in two steps by first silylation with bis-
trimethylsilylacetamide (BSA) followed by treatment with
a catalytic amount of tetrabutylammonium fluoride (TBAF) to get
a single enantiomerically pure intermediate 18. Then hydrolysis
and amidation of 18 led to enantiomerically pure 2-azetidinone
analogs 4a–c.
11
OMe
O
f
R3
N
H
N
O
2.2. Biological studies
R2
2a-e
Cholesterol absorption inhibition was assessed in orally dosed,
cholesterol-fed hamsters as reported in literature [14]. The result is
presented in the Table 1. As can be seen from the data, most of the
Scheme 1. Reagents and conditions: (a) iPrOH, reflux; (b) CH3OH, reflux; (c) SOCl2,
reflux; (d) n-Bu3N, toluene, reflux; (e) LiOH, THF/H2O, r.t.; (f) substituted aromatic
amine, DCC/DMAP, CH2Cl2, r.t.

1640
Y. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1638–1643
OMe
MeO
O
OH
O
O
R3
R1
R2
R1
R2
R1
R2
RMgBr
R3
MeO
N
HN
O
HN
O
11
R
3
13
14
OH
R3
RMgBr
R1
R2
R3
N
O
3a-f
Scheme 2. Reagents and conditions: R3MgBr, Et2O, reflux.
new compounds demonstrated moderate effect in lowering the
total cholesterol in serum, especially compound 4a and 4c,
although their potency was still somewhat below that of ezetimibe.
It was also found that 3c, 3d, 3e and 3f could raise high-density
lipoprotein cholesterol (HDL-C) levels markedly. This activity may
be good for prevention and treatment of CHD. The current work
suggests that the amide group in the C-(3) sidechain was not critical
for the cholesterol absorption inhibition activity and an increase of
compunds hydrophobicity may lead to the elevation of HDL-C.
These SAR trends may provide insights into the further design of
novel cholesterol absorption inhibitors.
mesh). Thin-layer chromatography (TLC): silica gel 60 F254 plates
(250 mm; Qingdao Ocean Chemical Company, China). M.p.: capil-
lary tube; uncorrected. IR spectra: Shimadzu FTIR-8400S spectro-
photometer; in cmꢀ1. 1H NMR spectra: Bruker ACF-300Q apparatus
at 300 MHz, in CDCl3 unless otherwise indicated;
d in ppm rel. to
Me4Si, J in Hz. Mass spectrometry (MS): Hewlett–Packard 1100 LC/
MSD spectrometer; in m/z. Elemental analyses: CHN-O-Rapid
instrument.
4.1.2. General procedure for the preparation of 2a–e
A mixture of the appropriate 4-methoxybenzaldehyde (5)
(10 mmol) and substituted aromatic amine 6 (10 mmol) in iso-
propanol (40 mL) was heated to reflux, cooled to room tempera-
ture, and diluted with hexanes and allowed to stand overnight. The
resulting precipitate was collected via vacuum filtration, washed
with cold hexanes and dried under vacuum to give imines 7.
Refluxing glutaric anhydride (8) (0.44 mol) with equivalent anhy-
drous methanol (30 mL) affords monomethyl glutarate (9) and then
treatment of 9 in refluxing SOCl2 (100 mL) gave methyl 4-(chlor-
oformyl)butyrate (10) (0.37 mol) in good yield (84.9%) without
further purification. Compound 10 (77 mmol) was added to
refluxing solution of imine 7 (38 mmol) in anhydrous toluene
(150 mL) in the presence of n-tributylamine (114 mmol). The
mixture was heated to reflux overnight, cooled to room tempera-
ture, 1 M HCl was added, the resulting mixture was stirred for
15 min, transferred to a separatory funnel, diluted with ethyl
acetate, washed with 1 M HCl, NaHCO3(satd), water and brine,
dried over anhydrous sodium sulfate, and concentrated to an oil.
The resulting oil was loaded onto a chromatography column pre-
packed with silica gel and 20% ethyl acetate/hexane. Elution with
the same solvent provided trans 2-azetidinone intermediate 11.
Lithium hydroxide (0.82 g, 19.6 mmol) was dissolved in water
(20 mL) and added to a room temperature solution of trans 2-
azetidinone intermediate 11 (16.3 mmol) in THF (60 mL). After 6 h,
the reaction was quenched with HCl (1 M), transferred to a sepa-
ratory funnel, diluted with ethyl acetate, washed with HCl (1 M),
water and brine, dried over anhydrous sodium sulfate, and
concentrated to give acid 12 of sufficient purity to be used without
further purification. To a stirring solution of acid 17 (5 mmol), 4-
dimethylaminopyridine (0.25 mmol) and substituted aromatic
amine (5.5 mmol) in dry CH2Cl2 (40 mL) under N2 was added
dicylohexylcarbodimide (5.5 mmol). The mixture was stirred at
room temperature for 36 h and the solids were filtered. The filtrate
was concentrated in vacuum and the residue was chromatographed
(15% ethyl acetate/hexane). Initially target compounds 2a–e were
obtained.
3. Conclusions
In an effort to understand the SAR around cholesterol absorp-
tion inhibition, fourteen 2-azetidinone derivatives were synthe-
sized and their cholesterol absorption inhibition activities were
evaluated. Most of them showed comparable effects in lowering the
levels of total cholesterol in the serum. These information could be
valuable for further investigation of SAR and will be useful in later
research of cholesterol absorption inhibitors.
4. Experimental
4.1. Chemistry
4.1.1. General
All reagents were purchased from Shanghai Chemical Reagent
Company. Column chromatography (CC): silica gel 60 (200–300
OBn
O
RMgX
R
O
THF, -40¡ã1h
,
O
NHBoc
O
H
H
N
O
BnO
O
Boc
RMgX
OBn
O
R
O
THF, rt,1h
R
OH NHBoc
Fig. 2.

Y. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1638–1643
1641
O
heated to reflux. After 12 h, H2O and H2SO4 (2 N, 75 ml) were added,
separated the layers and washed the organic layer sequentially with
NaOH (10%), NaCl (satd) and water. Dried the organic layer over
MgSO4 and concentrated to obtain solid product 16. To a solution of
TiCl4 (3 ml, 27.5 mmol) in CH2Cl2 (100 ml) at ꢀ10 ꢁC added
compound 16 (8.2 g, 28.3 mmol) as a solution in CH2Cl2 (50 ml).
After 5 min. added diisopropylethylamine (DIPEA) (11 ml, 61 mmol)
and stirred at ꢀ20 ꢁC. for 1 h. Cooled the reaction mixture to ꢀ35 ꢁC,
and added imine 7 (61 mmol) as a solid. Stirred the reaction vigor-
ously for 4 h. at ꢀ30 ꢁC. Added acetic acid as a soln. in CH2Cl2
dropwise over 15 min., allowed the reaction to warm to 0 ꢁC and
added H2SO4 (2 N). Stirred the reaction an additional 1 h, separated
the layers, washed with water, separated and dried the organic
layer. Crystallized the crude from ethanol to obtain the pure inter-
mediate 17. To a solution of 17 (7.5 mmol) in toluene (50 mL) at 60 ꢁC
added N,O-bis(trimethylsilyl)acetamide (BSA) (3.6 ml, 15.2 mmol)
and stirred the reaction at 60 ꢁC. for an additional 3 h. Cooled the
reaction mixture to room temperature, added CH3OH (5 ml),
washed the reaction mixture with HCl (1 N), NaHCO3(1 N) and NaCl
(satd), dried the organic layer over MgSO4, and concentrated to an
oil. The resulting oil was loaded onto a chromatography column
prepacked with silica gel and 20% ethyl acetate/hexane. Elutionwith
the same solvent provided a single enantiomerically pure inter-
mediate 18. Lithium hydroxide (0.82 g, 19.6 mmol) was dissolved in
water (20 ml) and added to a room temperature solution of enan-
tiomerically pure intermediate 18 (16.3 mmol) in THF (60 ml). After
6 h, the reaction was quenched with HCl (1 M), transferred to
a separatory funnel, diluted with ethyl acetate, washed with HCl
(1 M), water and brine, dried over anhydrous sodium sulfate, and
concentrated to give acid 18 of sufficient purity to be used without
further purification. To a stirring solution of acid 18 (5 mmol), 4-
dimethylaminopyridine (0.25 mmol) and substituted aromatic
amine (5.5 mmol) in dry CH2Cl2 (40 mL) under N2 was added
dicyclohexylcarbodimide (5.5 mmol). The mixture was stirred at
room temperature for 36 h and the solids were filtered. The filtrate
was concentrated in vacuum and the residue was chromatographed
(15% ethyl acetate/hexane). Initially target compounds 4a–c were
obtained.
O
Cl
O
O
O
a
O
HN
Ph
H3CO
N
O
OMe
b
Ph
O
16
15
10
H3CO
C
H
N
R2
7
R2
OMe
O
O
O
HN
d
c
MeO
O
N
N
O
OMe
Ph
R2
OMe
O
18
17
OMe
OMe
O
O
e
R3
N
HO
H
N
N
O
O
R1
R2
4a-c
19
Scheme 3. Reagents and conditions: (a) Et3N, CH2Cl2, r.t.; (b) TiCl4, DIPEA, CH2Cl2, ꢀ30
to ꢀ40 ꢁC;(c) BSA, TBAF, toluene, 40–50 ꢁC; (d) LiOH, THF/H2O, r.t.; (e) 4-methylaniline,
DCC/DMAP, CH2Cl2, r.t.
4.1.3. General procedure for the preparation of 3a–f
Compound 11 (5 mmol) resolved in 150 ml ether was added to
refluxing Grignard reagents R3MgBr (12.5 mmol). The mixture was
refluxing for 12 h, cooled to room temperature, 1 M HCl was added,
transferred to a separatory, diluted with ethyl acetate, washed with
NaHCO3 (satd), water and brine, dried over anhydrous sodium
sulfate, and concentrated to oil. The resulting oil was loaded onto
a chromatography column prepacked with silica gel and 10% ethyl
acetate/hexane. Initially target compounds 3a–f were obtained.
4.1.4. General procedure for the preparation of 4a–c
4.1.5. Trans-N-(4-Methylphenyl)-3-(3-[2-oxo-4-(4-methoxypheyl)-
1-(4-methoxyphenyl)-azetidinyl])propanamide (2a)
Yield: 43.2%. Yellow crystals, m.p. 56–57 ꢁC. IR (KBr): 3494,
2930, 1731, 1715, 1512, 1295, 1247, 1173, 1030. 1H NMR (CDCl3): 2.39
(s, 3H, –CH3), 2.26–2.45 (m, 2H, –CH2–CH2–), 2.62 (t, J ¼ 7.2 Hz, 2H,
(S)-4-phenyl-2-oxazolidinone (15) (20 g, 0.12 mol) in CH2Cl2
(20 ml) was added 4-dimethylaminopyridine (1.2 g, 0.01 mol) and
Et3N (42.3 ml, 0.31 mol) and cooled the reaction to 0 ꢁC. Then,
a solution of methyl 4-(chloroformyl)butyrate (10; 20 g, 0.12 mol) in
CH2Cl2 (150 ml) was added dropwise over 1 h and the mixture was
Table 1
Cholesterol absorption inhibition of new analogs and reference compounds in orally dosed seven-day cholesterol-fed hamsters.
Compounda
R1
R2
R3
TCb (% reduction)
HDL-Cc (% increase)
2a
2b
2c
2d
2e
3a
3b
3c
3d
3e
3f
4a
4b
4c
Ezetimibe
–
–
–
–
MeO
H
Me
CH3
Cl
CH3
Cl
H
H
H
F
F
F
Me
CH3
Cl
20.9
NEd
26.3*
18.7
16.3
28.7*
34.8**
16.3
10.4
11.2
19.8
28.1*
NE
12.4
13.9
17.8
23.9
20.1
11.4
CH3
CH3
MeO
4-Cl
6-Me
4-F
6-Me
4-Br
4-OMe
MeO
H
–
3,4-Dioxolmethylene
4-OMe
4-OMe
3,4-Dioxolmethylene
14.5
35.0**
24.8
32.9**
31.8**
21.7
22.1
13.7
37.3**
4-OMe
3,4-Dioxolmethylene-6-bromo-
–
–
–
–
CH3
–
31.6*
48.7**
–
**P < 0.01; *P < 0.05.
a
6–8 Hamsters per group; dose: 50 mg/kg.
b
c
Reduction of total cholesterol comparing to the one in animals fed by high-cholesterol diets.
Increase of HDL-C comparing to the one in animals fed by high-cholesterol diets.
NE: no effect.
d

1642
Y. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1638–1643
–CH2–CH2–), 3.09–3.11 (m, 1H, –CH–CH–), 3.74 (s, 6H, –OCH3), 4.66
(d, J ¼ 2.3 Hz, 1H, –CHN–), 6.80 (dd, J ¼ 8.4, 17.9 Hz, 4H, Ar-H), 7.21–
7.27 (m, 4H, Ar-H), 7.32–7.36 (m, 4H, Ar-H), 7.79 (s, 1H, –NH–CO–);
MS: 445.2 ([M þ H]þ); Anal. calc. for C27H28N2O4 (444.21): C 72.95,
H 6.35, N 6.30; found: C 72.70, H 6.60, N 5.92.
(s, 3H, –OCH3), 4.69 (d, J ¼ 2.4 Hz, 1H, –CHN–), 6.83–7.07 (m, 4H, Ar-
H), 7.20–7.27 (m, 5H, Ar-H), 7.30–7.34 (m, 5H, Ar-H), 7.39–7.46 (m, 4H,
Ar-H); MS: 500.3 ([M þ Na]ꢂþ); Anal. calc. for: C32H31NO3 (477.23): C
80.23, H 6.69, N 2.81; found: C 80.47, H 6.54, N 2.93.
4.1.12. Trans-1-(4-Fluorophenyl)-3-(3-hydroxy-3,3-
4.1.6. Trans-N-(4-Methylphenyl)-3-(3-[2-oxo-4-(4-methoxyphenyl)-
1-phenyl-azetidinyl])propanamide (2b)
diphenylpropyl)-4-(4-methoxyphenyl)-2-azetidinone (3c)
Yield: 36.4%. White crystals, m.p.157–159 ꢁC. IR (KBr): 3436,1720,
1510, 1389, 1249, 827, 704; 1H NMR (CDCl3): 1.85–1.94 (m, 2H,
–CH2CH2–), 2.56–2.62 (m, 2H, –CH2CH2–), 3.07–3.13 (m,1H, –CHCH–
), 3.81 (s, 3H, –OCH3), 4.50 (d, J ¼ 2.1 Hz, 1H, –CHN–), 6.88–6.91 (m,
4H, Ar-H), 7.19–7.28 (m, 5H, Ar-H), 7.30–7.33 (m, 5H, Ar-H), 7.39–7.43
(m, 4H, Ar-H); MS: 504.1 ([M þ Na]ꢂþ); Anal. calc. for: C32H28FNO3
(481.21): C 77.61, H 5.63, N 2.74; found: C 77.32, H 5.86, N 2.91.
Yield: 46.9%. White crystals, m.p. 102–103 ꢁC. IR (KBr): 3328,
2916, 2848, 2635, 1624, 1467, 1378, 1308, 1243, 1088; 1H NMR
(CDCl3): 2.31 (s, 3H, –CH3), 2.39–2.46 (m, 2H, –CH2–CH2–), 2.60–
2.65 (m, 2H, –CH2–CH2–), 3.07–3.13 (m, 1H, –CH–CH–), 3.78 (3H, s,
–OCH3), 4.69 (d, J ¼ 2.1 Hz, 1H, –CHN–), 7.01–7.05 (m, 4H, Ar-H),
7.09–7.17 (m, 5H, Ar-H), 7.28–7.45 (m, 4H, Ar-H), 7.83 (1H, s, –NH–
CO–); MS: 453.1 ([M þ K]þ); Anal. calc. for: C26H26N2O3 (414.13): C
75.34, H 6.32, N 6.76; found: C 74.89, H 6.48, N 6.74.
4.1.13. Trans-1-(6-Methylphenyl)-3-(3,3-bis(4-fluorophenyl)-3-
hydroxypropyl)-4-(benzo[d][1,3]dioxol-5-yl)-2-azetidinone (3d)
Yield: 21.4%. White crystals, m.p. 89–91 ꢁC. IR (KBr): 3449, 1732,
1446, 1245, 1037, 833, 752; 1H NMR (CDCl3): 1.87–1.92 (m, 2H,
–CH2CH2–), 2.37 (s, 3H, –CH3), 2.59–2.68 (m, 2H, –CH2CH2–), 2.72 (s,
1H, -OH), 3.15–3.16 (m,1H, –CHCH–), 4.65 (d, J ¼ 2.1 Hz,1H, –CHN–),
5.93 (s, 2H, –OCH2O–), 6.74–6.76 (m, 3H, Ar-H), 6.97–7.03 (m, 4H,
Ar-H), 7.07–7.15 (m, 4H, Ar-H), 7.35–7.40 (m, 4H, Ar-H); MS: 550.2
([M þ Na]ꢂþ); Anal.calc. for: C32H27F2NO4 (527.19): C 72.64, H 5.47, N
2.71; found: C 72.85, H 5.16, N 2.66.
4.1.7. Trans-N-(4-Chlorophenyl)-3-(3-[2-oxo-4-(4-methoxyphenyl)-
1-(4-methylphenyl)-azetidinyl])propanamide (2c)
Yield: 35.8%. Yellow oil. IR (KBr): 3518, 3331, 2901, 2548, 1888,
1755, 1613, 1537, 1392, 1249, 1176, 1089, 1033; 1H NMR (CDCl3): 2.24
(s, 3H, –CH3), 2.26–2.43 (m, 2H, –CH2–CH2–), 2.61–2.67 (m, 2H,
–CH2–CH2–), 3.08–3.15 (m, 1H, –CH–CH–), 3.77 (s, 3H, –OCH3), 4.88
(d, 1H, J ¼ 2.2 Hz, –CHN–), 7.08–7.16 (m, 4H, Ar-H), 7.18–7.29 (m, 4H,
Ar-H), 7.40–7.49 (m, 4H, Ar-H), 9.60 (1H, br, –NH–CO–); MS: 449.3
([M þ H]þ); Anal. calc. for C26H25ClN2O3 (448.16): C 69.18, H 5.94, N
6.30; found: C 69.56, H 5.61, N 6.24.
4.1.14. Trans-1-(4-Bromophenyl)-3-(3,3-bis(4-fluorophenyl)-3-
hydroxypropyl)-4-(4-methoxyphenyl)-2-azetidinone (3e)
Yield: 19.9%. White crystals, m.p. 122–124 ꢁC. IR (KBr): 3429,
1750, 1609, 1489, 1250, 1071, 827; 1H NMR (CDCl3): 1.85–1.87 (m,
2H, –CH2CH2–), 2.47 (s, 1H, –OH), 2.51–2.59 (m, 2H, –CH2CH2–),
3.09–3.10 (m, 1H, –CHCH–), 3.80 (s, 3H, –OCH3), 4.50 (d, J ¼ 2.4 Hz,
1H, –CHN–), 6.88–6.91 (m, 4H, Ar-H), 6.99–7.14 (m, 4H, Ar-H), 7.21–
7.33 (m, 4H, Ar-H), 7.35–7.38 (m, 4H, Ar-H); MS: 601.0 ([M þ Na]ꢂþ);
Anal. calc. for: C31H26BrF2NO3 (577.11): C 67.9, H 4.27, N 2.49; found:
C 64.37, H 4.53, N 2.42.
4.1.8. Trans-N-(4-Methylphenyl)-3-(3-[2-oxo-4-(4-methoxyphenyl)-
1-(4-methylphenyl)-azetidinyl])propanamide (2d)
Yield: 36.6%. Yellow oil. IR (KBr): 3848, 2900, 1742, 1600, 1513,
1442, 1392, 1249, 1065; 1H NMR (CDCl3): 2.29 (s, 6H, –CH3), 2.27–
2.44 (m, 2H, –CH2–CH2–), 2.62–2.67 (m, 2H, –CH2–CH2–), 3.06–3.12
(m, 1H, –CH–CH–), 3.77 (s, 3H, –OCH3), 4.66 (d, J ¼ 2.3 Hz, 1H,
–CHN–), 7.11–7.16 (m, 4H, Ar-H), 7.15–7.27 (m, 4H, Ar-H), 7.35–7.46
(m, 4H, Ar-H), 7.98 (s, 1H, –NH–CO–); MS: 429.3 ([M þ H]þ); Anal.
calc. for C27H28N2O3 (428.21): C 75.93, H 6.27, N 6.49; found: C
75.68, H 6.59, N 6.54.
4.1.15. Trans-1-(4-Methoxyphenyl)3-(3,3-bis(4-fluorophenyl)-
3-hydroxypropyl)-4-(6-bromobenzo[d][1,3]dioxol-5-yl)-2-
azetidinone (3f)
4.1.9. Trans-N-(4-Chlorophenyl)-3-(3-[2-oxo-4-(4-methoxyphenyl)-
1-(4-methoxyphenyl)-azetidinyl])propanamide (2e)
Yield: 21.5%. Yellow crystals, m.p. 104–106 ꢁC. IR (KBr): 3487,
1720, 1510, 1240,1034, 930, 830; 1H NMR (CDCl3): 1.93–1.99 (m, 2H,
–CH2CH2–), 2.47–2.54 (m, 2H, –CH2CH2–), 3.02 (d, J ¼ 2.1 Hz, 1H,
–CHCH–), 3.76 (s, 3H, –OCH3), 5.00 (d, J ¼ 2.1 Hz, 1H, –CHN–), 5.95
(s, 2H, –OCH2O–), 6.80–6.83 (m, 2H, Ar-H), 6.96–7.04 (m, 4H, Ar-H),
7.15–7.18 (m, 4H, Ar-H), 7.35–7.39 (m, 4H, Ar-H); MS: 644.1/646.2
([M þ Na]ꢂþ); Anal. calc. for: C32H26BrF2NO5 (622.45): C 72.64, H
5.47, N 2.71; found: C 61.75, H 4.21, N 2.25.
Yield: 43.7%. Yellow crystals, m.p. 58–59 ꢁC. IR (KBr): 3501, 2923,
1731, 1666, 1613, 1512, 1395, 1298, 1246, 1173, 1089, 1029; 1H NMR
(CDCl3, 300 M): 2.19–2.25 (m, 2H, –CH2–CH2–), 2.61–2.68 (m, 2H,
–CH2–CH2–), 3.05–3.11 (m, 1H, –CH–CH–), 3.70 (s, 6H, –OCH3), 4.65
(d, J ¼ 2.3 Hz, 1H, –CHN–), 6.84–7.05 (m, 4H, Ar-H), 7.09–7.17 (m,
4H, Ar-H), 7.30–7.42 (m, 4H, Ar-H), 8.16 (s, 1H, –NH–CO–); MS:
465.3 ([M þ H]þ); Anal. calc. for: C26H25ClN2O4 (464.15): C 67.17, H
5.42, N 6.03; found: C 66.95, H 5.38, N 5.96.
4.1.16. (3R,4S)-N-(4-Methylphenyl)-(3-[2-oxo-4-
4.1.10. Trans-1-(4-Chlorophenyl)-3-(3-hydroxy-3,3-
(4-methoxyphenyl)-1-(4-methoxyphenyl)-azetidinyl])
propanamide (4a)
diphenylpropyl)-4-(benzo[d][1,3]dioxol-5-yl)-2-azetidinone (3a)
Yield: 33.7%. White crystals. m.p.148–150 ꢁC. IR (KBr): 3461,
1742, 1492, 1447, 1390, 1246, 1040, 702; 1H NMR (CDCl3): 1.85–1.98
(m, 2H, –CH2CH2–), 2.35–2.70 (m, 2H, –CH2CH2–), 3.04–3.18 (m, 1H,
–CHCH–), 4.46 (d, J ¼ 2.1 Hz, 1H, –CHN–), 5.97 (s, 2H, –OCH2O–),
6.75–6.80 (m, 3H, Ar-H), 7.19–7.29 (m, 5H, Ar-H), 7.30–7.35 (m, 5H,
Ar-H), 7.39–7.42 (m, 4H, Ar-H); MS: 534.3 ([M þ Na]ꢂþ); Anal. calc.
for: C31H26ClNO4 (511.16): C 72.51, H 5.39, N 2.96; found: C 72.72, H
5.12, N 2.74.
Yield: 22.7%. Yellow oil. IR (KBr): 3316, 2923, 1728, 1599, 1537,
1511, 1249, 1110, 834; 1H NMR (CDCl3): 2.31 (s, 3H, –CH3), 2.24–2.30
(m, 2H, –CH2–CH2–), 2.59–2.64 (m, 2H, –CH2–CH2–), 3.09–3.14 (m,
1H, –CH–CH–), 3.78 (s, 6H, –OCH3), 4.66 (d, J ¼ 2.0 Hz, 1H, –CHN–),
6.76–6.85 (m, 4H, Ar-H), 7.19–7.27 (m, 4H, Ar-H), 7.28–7.40 (m, 4H,
Ar-H), 7.79 (s, 1H, –NH–CO–); MS: 445.4 ([M þ H]þ); Anal. calc. for
C27H28N2O4 (444.20): C 72.73, H 6.49, N 6.41; found: C 72.95, H
6.35, N 6.30.
4.1.11. Trans-1-(6-Methylphenyl)-3-(3-hydroxy-3,3-
4.1.17. (3R,4S)-N-(4-Methylphenyl)-3-(3-[2-oxo-4-(4-
diphenylpropyl)-4-(4-methoxyphenyl)-2-azetidinone (3b)
Yield: 35.1%. White oil. IR (KBr): 3384, 1727, 1514, 1252, 1029, 749,
701; 1H NMR (CDCl3): 1.92–1.96 (m, 2H, –CH2CH2–), 2.44 (s, 3H,
–CH3), 2.64–2.69(m, 2H, –CH2CH2–), 3.15–3.21 (m,1H, –CHCH–), 3.77
methoxyphenyl)-1-phenyl-azetidinyl])propanamide (4b)
Yield: 19.1%. White crystals, m.p. 115–117 ꢁC. IR (KBr): 3332,
2927, 1737, 1669, 1598, 1513, 1386, 1249, 1178, 1033, 818, 754, 691;
1H NMR (CDCl3): 2.31 (s, 3H, –CH3), 2.22–2.27 (m, 2H, –CH2–CH2–),

Y. Wang et al. / European Journal of Medicinal Chemistry 44 (2009) 1638–1643
1643
2.60–2.65 (m, 2H, –CH2–CH2–), 3.11–3.16 (m,1H, –CH–CH–), 3.78 (s,
3H, –OCH3), 4.69 (d, J ¼ 2.1 Hz,1H, –CHN–), 6.83–7.05 (m, 4H, Ar-H),
7.09–7.17 (m, 5H, Ar-H), 7.28–7.45 (m, 4H, Ar-H), 7.69 (s, 1H, –NH–
CO–); MS: 453.3 ([M þ K]þ); Anal. calc. for: C26H26N2O3 (414.19): C
75.39, H 6.31, N 6.79; found: C 74.89, H 6.48, N 6.74.
(mid-light cycle) during this time period. On the last day the
animals were sacrificed and blood sample was taken for lipid
analyses. Plasma cholesterol levels and HDL-C levels were deter-
mined by a commercial modification of the cholesterol oxidase
method which was available in a kit form.
4.1.18. (3R,4S)-N-(4-Chlorophenyl)-3-(3-[2-oxo-4-(4-
Acknowledgements
methoxyphenyl)-1-(4-methylphenyl)-azetidinyl])propanamide (4c)
Yield: 23.6%. Yellow oil. IR (KBr): 2924, 2868, 1728, 1598, 1537,
1512, 1246, 1236, 1108, 823. 1H NMR (CDCl3): 2.23 (s, 3H, Me), 2.25–
2.39 (m, 2H, –CH2–CH2–), 2.60–2.65 (m, 2H, –CH2–CH2–), 3.08–3.13
(m, 1H, –CH–CH–), 3.76 (s, 3H, MeO), 4.63 (d, J ¼ 2.1, 1H, –CHN–),
6.82–6.89 (m, 4H, Ar-H), 7.02–7.14 (m, 4H, Ar-H), 7.21–7.27 (m, 4H,
Ar-H), 8.35 (s, 1H, –NH–CO–); MS: 471.3 ([M þ Na]þ). Anal. calcd for
C26H25N2O3Cl (448.16): C 69.85, H 5.43, N 6.57; found: C 69.56, H
5.61, N 6.24.
This work was sported by Jiangsu Graduate Student Innovation
Foundation (No.: xm04-74).
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