Unsymmetrically disubstituted urea derivatives: A potent class of antiglycating agents

Article abstract of DOI:10.1016/j.bmc.2009.01.075

A series of unsymmetrically disubstituted urea derivatives 1-28 has been synthesized and screened for their antiglycation activity in vitro. Compounds 26 (IC₅₀ = 4.26 ± 0.25 μM), 1 (IC₅₀ = 5.8 ± 0.08 μM), 22 (IC₅₀ = 4.26 ± 0.25 μM), 6 (IC₅₀ = 6.4 ± 0.02 μM), 5 (IC₅₀ = 6.6 ± 0.26 μM), 2 (IC₅₀ = 7.02 ± 0.31 μM), 3 (IC₅₀ = 7.14 ± 0.84 μM), 27 (IC₅₀ = 7.27 ± 0.36 μM), 4 (IC₅₀ = 8.16 ± 1.04 μM), 21 (IC₅₀ = 8.4 ± 0.15 μM), 23 (IC₅₀ = 9.0 ± 0.35 μM) and 13 (IC₅₀ = 15.22 ± 6.7 μM) showed an excellent antiglycation activity far better than the standard (rutin, IC₅₀ = 41.9 ± 2.3 μM). This study thus provides a series of potential molecules for further studies of antiglycation agents.

Full text of DOI:10.1016/j.bmc.2009.01.075

Bioorganic & Medicinal Chemistry 17 (2009) 2447–2451
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Unsymmetrically disubstituted urea derivatives: A potent class
of antiglycating agents
b
a
b
b
a
Khalid M. Khan a, , Sumayya Saeed , Muhammad Ali , Madiha Gohar , Javariya Zahid , Ambreen Khan ,
*
Shahnaz Perveen c, M. Iqbal Choudhary a
a HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
b Department of Chemistry, University of Karachi, Karachi 75270, Pakistan
c PCSIR Laboratories Complex Karachi, Shahrah-e-Dr. Salim-uz-Zaman, Karachi 75280, Pakistan
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of unsymmetrically disubstituted urea derivatives 1–28 has been synthesized and screened for
Received 24 November 2008
Revised 30 January 2009
Accepted 31 January 2009
Available online 9 February 2009
their antiglycation activity in vitro. Compounds 26 (IC50 = 4.26 0.25
l
M), 1 (IC50 = 5.8 0.08
M), (IC50 = 7.02 0.31
M), 21 (IC50 = 8.4 0.15
M) showed an excellent antiglycation activity far better
l
l
l
M), 22
M),
M), 23
(IC50 = 4.26 0.25
(IC50 = 7.14 0.84
l
l
M),
6
(IC50 = 6.4 0.02
l
l
M),
5
(IC50 = 6.6 0.26
l
l
2
3
M), 27 (IC50 = 7.27 0.36
M), 4 (IC50 = 8.16 1.04
(IC50 = 9.0 0.35
l
M) and 13 (IC50 = 15.22 6.7
l
than the standard (rutin, IC50 = 41.9 2.3
further studies of antiglycation agents.
l
M). This study thus provides a series of potential molecules for
Keywords:
Unsymmetrically disubstituted urea
Antiglycation
Ó 2009 Published by Elsevier Ltd.
Substituent effects
Lead compounds
1. Introduction
NOÅ production in lipopolysaccharide-activated macrophages were
evaluated.10
Urea is a functional moiety that is commonly found in natural
products and often displays a wide range of biological activities.1
In particular; substituted ureas have attracted attention due to
their range of applications as agricultural pesticides,2 dyeing mate-
rial for hair and cellulose fibres, antioxidants in gasoline and addi-
tives in detergents to prevent carbon deposits and corrosion
inhibitors.3 They can also serve as uron herbicides,1,2 plant growth
regulators, agroprotectives, tranquillizers and as anticonvulsants.3
An unsymmetrically substituted urea is a common structural fea-
ture of many biologically active compounds such as enzyme inhib-
itors and pseudopeptides.4 Unsymmetrically substituted ureas at
amino groups have also been shown to have a potent HIV-1 prote-
ase inhibitory activity,3,4 equipotent towards both wild and mutant
types.4 Sulfonylureas have found applications as oral antidiabetic
drugs and as herbicides.5 Some urea derivatives are useful as active
ingredients in antimicrobial, antifungal and algaecides agents.6
Among them diaryl urea derivatives have been patented for
treatment of protein kinase dependent diseases of the animal or
human body.7
In the present study in vitro antiglycation effect of a series of
unsymmetrically disubstituted urea derivatives 1–28 was evalu-
ated. Discovery of antiglycation agents is now considered to be
an important area of pharmaceutical research for the treatment
of late diabetic complications.
The incident of type-2 diabetes is increasing at an alarming rate
and about 1–2% of the world’s population is affected with over 100
million diabetic patients are worldwide. A large number of studies
focused the factors involving in the pathogenesis of diabetic
complications but the exact molecular basis of these complications
is not fully understood yet. Hyperglycemia is one of the causative
factors of diabetes complications, that is, atheroma, hypertension
and microangiopathy. Its detrimental effects are mostly attributed
to the formation of sugar-derived substances called advanced
glycation end products (AGEPs).11 AGEPs are a group of molecules
formed in a non-enzymatic way from combination of reducing
sugars with free amino groups of proteins, lipids and nucleic
acids. An enormous amount of evidence suggests that AGEPs are
significant pathogenic mediators of almost all increasing diabetic
complications.12
Some novel urea derivatives found to be useful for the
treatment of inflammatory diseases.8,9 A series of ureas and
thioureas was synthesized, and their inhibitory activities against
Initial product of protein–glucose interaction is Schiff base
which forms without any enzyme, whereas the rearrangement of
Schiff base intermediate to Amadori product takes number of days.
Extent of glycation of vital biochemicals is dependent on the
degree and duration of hyperglycemia in vivo. Considerable effort
* Corresponding author. Tel.: +92 214824910; fax: +31204852799.
E-mail addresses: khalid.khan@iccs.edu, hassaan2@super.net.pk (K.M. Khan).
0968-0896/$ - see front matter Ó 2009 Published by Elsevier Ltd.
doi:10.1016/j.bmc.2009.01.075

2448
K. M. Khan et al. / Bioorg. Med. Chem. 17 (2009) 2447–2451
H
N
H
N
has been focussed on the discovery of new inhibitors of glycation
because of their therapeutic potential.13 Antiglycating compounds
may react with carbonyl group of reducing sugars, Amadori prod-
ucts and 3-deoxyglucosones to inhibit the formation of AGEPs. Cer-
tain molecules have been developed that can cleave AGEP cross-
links and perhaps open the possibility of reversing the steady pro-
cess of diabetic complications.14 Antioxidants may provide protec-
tion against glycation-derived free radicals, while chelators are
helpful in removing the transition metals to prevent autoxidation
of glucose and Amadori products.15
Compounds with both antiglycation and antioxidant properties
may offer therapeutic potential. It has been found that aged garlic
extract (AGE) inhibit the formation of AGEPs in vitro and it also
prevents the formation of glycation-derived free radicals. S-Allyl-
cysteine is a key component of aged garlic extract that acts as a po-
tent antioxidant and may inhibit the AGEPs formation.16
R
R
N C O
R
CH Cl , 0 ºC
30 min
+
R -NH
O
1-28
S. No.
1
R
R
Yield (%) S. No.
R
R
Yield (%)
CH3
OCH3
CH3
Cl
55
91
52
60
15
16
17
18
H
81
CH3
2
3
4
Cl
Cl
Cl
H
H
H
88
57
83
H3CO
CH3
CH3
OCH3
Br
H3C
CH3
Aminoguanidine, an inhibitor of AGEP formation was found to
prevent retinopathy in diabetic animals and protect them from
developments of diabetic vascular complications. However, amino-
guanidine has encountered some toxicity problems in phase III of
clinical trials so this drug can serve as a prototype for many new
molecules that are being synthesized and tried in vitro at pres-
ent.17 Efforts have now been intensely dedicated to the search of
new and safe synthetic antiglycation agents.18 It has been demon-
strated that polyamines, spermine and spermidine have potent
antiglycation effects. Results of protection against glycation were
comparable to those of aminoguanidine and carnosine.19
CH3
CH3
5
Cl
77
19
H
50
Br
CH3
OCH3
6
7
Cl
Cl
84
86
20
21
H
H
85
32
Br
CH3
CH3
CH3
OCH3
Br
8
9
Cl
Cl
94
26
22
23
H
H
63
41
2. Results and discussion
2.1. Chemistry
CH3
CH3
CH3
CH3
CH3
We have previously reported the tertiary amine promoted syn-
thesis of symmetrical 1,3-disubstituted ureas in high yields.20 In
the present study we prepared a series of twenty-eight (28)
unsymmetrical N,N0-disubstituted aryl urea 1–28 by reacting
substituted phenyl isocyanates with respective amines in dichloro-
methane at 0 °C for 30 min, as shown in Scheme 1. In all experi-
ments, solid materials were formed which were filtered, washed
with minimum amount of ethanol, dried under vacuum and
recrystallized with ethanol. The structures of compounds were
confirmed by using 1H NMR and mass spectroscopy.
CH3
Cl
Cl
10 Cl
96
87
24
25
H
H
32
66
CH3
CH3
11 Cl
Br
H3C
Br
CH3
CH3
12 Cl
13 Cl
84
47
26
27
H
H
33
22
2.2. Biology
Cl
Cl
NO2
All the synthesized compounds 1–28 were randomly evaluated
for their antiglycation activity according to literature protocol.21
Unsymmetrical N,N0-disubstituted ureas 1–28 exhibited a varying
degree of antiglycation activity, when compared to standard rutin
NO2
NO2
14
Cl
61
28
H
53
H3CO
H3CO
(IC50 = 41.9 2.3
0.25 M), 1 (IC50 = 5.8 0.08
(IC50 = 6.4 0.02 M), 5 (IC50 = 6.6 0.26
M), 3 (IC50 = 7.14 0.84 M), 27 (IC50 = 7.27 0.36
M), 21 (IC50 = 8.4 0.15 M), 23 (IC50 = 9.0 0.35
l
M) (Table 1). Compounds 26 (IC50 = 4.26
M), 22 (IC50 = 4.26 0.25 M), 6
M), 2 (IC50 = 7.02 0.31
Scheme 1. Synthesis of unsymmetrically disubstituted urea derivatives.
l
l
l
l
l
l
l
lM), 4 (IC50
=
8.16 1.04
l
l
l
M)
of the aromatic rings has pronounced effect in glucose or protein
and 13 (IC50 = 15.22 6.7
activities, far better than standard (rutin, IC50 = 41.9 2.3
The compounds with IC50 values more than 100 M were consid-
ered to be inactive. Additionally compounds 7, 8, 10–12 and 15–
19 initially showed less than 50% activity and thus were not further
evaluated for their IC50. Compound 26 having a bromine moiety
meta to urea bond found to be the most active among the series
l
M) showed excellent antiglycation
binding activity. Compound 27 having a nitro group at its meta po-
lM).
sition showed an IC50 value 7.27 0.36
21 having para methoxy and 23 containing meta and para dimethyl
groups showed IC50 values 8.4 0.15 and 9.0 0.35 M, respec-
lM, whereas compounds
l
l
tively. These results also showed that a suitable substituent at aro-
matic ring is responsible for enhancing the glucose or protein
binding ability of the molecule.
with an IC50 value 4.26 0.25
exhibited an IC50 value 6.1 0.13
logue 25 showed an IC50 value 120.4 14.6
activity of different analogues reveals that the substitution at one
l
M, however, its para analogue 22
M, surprisingly the ortho ana-
M. This difference in
In chloro-containing unsymmetrical urea derivatives, com-
pound 1 having a methoxy group at meta position of the second
aromatic ring was found to be active with an IC50 value of
l
l
5.8 0.08 lM, however, its ortho 2 and para 3 analogues showed

K. M. Khan et al. / Bioorg. Med. Chem. 17 (2009) 2447–2451
2449
Table 1
3.1. Materials and methods
Anti-glycation activities of the compounds 1–28
Bovine serum albumin (BSA) was purchased from Research
Organics, Cleveland, while other chemicals, glucose anhydrous, tri-
chloroacetic acid (TCA), sodium azide (NaN3), dimethyl sulfoxide
(DMSO), sodium dihydrogen phosphate (NaH2PO4), sodium chlo-
ride (NaCl), disodium hydrogen phosphate (Na2HPO4), potassium
chloride (KCL), potassium dihydrogen phosphate (KH2PO4) and so-
dium hydroxide (NaOH) were purchased from Sigma Aldrich.
Sodium phosphate buffer (pH 7.4) was prepared by mixing
Na2HPO4 (67 mM) containing sodium azide (3 mM), phosphate
buffer saline (PBS) was prepared by mixing NaCl (137 mM) + Na2H-
PO4 (8.1 mM) + KCl (2.68 mM) + KH2PO4 (1.47 mM) and pH 10 was
adjusted with NaOH (0.25 mM), while BSA (10 mg/mL) and anhy-
drous glucose (50 mg/mL solutions were prepared in sodium phos-
phate buffer.
Compounds
IC50 SEM (
lM)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
5.8 0.08
7.02 0.31
7.14 0.84
8.16 1.04
6.6 0.26
6.4 0.02
Inactive
Inactive
905.9 3.8
Inactive
Inactive
Inactive
15.22 6.7
407.6 1.7
Inactive
Inactive
17
18
Inactive
Inactive
3.2. Anti-glycation assay (in vitro)21
19
Inactive
20
21
22
23
24
25
26
27
229 11.8
8.4 0.15
6.1 0.13
In 96-well plate assays, each well contain 60
tures {20 L bovine serum albumin (BSA) (10 mg/mL + 20
glucose anhydrous (50 mg/mL) + 20 L, test sample}. Glycated con-
trol contains 20 L BSA + 20 L glucose + 20 L sodium phosphate
buffer, while blank control contains 20 L BSA and 40 L sodium
phosphate buffer. Reaction mixture was incubated at 37 °C for 7-
days. After incubation, 6 L (100%) of trichloroacetic acid (TCA)
l
L of reaction mix-
l
l
L of
l
9
0.35
l
l
l
838.3 3.14
120.4 14.6
4.26 0.25
7.27 0.36
162.5 16.8
41.9 2.3
l
l
l
28
was added in each well and centrifuged (15,000 rpm) for 4 min
Rutin (std.)
at 4 °C. After centrifugation, the pellets were rewashed with
60
and interfering substance was removed and pellet containing ad-
vance glycated end product (AGE)-BSA were dissolved in 60
phosphate buffer solution (PBS). Assessment of fluorescence spec-
trum (excitation 370 nm), and change in fluorescence intensity
(excitation 370 nm to emission 440 nm), based on AGEs were mon-
itored by using spectrofluorimeter (RF-1500, Shimadzu, Japan); %
inhibition was calculated through the following formula:
lL (10%) of TCA. The supernatant containing glucose, inhibitor
slightly higher IC50 values 7.02 0.31, and 7.14 0.84
l
M, respec-
lL
tively. Para bromo-containing compound 6 demonstrated an IC50
value 6.4 0.02 M, whilst its meta analog 4 showed an IC50
8.16 1.04 M also indicating that the presence of suitable substi-
l
=
l
tuent(s) on both or either of the aromatic ring of unsymmetrically
disubstituted ureas are assisting factors in glucose or protein bind-
ing affinity. When a compound 13 having meta and para dichloro
groups was screened, it showed an IC50 value 15.22 6.7 lM,
which clearly demonstrated that disubstitution may result in low-
ering of antiglycation activity.
% Inhibition ¼ ½1 ꢀ ðFluorescence of sample=Fluorescence
of glycated sampleÞ ꢁ 100ꢂ
In conclusion, compounds 26 (IC50 = 4.26 0.25
5.8 0.08 M), 26 (IC50 = 4.26 0.25 M), 22 (IC50 = 6.1 0.13
M), 6 (IC50 = 6.4 0.02 M), 5 (IC50 = 6.6 0.26 M), 2 (IC50
7.02 0.31 M), 3 (IC50 = 7.14 0.84 M), 27 (IC50 = 7.27 0.36
M), (IC50 = 8.16 1.04 M), 21 (IC50 = 8.4 0.15 M), 23
(IC50 = 9.0 0.35 M) and 13 (IC50 = 15.22 6.7 M) showed excel-
lent antiglycation activities, far better than standard (rutin,
IC50 = 41.9 2.3 M). These compounds therefore, may serve as
lM), 1 (IC50 =
l
l
3.3. General procedure for preparation of N,N0-(disubstituted)-
urea 1–28
l
l
l
=
l
l
l
4
l
l
l
l
Aniline (0.184 mL, 1.66 mmol) was dissolved in 5 mL dichloro-
methane. Temperature was maintained at 0 °C, then substituted
phenyl isocyanate (0.20 mL, 1.65 mmol) was added drop wise with
constant stirring. After 30 min, formation of white solid was oc-
curred and the resultant solid product was filtered, washed with
little ethanol and dried under vacuum. Recrystallization with eth-
anol afforded the desired solid urea.
l
powerful lead compounds for further studies.
3. Experimental
Melting points were determined on Gallenkamp melting point
apparatus and are uncorrected. Analytical thin-layer chromatogra-
phy (TLC) was performed on pre-coated silica gel plates (Kieselgel
60 F254, E. Merck, Germany) and chromatograms were visualized
under UV light at 254 and 365 nm or iodine vapors. Solvents for
extraction and chromatography were of reagent grade. Solvents
used for chemical reactions were distilled before use. 1H NMR
spectroscopy was performed on a Bruker AVANCE 300, 400 MHz
and 500 MHz, d in ppm related to SiMe4 (0 ppm) as internal stan-
dard. Mass spectra were recorded either on MAT-312 or on JEOL
JMS-HX 110 instruments. All the biological screenings were done
in laboratories of the H. E. J. Research Institute of Chemistry, Inter-
national Center for Chemical and Biological Sciences, University of
Karachi, Karachi 75270, Pakistan.
3.3.1. N-(3-Chlorophenyl)-N0-(3-methoxyphenyl)-urea (1)
Yield: 0.25 g, 55%; Rf = 0.67 (CH2Cl2/MeOH, 9.5:0.5); mp:
185 °C; 1H NMR: (500 MHz, DMSO-d6): d 8.82 (s, 1H, N–H), 8.71
(s, 1H, N–H), 7.69 (s, 1H, Ar-H), 7.27 (m, 2H, Ar-H), 7.17 (m, 2H,
Ar-H), 7.0 (d, 1H, J = 8.0 Hz, Ar-H), 6.92 (d, 1H, J = 8.0 Hz, Ar-H),
6.55 (d, 1H, J = 6.3 Hz, Ar-H), 3.72 (s, 3H, OCH3); EI MS: m/z (rel.
abund. %), 278 (M2+, 26.9), 276 (M+, 83), 155 (19.4), 153 (56.8),
149 (46.8), 129 (31.7), 127 (100), 123 (65.1), 119 (10).
3.3.2. N-(3-Chlorophenyl)-N0-(2-methoxyphenyl)-urea (2)
Yield: 0.52 g, 91%; Rf = 0.87 (CH2Cl2/MeOH, 9.5:0.5); mp:
158 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.49 (s, 1H, N–H), 8.25
(s, 1H, N–H), 8.09 (d, 1H, J = 6.2 Hz, Ar-H), 7.72 (s, 1H, Ar-H), 7.10

2450
K. M. Khan et al. / Bioorg. Med. Chem. 17 (2009) 2447–2451
(m, 6H, Ar-H), 3.87 (s, 3H, OCH3); EI MS: m/z (rel. abund. %), 278
(M2+, 32.7), 276 (M+, 100), 155 (4.7), 153 (11.7), 149 (18.1), 129
(28), 127 (100), 123 (98), 108 (74.2).
(s, 1H, N–H), 7.74 (s, 1H, Ar-H), 7.62 (s, 1H, Ar-H), 7.26 (m, 2H,
Ar-H), 7.03 (m, 2H, Ar-H), 6.79 (d, 1H, J = 7.7 Hz, Ar-H), 2.24 (s,
3H, CH3), 2.17 (s, 3H, CH3); EI MS: m/z (rel. abund. %), 274 (M+,
46), 276 (M2+, 15.8), 153 (33.4), 155 (11.3), 147 (52.9), 129
(43.7), 127 (100), 121 (82.9), 106 (27.8).
3.3.3. N-(3-Chlorophenyl)-N0-(4-methoxyphenyl)-urea (3)
Yield: 0.30 g, 52%; Rf = 0.64 (CH2Cl2/MeOH, 9.5:0.5); mp:
176 °C; 1H NMR: (500 MHz, DMSO-d6): d 8.76 (s, 1H, N–H), 8.50
(s, 1H, N–H), 7.68 (s, 1H, Ar-H), 7.34 (d, 2H, J = 8.9 Hz, Ar-H), 7.25
(m, 2H, Ar-H), 6.83 (d, 1H, J = 7.6 Hz, Ar-H), 6.86 (d, 2H, J = 8.6 Hz,
3.3.11. N-(3-Chlorophenyl)-N0-(2,6-dimethylphenyl)-urea (11)
Yield: 0.50 g, 87%; Rf = 0.71 (CH2Cl2/MeOH, 9.5:0.5); mp:
218 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.95 (s, 1H, N–H), 7.79
(s, 1H, N–H), 7.26 (s, 1H, Ar-H), 7.01 (m, 6H, Ar-H), 2.19 (s, 6H,
CH3); EI MS: m/z (rel. abund. %), 274 (M+, 20.5), 276 (M2+, 9.9),
153 (5.5), 147 (19), 127 (100), 121 (50.7), 106 (20.8).
Ar-H), 3.71 (s, 3H, OCH3); EI MS: m/z (rel. abund. %), 278 (M2+
,
32.7), 276 (M+, 95.7), 155 (4.6), 153 (13.5), 149 (49.8), 129 (18.5),
127 (55.6), 123 (100), 108 (91.4).
3.3.4. N-(3-Bromophenyl)-N0-(3-chlorophenyl)-urea (4)
3.3.12. N-(3-Chlorophenyl)-N0-(3,4-dimethylphenyl)-urea (12)
Yield: 0.48 g, 84%; Rf = 0.76 (CH2Cl2/MeOH, 9.5:0.5); mp:
200 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.81 (s, 1H, N–H), 8.54
(s, 1H, N–H), 7.70 (s, 1H, Ar-H), 7.22 (m, 6H, Ar-H), 2.18 (s, 3H,
CH3), 2.14 (s, 3H, CH3); EI MS: m/z (rel. abund. %), 274 (M+, 57.8),
276 (M2+, 19.7), 155 (14.3), 153 (42.5), 147 (76.1), 132 (57.1),
127 (100), 121 (93.4), 106 (34.1).
Yield: 0.41 g, 60%; Rf = 0.80 (CH2Cl2/MeOH, 9.5:0.5); mp:
235 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.95 (s, 1H, N–H), 8.94
(s, 1H, N–H), 7.83 (s, 1H, Ar-H), 7.69 (s, 1H, Ar-H), 7.19 (m, 6H,
Ar-H); EI MS: m/z (rel. abund. %), 326 (M+, 12.24), 328 (M2+
,
3.08), 171 (54.1), 173 (51.7), 127 (100), 129 (36.5), 92.1 (45.7),
65.1 (55.7).
3.3.5. N-(2-Bromophenyl)-N0-(3-chlorophenyl)-urea (5)
3.3.13. N-(3-Chlorophenyl)-N0-(3,4-chlorophenyl)-urea (13)
Yield: 0.31 g, 47%; Rf = 0.74 (CH2Cl2/MeOH, 9.5:0.5); mp:
196 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.09 (s, 1H, N–H), 9.04
(s, 1H, N–H), 7.86 (d, 1H, J = 2.4 Hz, Ar-H), 7.68 (s, 1H, Ar-H), 7.52
(d, 1H, J = 8.7 Hz, Ar-H), 7.32 (m, 3H, Ar-H), 7.03 (m, 1H, Ar-H); EI
MS: m/z (rel. abund. %), 274 (M+, 57.8), 276 (M2+, 19.7), 155
(14.3), 153 (42.5), 147 (76.1), 132 (57.1), 127 (100), 121 (93.4),
106 (34.1).
Yield: 0.52 g, 77%; Rf = 0.93 (CH2Cl2/MeOH, 9.5:0.5); mp:
189 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.64 (s, 1H, N–H), 8.18
(s, 1H, N–H), 8.03 (d, 1H, J = 8.2 Hz, Ar-H), 7.73 (s, 1H, Ar-H), 7.62
(d, 1H, J = 8.0 Hz, Ar-H), 7.30 (m, 3H, Ar-H), 7.00 (m, 2H, Ar-H); EI
MS: m/z (rel. abund. %), 326 (M+, 9), 328 (M2+, 2.2), 245 (38), 171
(77.3), 173 (74), 127 (100), 129 (33.3), 92.1 (54), 65.1 (60.6).
3.3.6. N-(4-Bromophenyl)-N0-(3-chlorophenyl)-urea (6)
Yield: 0.57 g, 84%; Rf = 0.77 (CH2Cl2/MeOH, 9.5:0.5); mp:
209 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.91 (s, 1H, N–H), 8.89
(s, 1H, N–H), 7.68 (s, 1H, Ar-H), 7.43 (m, 4H, Ar-H), 7.28 (m, 2H,
Ar-H), 7.01 (m, 1H, Ar-H); EI MS: m/z (rel. abund. %), 326 (M+,
20), 328 (M2+, 5.2), 197 (7.3), 199 (7.4), 171 (100), 173 (7.85),
127 (97), 129 (36.2), 92.1 (63.1), 65.1 (71.4).
3.3.14. N-(3-Chlorophenyl)-N0-(2-methoxy-5-nitrophenyl)-urea
(14)
Yield: 0.45 g, 61%; Rf = 0.76 (CH2Cl2/MeOH, 9.5:0.5); mp:
203 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.63 (s, 1H, N–H), 9.08
(s, 1H, N–H), 8.63 (s, 1H, Ar-H), 7.93 (d, 1H, J = 7.8 Hz, Ar-H), 7.73
(s, 1H, Ar-H), 7.25 (m, 3H, Ar-H), 7.05 (d, 1H, J = 7.8 Hz, Ar-H),
4.03 (s, 3H, OCH3); EI MS: m/z (rel. abund. %), 321 (M+, 19.5), 323
(M2+, 5.9), 194 (66.2), 168 (95), 153 (89.4), 155 (24.7), 127 (100),
129 (30.8).
3.3.7. N-(3-Chlorophenyl)-N0-(2,3-dimethylphenyl)-urea (7)
Yield: 0.49 g, 86%; Rf = 0.87 (CH2Cl2/MeOH, 9.5:0.5); mp:
196 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.10 (s, 1H, N–H), 8.01
(s, 1H, N–H), 7.72 (s, 1H, Ar-H), 7.47 (d, 1H, J = 8.0 Hz, Ar-H), 7.26
(m, 2H, Ar-H), 6.97 (m, 3H, Ar-H), 2.44 (s, 3H, CH3), 2.12 (s, 3H,
3.3.15. N-(2,3-Dimethylphenyl)-N0-phenyl-urea (15)
Yield: 0.36 g, 81%; Rf = 0.96 (CH2Cl2/MeOH, 9.5:0.5); mp:
190 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.89 (s, 1H, N–H), 7.91
(s, 1H, N–H), 7.52 (d, 1H, J = 8.0 Hz, Ar-H), 7.43 (d, 2H, J = 7.9 Hz
Ar-H), 7.25 (t, 2H, J = 7.8 Hz Ar-H), 6.95 (t, 1H, J = 7.7 Hz, Ar-H),
6.94 (d, 1H, J = 7.3 Hz, Ar-H), 6.89 (t, 1H, J = 7.4 Hz, Ar-H), 2.24 (s,
3H, CH3), 2.12 (s, 3H, CH3); EI MS: m/z (rel. abund. %), 240 (M+,
74.3), 147 (12.9), 106 (25.9), 93 (100).
CH3); EI MS: m/z (rel. abund. %), 274 (M+, 93.2), 276 (M2+
,
32.2), 153 (12.4), 147 (20.3), 129 (33.8), 127 (100), 121 (52.7),
106 (21.3).
3.3.8. N-(3-Chlorophenyl)-N0-(2,4-dimethylphenyl)-urea (8)
Yield: 0.43 g, 94%; Rf = 0.87 (CH2Cl2/MeOH, 9.5:0.5); mp:
215 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.11 (s, 1H, N–H), 7.90
(s, 1H, N–H), 7.72 (s, 1H, Ar-H), 7.59 (d, 1H, J = 8.1 Hz, Ar-H), 7.25
(m, 2H, Ar-H), 7.69 (m, 3H, Ar-H), 2.22 (s, 3H, CH3), 2.18 (s, 3H,
3.3.16. N-(2,4-Dimethylphenyl)-N0-phenyl-urea (16)
Yield: 0.39 g, 88%; Rf = 0.94 (CH2Cl2/MeOH, 9.5:0.5); mp: 207 °C
1H NMR: (300 MHz, DMSO-d6): d 8.90 (s, 1H, N–H), 7.81 (s, 1H, N–
H), 7.63 (d, 1H, J = 8.1 Hz, Ar-H), 7.43 (d, 2H, J = 7.8 Hz, Ar-H), 7.25
(t, 2H, J = 7.8 Hz, Ar-H), 6.97 (t, 1H, J = 7.7 Hz, Ar-H), 6.93 (d, 1H,
J = 6.5 Hz, Ar-H), 6.72 (s, 1H, Ar-H), 2.21 (s, 3H, CH3), 2.18 (s, 3H,
CH3); EI MS: m/z (rel. abund. %), 240 (M+, 77), 147 (18), 121
(100), 106 (27.6), 93 (88.3).
C-H3); EI MS: m/z (rel. abund. %), 274 (M+, 100), 276 (M2+
,
31.8), 147 (13.9), 129 (33.8), 127 (69), 129 (24.6), 121 (72), 106
(21.4).
3.3.9. N-(3-Chlorophenyl)-N0-(3,5-dimethylphenyl)-urea (9)
Yield: 0.15 g, 26%; Rf = 0.78 (CH2Cl2/MeOH, 9.5:0.5); mp:
204 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.84 (s, 1H, N–H), 8.58
(s, 1H, N–H), 7.71 (s, 1H, Ar-H), 7.25 (m, 2H, Ar-H), 7.00 (m, 3H,
Ar-H), 6.62 (s, 1H, Ar-H), 2.22 (s, 6H, CH3); EI MS: m/z (rel. abund.
%), 274 (M+, 65.8), 276 (M2+, 21.9), 153 (36.8), 155 (12.5), 147
(34.5), 129 (34.3), 127 (100), 121 (78.9), 106 (21.6).
3.3.17. N-(2,6-Dimethylphenyl)-N0-phenyl-urea (17)
Yield: 0.25 g, 57%; Rf = 0.8 (CH2Cl2/MeOH, 9.5:0.5); mp:
220 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.69 (s, 1H, N–H), 7.68
(s, 1H, N–H), 7.42 (d, 2H, J = 7.7 Hz, Ar-H), 7.23 (t, 2H, J = 7.8 Hz,
Ar-H), 7.05 (d, 2H, J = 7.6 Hz, Ar-H), 6.90 (t, 1H, Ar-H J = 7.3 Hz),
6.87 (t, 1H, J = 7.0 Hz, Ar-H), 2.19 (s, 3H, CH3); EI MS: m/z (rel.
abund. %), 240 (M+, 93.80), 147 (42), 121 (90.2), 106 (65.3), 93
(100).
3.3.10. N-(3-Chlorophenyl)-N0-(2,5-dimethylphenyl)-urea (10)
Yield: 0.55 g, 96%; Rf = 0.75 (CH2Cl2/MeOH, 9.5:0.5); mp:
216 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.22 (s, 1H, N–H), 7.94

K. M. Khan et al. / Bioorg. Med. Chem. 17 (2009) 2447–2451
2451
3.3.18. N-(3,5-Dimethylphenyl)-N0-phenyl-urea (18)
Yield: 0.36 g, 83%; Rf = 0.76 (CH2Cl2/MeOH, 9.5:0.5); mp:
165 °C; 1H NMR: (400 MHz, CD3OD): d 8.57 (s, 1H, N–H), 8.45 (s,
1H, N–H), 7.42 (d, 2H, J = 5.8 Hz, Ar-H), 7.25 (t, 2H, J = 6.0 Hz, Ar-
H), 7.05 (s, 6H, CH3), 6.94 (t, 1H, J = 5.5 Hz, Ar-H), 6.59 (s,
3H,CH3); EI MS: m/z (rel. abund. %), 240 (M+, 100), 147 (20), 121
(83.7), 106 (25.3), 93 (85).
7.15 (d, 1H, J = 7.3 Hz, Ar-H), 7.05 (t, 1H, J = 7.3 Hz, Ar-H), 7.01 (t,
1H, J = 7.06 Hz, Ar-H); EI MS: m/z (rel. abund. %), 292 (M2+, 10.7),
290 (M+, 10), 199 (58.8), 197 (58.6), 173 (86), 171 (100), 93 (87.4).
3.3.26. N-(3-Bromophenyl)-N0-phenyl-urea (26)
Yield: 0.18 g, 33%; Rf = 0.65 (CH2Cl2/MeOH, 9.5:0.5); mp:
173 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.82 (s, 1H, N–H), 8.70
(s, 1H, N–H), 7.83 (d, 2H, J = 7.6 Hz, Ar-H), 7.43 (d, 1H, J = 7.9 Hz,
Ar-H), 7.27 (t, 2H, J = 7.5 Hz, Ar-H), 7.04 (t, 1H, J = 7.1 Hz, Ar-H),
7.02 (s, 1H, Ar-H), 7.00 (t, 1H, J = 7.1 Hz, Ar-H); EI MS: m/z (rel.
abund. %), 292 (M2+, 29.7), 290 (M+, 30.5), 199 (49.7), 197 (51.5),
119 (66.2), 173 (94.7), 171 (100), 93 (87.4).
3.3.19. N-(2,3-Dimethylphenyl)-N0-phenyl-urea (19)
Yield: 0.22 g, 50%; Rf = 0.70 (CH2Cl2/MeOH, 9.5:0.5); mp:
217 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.96 (s, 1H, N–H), 7.81
(s, 1H, N–H), 7.66 (s, 1H, Ar-H), 7.44 (d, 2H, J = 7.6 Hz, Ar-H), 7.25
(t, 2H, J = 7.8 Hz, Ar-H), 7.02 (d, 1H, J = 7.6 Hz, Ar-H), 6.93 (d, 1H,
J = 7.3 Hz, Ar-H), 6.74 (d, 1H, J = 7.5 Hz, Ar-H), 2.23 (s, 3H, CH3),
2.17 (s, 3H, CH3); EI MS: m/z (rel. abund. %), 240 (M+, 24.6), 147
(4.32), 121 (73.68), 106 (55.06), 93 (100).
3.3.27. N-(3-Nitrophenyl)-N0-phenyl-urea (27)
Yield: 0.10 g, 22%; Rf = 0.85 (CH2Cl2/MeOH, 9.5:0.5); mp:
190 °C; 1H NMR: (400 MHz, DMSO-d6): d 9.17 (s, 1H, N–H), 9.79
(s, 1H, N–H), 8.53 (s, 1H, Ar-H), 7.80 (d, 1H, J = 6.34 Hz, Ar-H),
7.69 (d, 1H, J = 7.0 Hz, Ar-H), 7.46 (d, 1H, J = 7.8 Hz, Ar-H), 7.55 (t,
2H, J = 8.14 Hz, Ar-H), 7.29 (t, 2H, J = 7.66 Hz, Ar-H), 6.99 (t, 1H,
J = 7.3 Hz, Ar-H); EI MS: m/z (rel. abund. %), 257 (M+, 25.4), 164
(59.9), 138 (89.7), 119 (100), 93 (81.5).
3.3.20. N-(3-Methoxyphenyl)-N0-phenyl-urea (20)
Yield: 0.38 g, 85%; Rf = 0.62 (CH2Cl2/MeOH, 9.5:0.5); mp:
152 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.62 (s, 1H, N–H), 8.59
(s, 1H, N–H), 7.42 (d, 2H, Ar-H), 7.26 (t, 2H, J = 7.8 Hz, Ar-H), 7.16
(t, 1H, J = 2.9 Hz, Ar-H), 7.13 (s, 1H, Ar-H), 6.95 (t, 1H, J = 7.3 Hz,
Ar-H), 6.90 (d, 1H, J = 2.7 Hz, Ar-H), 6.53 (d, 1H, J = 4.5 Hz, Ar-H),
3.72 (s, 3H, OCH3); EIMS: m/z (rel. abund. %), 242 (M+, 100), 149
(30), 123 (76.7), 119 (22.7), 93 (82.9).
3.3.28. N-(2-Methoxy-5-nitrophenyl)-N0-phenyl-urea (28)
Yield: 0.28 g, 53%; Rf = 0.58 (CH2Cl2/MeOH, 9.5:0.5); mp:
218 °C; 1H NMR: (400 MHz, DMSO-d6): d 9.41 (s, 1H, N–H), 9.10
(s, 1H, N–H), 8.58 (s, 1H, Ar-H), 7.90 (d, 2H, J = 7.8 Hz, Ar-H), 7.46
(d, 1H, J = 7.8 Hz, Ar-H), 7.29 (t, 2H, J = 7.6 Hz, Ar-H), 7.23 (d, 1H,
J = 9.06 Hz, Ar-H), 6.99 (t, 1H, J = 7.3 Hz, Ar-H), 4.03 (s, 3H, OCH3);
EI MS: m/z (rel. abund. %), 287 (M+, 21), 194 (24.6), 168 (100),
153 (21.1), 119 (68), 93 (42.4).
3.3.21. N-(4-Methoxyphenyl)-N0-phenyl-urea (21)
Yield: 0.14 g, 32%; Rf = 0.78 (CH2Cl2/MeOH, 9.5:0.5); mp:
195 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.54 (s, 1H, N–H), 8.43
(s, 1H, N–H), 7.41 (d, 2H, J = 10.2 Hz, Ar-H), 7.33 (d, 2H,
J = 11.3 Hz, Ar-H), 7.25 (t, 2H, J = 10.4 Hz, Ar-H), 6.94 (t, 1H,
J = 9.7 Hz, Ar-H), 6.84 (d, 1H, J = 12.0 Hz, Ar-H), 3.72 (s, 3H,
OCH3); EI MS: m/z (rel. abund. %), 242 (M+, 59.10), 149 (24.23),
123 (88.6), 119 (11.55), 93 (87.08).
Acknowledgement
This work was supported by the Higher Education Commission
(HEC) Pakistan, under the National Research Program for
Universities.
3.3.22. N-(4-Bromophenyl)-N0-phenyl-urea (22)
Yield: 0.34 g, 63%; Rf = 0.72 (CH2Cl2/MeOH, 9.5:0.5); mp:
226 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.78 (s, 1H, N–H), 8.67
(s, 1H, N–H), 7.41 (d, 2H, J = 9.0 Hz, Ar-H), 7.26 (t, 2H, J = 10.0 Hz,
Ar-H), 7.24 (d, 2H, J = 7.3 Hz, Ar-H), 7.01 (d, 2H, J = 7.1 Hz, Ar-H),
6.96 (t, 1H, J = 7.3 Hz, Ar-H); EI MS: m/z (rel. abund. %), 291 (M+,
13.29), 290 (12.35), 172 (6.52), 171 (76.40), 119 (5.63), 93 (100).
References and notes
1. Fournier, J.; Bruneau, C.; Dixneuf, H.; Lécolier, S. J. Org. Chem. 1991, 56, 4456.
2. Groszek, G. Org. Process Res. Dev. 2002, 6, 759.
3. Emerson, J. C.; Steimel, L. H. U.S. Patent, App. 11/333155, 2007 (Assignee:
JohnsonDiversey, Inc., USA).
4. Floersheimer, A.; Furet, P.; Manley, P. W.; Bold, G.; Boss, E.; Guagnano, V.;
Vaupel, A. European Patent, App. EP20030755147, 2005 (Assignee: Novartis
Pharma).
5. Thavonekham, B. Synthesis 1997, 1189.
6. Igarashi, S.; Futagawa, M.; Tanaka, N.; Kawamura, Y.; Morimoto, K. Japanese
Patent, App. PCT/JP1998/000855, 1998.
7. Floersheimer, A.; Furet, P. U.S. Patent, App. 10/515113, 2006.
8. Bigi, F.; Maggi, R.; Sartori, G. Green Chem. 2000, 2, 140.
9. Majer, P.; Randad, R. S. J. Org. Chem. 1994, 59, 1937.
10. Knolker, H.-J.; Braxmeier, T.; Schlechtingen, G. Synlett 1996, 502.
11. Brownlee, M. Diabetes 1994, 43, 836.
3.3.23. N-(3,4-Dimethylphenyl)-N0-phenyl-urea (23)
Yield: 0.18 g, 41%; Rf = 0.82 (CH2Cl2/MeOH, 9.5:0.5); mp:
187 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.54 (s, 1H, N–H), 8.43
(s, 1H, N–H), 7.41 (d, 2H, J = 7.7 Hz, Ar-H), 7.26 (t, 2H, J = 7.5 Hz,
Ar-H), 7.21 (s, 1H, Ar-H), 7.15 (d, 1H, J = 8.0 Hz, Ar-H), 7.0 (d, 1H,
J = 8.1 Hz, Ar-H), 6.93 (t, 1H, J = 7.3 Hz, Ar-H), 2.17 (s, 3H, CH3),
2.14 (s, 3H, CH3); EI MS: m/z (rel. abund. %), 240 (M+, 38.93), 147
(5.63), 121 (88.68), 106 (35.43), 93 (100).
12. Peppa, M.; Uribarri, J.; Vlassara, H. Clin. Diabetes 2003, 21, 186.
13. Monnier, V. M. Arch. Biochem. Biophys. 2003, 419, 1.
14. Vasan, S.; Foiles, P.; Founds, H. Arch. Biochem. Biophys. 2003, 419, 89.
15. (a) Hunt, J. V.; Bottoms, M. A.; Mitchinson, M. J. Biochem. J. 1993, 291, 529; (b)
Ahmed, N. Diabetes Res. Clin. Pract. 2005, 67, 3.
16. Ahmed, M. S.; Ahmed, N. Am. Soc. Nutrit. 2006, 136, 796S.
17. (a) Gugliucci, A. J. Am. Osteopath. Assoc. 2000, 100, 621; (b) Singh, R.; Barden, A.;
Mori, T.; Beilin, L. Diabetologia 2001, 44, 129.
18. (a) Degenhardt, T. P.; Anderson, N. L.; Arrington, D. D.; Beattie, R. J.; Basgen, J.
M. Kidney Int. 2002, 61, 939; (b) Forbes, J. M.; Soulis, T.; Thallas, V.;
Panagiotopoulos, S.; Long, D. M. Diabetologia 2001, 44, 108; (c) Lehman, T.
D.; Ortwerth, B. J. Biochim. Biophys. Acta 2001, 1535, 110; (d) Price, D. L.; Rhett,
P. M.; Thorpe, S. R.; Baynes, J. W. J. Biol. Chem. 2001, 276, 48967.
19. Gugliucci, A.; Menini, T. Life Sci. 2003, 72, 2603.
3.3.24. N-(3,4-Dichlorophenyl)-N0-phenyl-urea (24)
Yield: 0.16 g, 32%; Rf = 0.74 (CH2Cl2/MeOH, 9.5:0.5); mp:
200 °C; 1H NMR: (300 MHz, DMSO-d6): d 8.95 (s, 1H, N–H), 8.76
(s, 1H, N–H), 7.86 (d, 2H, J = 7.54 Hz, Ar-H), 7.50 (d, 1H, J = 8.8 Hz,
Ar-H), 7.43 (d, 1H, J = 7.6 Hz, Ar-H), 7.30 (m, 1H, Ar-H), 6.98 (t,
1H, J = 7.3 Hz, Ar-H), 7.27 (s, 1H, Ar-H); EI MS: m/z (rel. abund.
%), 284 (M2+, 4.5), 282 (M+, 26.2), 280 (39.8), 244 (1.4), 187
(65.4), 163 (100), 161 (100), 93 (91.5).
3.3.25. N-(2-Bromophenyl)-N0-phenyl-urea (25)
20. (a) Hai, S. M. A.; Perveen, S.; Khan, R. A.; Khan, K. M.; Afza, N. Nat. Prod. Res.
2003, 17, 351; (b) Perveen, S.; Hai, S. M. A.; Khan, R. A.; Khan, K. M.; Afza, N.;
Sarfaraz, T. B. Synth. Commun. 2005, 35, 1663.
21. Nakagawa, T.; Yokozawa, T.; Terasawa, K.; Shu, S.; Juneja, L. R. J. Agric. Food
Chem. 2002, 50, 2418.
Yield: 0.35 g, 66%; Rf = 0.86 (CH2Cl2/MeOH, 9.5:0.5); mp:
180 °C; 1H NMR: (300 MHz, DMSO-d6): d 9.42 (s, 1H, N–H), 8.10
(s, 1H, N–H), 8.05 (d, 2H, J = 8.3 Hz, Ar-H), 7.53 (d, 1H, J = 7.1 Hz,
Ar-H), 7.27 (t, 2H, J = 8.8 Hz, Ar-H), 7.21 (t, 1H, J = 10.1 Hz, Ar-H),