Synthesis and spectral analysis of novel 3-(4,6-diarylpyrimidin-2-yl)-2- phenylthiazolidin-4-ones

Article abstract of DOI:10.1007/s10593-010-0462-9

Novel 3-(4,6-diarylpyrimidin-2-yl)-2-phenylthiazolidin-4-ones are synthesized by the multicomponent cyclocondensation reaction of the appropriate 2-amino-4,6-diarylpyrimidines, benzaldehyde, and thioglycolic acid catalyzed by dicyclohexylcarbodiimide. The

Full text of DOI:10.1007/s10593-010-0462-9

Chemistry of Heterocyclic Compounds, Vol. 45, No. 12, 2009
SYNTHESIS AND SPECTRAL ANALYSIS
OF NOVEL 3-(4,6-DIARYLPYRIMIDIN-
2-YL)-2-PHENYLTHIAZOLIDIN-4-ONES
M. Gopalakrishnan1*, J. Thanusu1, V. Kanagarajan1
Novel 3-(4,6-diarylpyrimidin-2-yl)-2-phenylthiazolidin-4-ones are synthesized by the multicomponent
cyclocondensation reaction of the appropriate 2-amino-4,6-diarylpyrimidines, benzaldehyde, and
thioglycolic acid catalyzed by dicyclohexylcarbodiimide. The synthesized compounds have been
characterized by melting point, elemental analysis, MS, FT-IR, 1H and 13C NMR spectroscopic data.
Keywords: 2-amino-4,6-diarylpyrimidines, dicyclohexylcarbodiimide, 3-(4,6-diarylpyrimidin-2-yl)-
2-phenylthiazolidin-4-ones, thioglycolic acid, multicomponent cyclocondensation reaction.
In recent years, multicomponent reactions (MCRs) have received considerable attention and emerged as
one of the most important protocols in organic synthesis and medicinal chemistry. Various 4-thiazolidinones
have attracted substantial attention as they are endowed with a wide range of pharmacological activities.
Peptidoglycan is an essential component of the cell wall of both Gram-positive and Gram-negative bacteria.
4-Thiazolidinones have been reported as novel inhibitors of the bacterial enzyme MurB, which is a precursor,
acting during the biosynthesis of peptidoglycan [1]. A wide variety of biological properties such as
hypolipidemic [2], antidegenerative [3], muscarinic receptor 1 agonist [4], antiproteolytic [5], anti-inflammatory
[6], antiviral [7], antifungal [8], antibacterial [9], antitubercular [10], anticonvulsant [11], respiratory [12], and
hypnotic [13] activities have been reported for 4-thiazolidinones.
Pyrimidines are the basic heterocycles in nucleic acids and have been associated with a number of
biological activities. Substituted aminopyrimidine moiety is common in marketed drugs such as
antiatherosclerotic aronixil, antihistaminic thonzylamine, anxiolytic buspirone, antipsoriatic enazadrem, and
other medicinally relevant compounds. Some notable biological activity of pyrimidine derivatives includes
adenosine receptor antagonists [14], kinase inhibitors [15], analgesic [16], anti-inflammatory [16], inhibitors of
cyclin-dependent kinases 1 and 2 [17], calcium channel antagonist [18], antihistaminic [19], and antitubercular [20]
activities.
Recently, we synthesized 6-aryl-1,2,4,5-tetrazinane-3-thiones [21] by the multicomponent cycloconden-
sation reaction of appropriate aromatic aldehydes, thiourea, and ammonium acetate. Some biolabile fused
indazoles [22], 2,6-diarylpiperidin-4-one derivatives [23-25] for incorporating various other bioactive
_______
* To whom correspondence should be addressed, e-mail: profmgk@yahoo.co.in.
1Synthetic Organic Chemistry Laboratory, Department of Chemistry, Annamalai University, Annamalainagar-
608002, Tamil Nadu, India.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, 1906-1912, December, 2009.
Original article received July 29, 2008; revised version received November 11, 2009.
0009-3122/09/4512-1539©2009 Springer Science+Business Media, Inc.
1539

Scheme 1
NH2
NH
· HNO3
X
HC
CH
Y
N
N
H2N
NH2
Z
Z
NaOH, reflux,
8 h
O
Y
X
12–22
1–11
1S
5
4
2
3
O
O
H
N
HS
,
OH
O
2'
5'
3' N
N 1'
6'
4'
Z
H C –
– C H
N
C
N
11
6
6
11
0oC, stirring, 5 h
Y
X
23–33
23, 24 X = Y = H, 23 Z = H, 24 Z = Cl; 25 X = Z = H, Y = Cl; 26−28 X = Y = H,
26 Z = OMe, 27 Z = Me, 28 Z = F; 29, 30 Y = Z = H, 29 X = Cl, 30 X = OMe;
31-33 X = Cl, Y = H, 31 Z = Me, 32 Z = Cl, 33 Z = F
Scheme 2
X
Y
Z
O
H11C6
N
N
C6H11
C
HS
OH
N
N
+
–
H2O
HN
O
12–22
C
HS
..
O
H
H11C6
N
N
C6H11
C
X
Y
O
Z
H11C6
C6H11
N
H
N
H
N
N
+
O
HN
OH
23–33
S
1540

TABLE 1. Physical and analytical data of 3-(4,6-diarylpyrimidin-2-yl)-
2-phenylthiazolidin-4-ones 23-33
Found, %
——————
Calculated, %
Com-
pound
Empirical
formula
m/z
[M+1]+
mp,°C
Yield, %
.
C
H
N
23
24
25
26
27
28
29
30
31
32
33
C25H19N3OS
73.31
73.35
67.65
67.66
67.62
67.66
71.03
71.08
73.72
73.76
70.23
70.27
67.64
67.66
71.02
71.08
4.60
4.64
4.04
4.06
4.01
4.06
4.72
4.78
4.92
4.96
4.18
4.21
4.01
4.05
4.72
4.78
10.23
10.26
9.41
9.46
9.44
9.46
9.51
9.56
9.89
9.92
9.79
9.83
9.41
9.46
9.55
9.56
145
162
130
110
162
104
114
137
125
130
103
410
444
444
440
424
428
444
440
458
479
462
65
52
49
60
65
70
65
58
55
60
65
C25H18Cl N3OS
C25H18Cl N3OS
C26H21N3O2S
C26H21N3OS
C25H18FN3OS
C25H18Cl N3OS
C26H21N3O2S
C26H20ClN3OS
C25H17Cl2N3OS
C25H17ClFN3OS
68.17
68.21
62.71
62.78
64.98
65.02
4.32
4.36
3.52
3.55
3.65
3.68
9.15
9.17
8.76
8.78
9.04
9.09
heterocyclic nucleus such as 1,2,3-selenadiazoles and 1,2,3-thiadiazoles, and diazepams intact for evaluation of
associated antibacterial and antifungal activities were also prepared in our laboratory. In the interest of the
above, we planned to synthesize a system that comprises both 4-thiazolidinones and 2-amino-4,6-diaryl-
pyrimidine components together to give a heterocyclic structure like the title 3-(4,6-diarylpyrimidin-2-yl)-
2-phenylthiazolidin-4-ones.
Initially, a conversion of 2-amino-4,6-diarylpyrimidines 12-22 to 3-(4,6-diarylpyrimidin-2-yl)-2-phenyl-
thiazolidin-4-ones 23-33 was tried in the absence of dicyclohexylcarbodiimide (DCC). No yields were achieved.
Instead, if DCC was used as a dehydrating agent, the yield of the product was improved significantly (i.e., about
65%) in the stirring mode at about 0ºC. The Claisen−Schmidt condensation of equimolar quantities of various p-
substituted acetophenones with different m- and p-substituted benzaldehydes in the presence of sodium hydroxide
as a catalyst yields 1,3-diarylprop-2-en-1-ones 1-11. When compounds 1-11 are treated with guanidine nitrate in
the presence of NaOH in refluxing ethanol for 8 h they give 2-amino-4,6-diarylpyrimidines 12-22. The novel
title compounds 3-(4,6-diarylpyrimidin-2-yl)-2-phenylthiazolidin-4-ones 23-33 are synthe-sized by the reaction
of benzaldehyde and thioglycolic acid with 2-amino-4,6-diphenylpyrimidine in dry dichloromethane at 0°C
catalyzed by DCC. The analytical data of compounds 23-33 are given in Table 1. The importance of the title
compounds is due to their diverse potential, broad-spectrum biological activity. The structure of the newly
1
13
synthesized compounds 23-33 is confirmed by elemental analysis, MS, FT-IR, H and C NMR spectroscopic
data. A possible reaction mechanism (Scheme 2) has been proposed for the conversion of 2-amino-4,6-
diarylpyrimidines to 3-(4,6-diarylpyrimidin-2-yl)-2-phenylthiazolidin-4-ones catalyzed by DCC.
EXPERIMENTAL
All the reported melting points were taken in open capillaries and were uncorrected. IR spectra were
recorded in KBr (pellet forms) on a Nicolet-Avatar–330 FT-IR spectrophotometer and noteworthy absorption
1541

1
13
values (cm–1) alone are listed. H and C NMR spectra were recorded at 400 and 100 MHz, respectively, on a
Bruker AMX 400 NMR spectrometer using DMSO-d6 as a solvent. The ESI + ve MS spectra were recorded on a
Bruker Daltonics LC-MS spectrometer. Satisfactory microanalysis was obtained on a Carlo Erba 1106 CHN
analyzer.
By adopting the literature precedent, 1,3-diarylprop-2-en-1-ones 1–11 [26] and 2-amino-4,6-diaryl-
pyrimidines 12–22 [27] were synthesized.
2-Phenyl-3-(4',6'-Diphenylpyrimidin-2'-yl)thiazolidin-4-one (23) (General Method). To an ice-cold
stirred solution of 2-amino-4,6-diphenylpyrimidine (2.47 g, 0.01 mol) in dry dichloromethane benzaldehyde
(1.06 g, 0.01 mol) was added in drops followed by DCC (2.06 g, 0.0l mol). After 5 min, thioglycolic acid
(0.92 g, 0.01 mol) was added and stirring was continued at 0°C for an additional 5 h. Then the reaction mixture
was filtered off to remove dicyclohexylurea followed by washing with 5% citric acid, 10% sodium bicarbonate,
brine solution, and finally with water, and dried over anhydrous sodium sulfate. After evaporation of the solvent
under reduced pressure, a gummy mass was obtained, which solidified on treatment with petroleum ether
(bp 40–60°C). Final purification of compound 23 was done by column chromatography using silica gel
(100-200 mesh), with ethyl acetate–petroleum ether (bp 40-60°C) in the ratio of 2:8 as an eluent. IR spectrum, ν,
cm–1: 3125, 3033, 2927, 2851, 1716, 1627, 1576, 1350, 710, 698, 649. 1H NMR spectrum, δ, ppm (J, Hz): 3.21
(1H, d, J = 15.4, H-5a); 3.38 (1H, d, J = 15.4, H-5e); 5.25 (1H, s, H-2); 7.19–8.37 (16H, m, arom.). A singlet for
CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons. 13C NMR spectrum, δ, ppm:
34.0 (C-5), 62.5 (C-2), 108.1 (C-5'), 131.4 (C-2'''), 125.9–128.8 (C arom.), 139.1 (C-4"), 139.1 (C-6"), 161.3 (C-4'),
161.3 (C-6'), 163.8 (C-2'), 170.6 (C-4).
Compounds 24-33 were synthesized in a similar way.
3-[6'-(3"-Chlorophenyl)-4'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (24). IR spectrum, ν,
cm–1: 3120, 3033, 2927, 2851, 1696, 1627, 1575, 1310, 894, 710, 650, 647. 1H NMR spectrum, δ, ppm (J, Hz):
3.22 (1H, d, J = 15.4, H-5a); 3.39 (1H, d, J = 15.3, H-5e); 5.27 (1H, s, H-2); 7.31–8.44 (15H, m, arom.).
A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons. 13C NMR
spectrum, δ, ppm: 33.9 (C-5), 62.6 (C-2), 108.8 (C-5'), 127.5–133.1 (C arom.), 131.4 (C-2'"), 135.9 (C-ipso), 139.1
(C-4"), 139.7 (C-6"), 164.9 (C-4'), 165.0 (C-6'), 162.9 (C-2'), 170.6 (C-4).
3-[6'-(4"-Chlorophenyl)-4'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (25). IR spectrum,
ν, cm–1: 3115, 3033, 2927, 2850, 1714, 1627, 1575, 1344, 894, 767, 690, 648. 1H NMR spectrum, δ, ppm (J, Hz):
3.22 (1H, d, J = 15.4, H-5a); 3.39 (1H, d, J = 15.4, H-5e); 5.27 (1H, s, H-2); 7.21–8.24 (15H, m, arom.). A singlet
13
for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons. C NMR spectrum,
δ, ppm: 33.9 (C-5), 62.4 (C-2), 108.9 (C-5'), 124.6–129.0 (C arom.), 130.6 (C-ipso), 131.5 (C-2"'), 139.0 (C-4"),
141.8 (C-6"), 164.9 (C-4'), 165.5 (C-6'), 162.7 (C-2'), 170.6 (C-4).
3-[6'-(3"-Methoxyphenyl)-4'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (26). IR spectrum,
1
ν, cm–1: 3065, 3038, 2927, 2851, 1714, 1627, 1577, 1351, 700, 650, 649. H NMR spectrum, δ, ppm (J, Hz):
3.23 (1H, d, J = 15.35, H-5a); 3.39 (1H, d, J = 15.3, H-5e); 3.84 (3H, s, OCH3); 5.28 (1H, s, H-2); 7.21-8.21
(15H, m, arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic
protons. 13C NMR spectrum, δ, ppm: 34.5 (C-5), 54.9 (OCH3 on aryl ring), 62.5 (C-2), 108.7 (C-5'), 126.0-128.6
(C arom.), 129.1 (C-2"'), 139.1 (C-4"), 141.5 (C-6"), 164.0 (C-4'), 165.0 (C-6'), 162.3 (C-2'), 170.6 (C-4).
3-[6'-(3"-Methylphenyl)-4'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (27). IR spectrum, ν,
cm–1: 3060, 3033, 2926, 2852, 1715, 1627, 1579, 1350, 714, 700, 643. 1H NMR spectrum, δ, ppm (J, Hz): 2.32
(3H, s, CH3), 3.23 (1H, d, J = 15.3, H-5a); 3.40 (1H, d, J = 15.4, H-5e); 5.27 (1H, s, H-2); 7.20–8.24 (15H, m,
arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons.
13C NMR spectrum, δ, ppm: 24.5 CH3 on aryl ring, 34.1 (C-5), 62.6 (C-2), 108.4 (C-5'), 126.0–131.4 (C arom.),
133.1 (C-2"'), 135.9 (C-ipso), 138.7 (C-4"), 139.1 (C-6"), 164.9 (C-4'), 165.5 (C-6'), 162.6 (C-2), 170.8 (C-4).
3-[6'-(3"-Fluorophenyl)-4'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (28). IR spectrum, ν,
cm–1: 3071, 3027, 2928, 2852, 1712, 1626, 1575, 1352, 836, 769, 698. 1H NMR spectrum, δ, ppm (J, Hz): 3.20
1542

(1H, d, J = 15.2, H-5a); 3.37 (1H, d, J = 15.3, H-5e); 5.26 (1H, s, H-2); 6.64–8.19 (15H, m, arom.). A singlet for CH
proton at position 5' of the pyrimidine moiety is merged with aromatic protons. 13C NMR spectrum, δ, ppm: 34.5
(C-5), 62.9 (C-2), 108.9 (C-5'), 127.3–143.1 (C arom.), 143.6 (C-2"'), 145.1 (C-4"), 146.1 (C-6"), 166.8 (C-4'),
167.0 (C-6'), 163.9 (C-2'), 171.4 (C-4).
3-[4'-(4"-Chlorophenyl)-6'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (29). IR spectrum, ν,
cm–1: 3071, 3027, 2926, 2852, 1721, 1627, 1576, 1398, 782, 730, 693, 582. 1H NMR spectrum, δ, ppm (J, Hz):
3.21 (1H, d, J = 15.3, H-5a); 3.38 (1H, d, J = 15.3, H-5e); 5.25 (1H, s, H-2); 7.15–7.93 (15H, m, arom.). A
singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons. 13C NMR
spectrum, δ, ppm: 34.1 (C-5), 62.9 (C-2), 108.9 (C-5'), 126.5–128.9 (C arom.); 129.2 (C-2"'), 139.1 (C-4"), 141.9
(C-6"), 164.4 (C-4'), 165.3 (C-6'), 162.5 (C-2'), 170.8 (C-4).
3-[4'-(4"-Methoxyphenyl)-6'-phenylpyrimidin-2'-yl]-2-phenylthiazolidin-4-one (30). IR spectrum, ν,
cm-1: 3065, 3033, 2928, 2851, 1715, 1627, 1590, 1370, 835, 770, 699, 656. 1H NMR spectrum, δ, ppm (J, Hz): 3.20
(1H, d, J = 15.1, H-5a); 3.37 (1H, d, J = 15.3, H-5e); 3.86 (3H, s, OCH3); 5.26 (1H, s, H-2); 6.97-8.20 (15H, m,
arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons. 13C NMR
spectrum, δ, ppm: 34.1 (C-5), 55.2 (OCH3 on aryl ring), 62.5 (C-2), 108.6 (C-5'), 114.1-129.1 (C arom.), 129.5 (C-
2"'), 130.2 (C-ipso), 139.2 (C-6"), 146.1 (C-4"), 163.8 (C-4'), 164.4 (C-6'); 161.2 (C-2'), 170.7 (C-4).
3-[4'-(4''-Chlorophenyl)-6'-(3''-methylphenyl)pyrimidin-2'-yl]-2-phenylthiazolidin-4-one (31). IR
spectrum, ν, cm–1: 3060, 3027, 2927, 2851, 1721, 1626, 1576, 1398, 781, 728, 694, 650. 1H NMR spectrum, δ,
ppm (J, Hz): 2.40 (3H, s, CH3); 3.20 (1H, d, J = 15.0, H-5a); 3.37 (1H, d, J = 15.1, H-5e); 5.26 (1H, s, H-2);
7.18–8.33 (14H, m, arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with
aromatic protons. 13C NMR spectrum, δ, ppm: 25.2 (CH3 on aryl ring), 34.5 (C-5), 62.9 (C-2), 108.9 (C-5'),
131.4 (C-2"'), 126.1–130.4 (C arom.), 133.1 (C-ipso), 138.7 (C-6"), 139.1 (C-4"), 164.8 (C-4'), 165.0 (C-6'),
161.2 (C-2'), 170.8 (C-4).
3-[4'-(4''-Chlorophenyl)-6'-(3''-chlorophenyl)pyrimidin-2'-yl]-2-phenylthiazolidin-4-one (32). IR
spectrum, ν, cm–1: 3060, 3027, 2927, 2852, 1727, 1627, 1575, 1400, 897, 787, 730, 693. 1H NMR spectrum, δ,
ppm (J, Hz): 3.20 (1H, d, J = 15.2, H-5a); 3.36 (1H, d, J = 15.2, H-5e); 5.26 (1H, s, H-2); 7.28–8.20 (14H, m,
arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons.
13C NMR spectrum, δ, ppm: 34.5 (C-5), 62.5 (C-2), 108.7 (C-5'), 129.1 (C-2"'), 126.0–128.6 (C arom.), 139.1
(C-6"). 141.8 (C-4"), 164.1 (C-4'), 161.3 (C-6'), 165.3 (C-2'), 170.9 (C-4).
3-[4'-(4''-Chlorophenyl)-6'-(3''-fluorophenyl)pyrimidin-2'-yl]-2-phenylthiazolidin-4-one (33). IR
spectrum, ν, cm–1: 3065, 3027, 2926, 2853, 1719, 1627, 1576, 1394, 897, 833, 776, 728, 695. 1H NMR spectrum,
δ, ppm (J, Hz): 3.18 (1H, d, J = 14.9, H-5a); 3.35 (1H, d, J = 14.9, H-5e); 5.26 (1H, s, H-2); 7.18–8.19 (14H, m,
arom.). A singlet for CH proton in position 5' of the pyrimidine moiety is merged with aromatic protons.
13C NMR spectrum, δ, ppm: 34.1 (C-5), 62.6 (C-2), 110.1 (C-5'), 133.2 (C-2"'), 127.3–143.1 (C arom.), 145.1
(C-6"), 146.8 (C-4"), 166.8 (C-4'), 167.0 (C-6'), 163.4 (C-2"), 171.8 (C-4).
The authors are thankful to NMR Research Centre, Indian Institute of Science, Bangalore, for recording
spectra. One of the authors, V. Kanagarajan, is grateful to the Council of Scientific and Industrial Research
(CSIR), New Delhi, Republic of India, for providing financial support in the form of a CSIR-Senior Research
Fellowship in Organic Chemistry. J. Thanusu wishes to thank Annamalai University authorities for providing
financial support in the form of a Research Fellowship.
REFERENCES
1.
C. J. Andres, J. J. Bronson, S. V. D'Andrea, M. S. Deshpande, P. J. Falk, K. A. Grant-Young,
W. E. Harte, Hsu-Tso Ho, P. F. Misco, J. G. Robertson, D. Stock, Yaxiong Sun, and A. W. Walsh,
Bioorg. Med. Chem. Lett., 10, 715 (2000).
1543

2.
3.
4.
G. K. Nampurath, S. P. Mathew, Vivek Khanna, R. T. Zachariah, Suman Kanji, and Mallikarjuna Rao
Chamallamudi, Chem. Biol. Interact., 171, 363 (2008).
R. Ottanà, R. Maccari, R. Ciurleo, M. G. Vigorita, A. M. Panico, V. Cardile, F. Garufi, and
S. Ronsisvalle, Bioorg. Med. Chem., 15, 7618 (2007).
J. N. Narendra Sharath Chandra, Manish Malviya, C. T. Sadashiva, M. N. Subhash, and K. S. Rangappa,
Neurochem. Int., 52, 376 (2008).
5.
6.
V. Kishore, N. K. Narain, S. Kumar, and S. S. Parmar, Pharmacol. Res. Commun., 8, 43 (1976).
B. B. Newbould, Br. J. Pharmacol. Chemother., 24, 632 (1965).
7.
8.
P. Schauer, M. Likar, M. Tisler, A. Krbavcic, and A. Pollak, Pathol. Microbiol., 28, 382 (1965).
V. N. Chaubey and H. Singh, Bull. Chem. Soc. Jpn., 43, 2233 (1970).
9.
E. B. Akerblom, J. Med. Chem., 17, 609 (1974).
10.
11.
12.
13.
14.
M. D. Litvinchuk, Farmakol. Toksikol., 26, 725 (1963).
A. K. Dimri and S. S. Parmar, J. Heterocycl. Chem., 15, 335 (1978).
S. S. Parmar, C. Dwivedi, A. Chaudhari, and T. K. Gupta, J. Med. Chem., 15, 99 (1972).
S. P. Singh, S. S. Parmar, Krishna Raman, and V. I. Stenberg, Chem. Rev., 81, 175 (1981).
P. D. Jacobus, Van Veldhoven, C. W. Lisa, Chang, J. Künzel, T. Mulder-Krieger, R. Struensee-Link,
M. W. Beukers, J. Brussee, and I. P. Ijzerman, Bioorg. Med. Chem., 16, 2741 (2008).
T. V. Hughes, S. L. Emanuel, A. K. Beck, S. K. Wetter, P. J. Connolly, Prabha Karnachi, Michael
Reuman, Jabed Seraj, AR Fuentes-Pesquera, R. H. Gruninger, S. A. Middleton, Ronghui Lin,
J. M. Davis, and D. F. C. Moffat, Bioorg. Med. Chem. Lett., 17, 3266 (2007).
M. T. Chhabria, H. G. Bhatt, H. G. Raval, and P. M. Oza, Bioorg. Med. Chem. Lett., 17, 1022 (2007).
K. L. Sayle, J. F. Bentley, T. Boyle, A. H. Calvert, Yuzhu Cheng, N. J. Curtin, J. A. Endicott,
B. T. Golding, I. R. Hardcastle, P. Jewsbury, V. Mesguiche, D. R. Newell, M. E. M. Noble,
R. J. Parsons, D. J. Pratt, L. Z. Wang, and R. J. Griffin, Bioorg. Med. Chem. Lett., 13, 3079 (2003).
A. Pastor, R. Alajarin, J. J. Vaquero, J. Alvarez-Builla, M. Fau de Casa-Juana, C. Sunkel, J. G. Priego,
I. Fonseca, and J. Sanz-Aparicio, Tetrahedron, 50, 8085 (1994).
15.
16.
17.
18.
19.
20.
M. S. Youssouf, P. Kaiser, G. D. Singh, S. Singh, S. Bani, V. K. Gupta, N. K. Satti, K. A. Suri, and
R. K. Johri, Int. Immunopharmacol., 8, 1049 (2008).
C. Gasse, D. Douguet, V. Huteau, G. Marchal, H. Munier-Lehmann, and S. Poche, Bioorg. Med. Chem.,
16, 6075 (2008).
21.
22.
M. Gopalakrishnan, P. Sureshkumar, V. Kanagarajan, and J. Thanusu, J. Sulf. Chem., 28, 383 (2007).
M. Gopalakrishnan, P. Sureshkumar, J. Thanusu, and V. Kanagarajan, J. Enz. Inhib. Med. Chem., 23,
974 (2008).
23.
M. Gopalakrishnan, P. Sureshkumar, J. Thanusu, and V. Kanagarajan, J. Enz. Inhib. Med. Chem., 23,
347 (2008).
24.
25.
M. Gopalakrishnan, J. Thanusu, and V. Kanagarajan, Med. Chem. Res., 16, 392 (2007).
M. Gopalakrishnan, P. Sureshkumar, J. Thanusu, V. Kanagarajan, R. Govindaraju, and G. Jayasri,
J. Enz. Inhib. Med. Chem., 22, 709 (2007).
26.
27.
W. Guthrie and X. P. Wang, Can. J. Chem., 69, 339 (1991).
S. Kothari, M. Singhal, D. Vijayvergia, R. Vyas, and B. L. Verma. J. Indian Chem. Soc., 77, 329 (2000).
1544