Chemotherapy of?leishmaniasis part III: synthesis and?bioevaluation of?novel aryl substituted terpenyl pyrimidines as?antileishmanial agents

Article abstract of DOI:10.1016/j.ejmech.2006.02.004

Some aryl substituted terpenyl pyrimidines 4 (a-p) have been synthesized using novel synthetic methods. The compounds were screened for in vitro antileishmanial activity against promastigotes. Compounds 4c, 4i and 4l showed IC₅₀ values as 35, 3

Full text of DOI:10.1016/j.ejmech.2006.02.004

European Journal of Medicinal Chemistry 41 (2006) 779–785
http://france.elsevier.com/direct/ejmech
Short Communication
Chemotherapy of leishmaniasis part III:
synthesis and bioevaluation of novel aryl
substituted terpenyl pyrimidines as antileishmanial agents
☆
Naveen Chandra a, Susmita Pandey a, Ramesh b, S.N. Suryawanshi a,*, Suman Gupta b
a Division of Medicinal Chemistry, Central Drug Research Institute, Lucknow 226001, India
b Division of Parasitology, Central Drug Research Institute, Lucknow 226001, India
Received 1 September 2004; received in revised form 31 January 2006; accepted 16 February 2006
Available online 12 May 2006
Abstract
Some aryl substituted terpenyl pyrimidines 4 (a–p) have been synthesized using novel synthetic methods. The compounds were screened for
in vitro antileishmanial activity against promastigotes. Compounds 4c, 4i and 4l showed IC50 values as 35, 35 and 25 μg ml–1.
© 2006 Elsevier SAS. All rights reserved.
Keywords: Ionones; Aryl substituted terpenyl pyrimidines; Antileishmanial activity; In vitro; MTT; L. donovani
1. Introduction
activities. Rationally designed 2,4-diaminopyrimidines [12]
and some computer aided molecules [13] are also giving
further inputs in the leishmanial dihydrofolate reductase activ-
ity. In continuation of our studies on terpenyl pyrimidines as
novel antileishmanial agents [14], we designed some novel ter-
penyl pyrimidines, having added aryl substitution and evalu-
ated for their in vitro antileishmanial activity and the results
are reported in this communication.
Leishmaniasis is an infection caused by protozoa of the
genus Leishmania presenting several forms of the disease such
as cutaneous, mucocutaneous and visceral leishmaniasis, which
can be fatal when untreated. The chemotherapy currently avail-
able for leishmaniasis is far from satisfactory. Resistance to the
pentavalent antimonials [1,2], which have been recommended
drugs for the treatment of both visceral and cutaneous leishma-
niasis for > 50 years, is now widespread in India. Although
new drugs have become available in recent years for the treat-
ment of visceral leishmaniasis including amphotericin B lipid
complex [3] and the oral drug miltefosine [4], treatment pro-
blems remain. Currently, efforts are being made to search for
new molecules from the natural sources and in this endeavor
diaryl heptanoids [5–7], oxygenated abietanes [8], diterpene
quinones [9] are showing promise as new lead molecules. Ran-
domly designed heterocyclic ionone like molecules [10] and
some novel terpenyl 2,4-diamino pyrimidines [11] are showing
promising antimicrobial and dihydrofolate reductase inhibitory
2. Chemistry
The chalcones 3 (a–h) have been synthesized from α-ionone
1 and substituted benzaldehydes 2 as shown in Scheme 1.
Classical literature methods were of little help on a prepara-
tive scale as it resulted in excessive decomposition of α-ionone
1. Powdered sodium hydroxide in aprotic solvents was also of
little help [15]. However, phase transfer catalyzed conditions
used for the phenolic ketones [16] proved useful. The reaction
of α-ionone 1 with 3,4-dimethoxybenzaldehyde under phase
transfer conditions was very facile and furnished chalcone 3a
in 75% yield. Similarly 3,4,5-trimethoxybenzaldehyde under
identical reaction conditions furnished chalcone 3b in quantita-
tive yield. Under identical conditions p-chlorobenzaldehyde
and p-fluoro benzaldehyde furnished 3c and 3d in quantitative
☆
CDRI Communication No 6627.
* Corresponding author.
E-mail address: shivajins@yahoo.co.in (S.N. Suryawanshi).
0223-5234/$ - see front matter © 2006 Elsevier SAS. All rights reserved.
doi:10.1016/j.ejmech.2006.02.004

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N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
Scheme 1.
yield. The reaction of p-benzyloxybenzaldehyde with α-ionone
was equally facile and furnished chalcone 3e in 89% yield as a
pale yellow crystalline solid melting at 81–82 °C. Nitrobenzal-
dehydes were equally reactive and furnished chalcones 3 (f–h)
in respectable yields.
synthesized. Nitro chalcones were equally more facile to react
with guanidine and morpholino guanidine to furnish pyrimi-
dines 4 (k–p) in quantitative yields (Scheme 2).
3. Biological activities
The reaction of guanidine with chalcone 3 (a–h) was not
only facile but it was also regiospecific in manner. The reaction
of chalcone 3a with guanidine in isopropanol in the presence
of silver oxide furnished pyrimidine 4a in 42% yield as a crys-
talline solid melting at 101–102 °C. The structure was assigned
3.1. Material and methods
3.1.1. Parasite
The WHO reference strain of Leishmania donovani
(MHOM/IN/80/Dd8) obtained from Imperial College, London
(UK) in 1979 has been maintained since then in this laboratory
in vitro as promastigotes in Medium 199 (Sigma Chemical Co.,
USA) supplemented with 10% fetal calf serum (GIBCO) and
as amastigotes in golden hamsters.
on the basis of H and 13C NMR spectra. The H NMR spec-
trum of 4a displayed a doublet at 6.30 ppm (j = 16.00 Hz) for
the H-4 proton and doublet of doublets at 6.80 ppm (j = 16.00,
10.00 Hz, 1H) for the H-5 proton and it established the as-
signed structure 4a. Under identical reaction conditions 4 (b–
e) were synthesized in good yields. Morpholino substituted
pyrimidines were also synthesized under identical reaction con-
ditions. The reaction of chalcone 3a with morpholino guani-
dine in the presence of silver oxide in isopropanol (Δ, 16 h)
furnished morpholino pyrimidine 4f in 38% yield as a crystal-
line solid melting at 123–125 °C. The structure was assigned
1
1
3.2. In vitro assay
3.2.1. For extracellular (against promastigotes) leishmanicidal
activity
1
on the basis of H NMR which showed a doublet at 6.35 ppm
The effect of compounds on the viability of Leishmania
promastigotes was assessed by monitoring the MTT [3-(4,5-di-
methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] metabo-
lism [17] (Sigma Chemical Co.) after a 96 h culture period in
(j = 16.00 Hz) for the H-4 proton and doublet of doublets at
6.8 ppm (j = 16.00, 10.00 Hz) for the H-5 proton. Under iden-
tical reaction conditions morpholino guanidine 4 (g–j) were

N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
781
Scheme 2.
the presence of the respective compounds. Parasites in station-
ary culture stage were seeded at 1 × 106/100 μl medium 199
per well in 96-well flat bottom microtitre plates (Cellstar).
Further 100 μl of medium 199 per well with different concen-
trations of test compounds or drug standard, dissolved in
DMSO were added in triplicate to achieve desired concentra-
tions (12.5–200 μg ml–1). Parallel dilutions of DMSO alone did
not affect the parasite growth. The plates were incubated at
25 °C for 92 h prior to MTT (20 μl per well of a 5 mg ml–1
PBS stock) addition and then for further 4–5 hours. MTT pro-
cessing was stopped and formazan crystals solubilized by add-
ing 50 μl per well acidified 20% SDS (Qualigens, India) and
incubating overnight at 37 °C. The relative amount of forma-
zan per well produced by viable cells was measured photome-
trically at 570 nm. Two independent experiments were per-
formed for the determination of sensitivity of each
compound. As a control, the activity of each compound was
determined, and no substantial interaction was found.
Further synthesis of new aryl substituted terpenyl pyrimidines
and in vitro screening against L. donovani promastigotes would
be necessary to find improved drug candidates for in vivo test-
ing.
5. Experimental
The reported melting points (°C) are the uncorrected ones.
The infrared spectra were recorded in KBr on a Perkin Elmer
model 881. NMR spectra were obtained in CDCl3 (with Me4Si
internal standard, Aldrich) and are reported in ppm downfield
from Me4Si. Proton, carbon NMR spectra were recorded on
Bruker Advance DRX 2000 instrument. Electron impact mass
spectra were recorded on a Jeol JMS-D-300 spectrometer with
Table 1
Evaluation of in vitro antileishmanial activity of compounds against
promastigotes by MTT assay
4. Results and discussion
Compounds
Mean IC values (μg ml–1
)
S.E. (N)
IC50
IC90
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
100 2.0
Inactive
35 0.5
60 3.0
50 1.2
Inactive
Inactive
Inactive
35 1.5
Inactive
Inactive
25 1.7
75 2.3
Inactive
Inactive
Inactive
2.5 0.12
250 1.5
Inactive
60 2.0
200 3.5
250 2.5
Inactive
Inactive
Inactive
75 2.0
Inactive
Inactive
50 3.5
250 2.8
Inactive
Inactive
Inactive
5.0 0.35
The leishmanicidal activity of aryl substituted terpenyl pyr-
imidines 4 (a–p) was studied in vitro on L. donovani promas-
tigotes. Substitution on the aryl ring has a profound effect on
the leishmanicidal activity. Most of the compounds having
methoxy substitution on the aromatic ring are either inactive
or have very poor activity. However, compound 4i (Table 1)
having benzyloxy substitution on the aromatic ring showed
IC50 and IC90 values as 35 1.5 and 75 2.0 μg ml–1, respec-
tively. Compounds having electron withdrawing halogen sub-
stitution at p-position on aromatic ring also showed respective
figures of IC50 value as 35 0.5 and IC90 value as 60 2.
0 μg ml–1 in 4c. Comparatively better profile was found in
compound 4l having p-nitro substitution which showed IC50
value as 25 1.7 and IC90 value as 50 3.5 μg ml–1. However,
none of the compound tested found better than pentamidine.
Pentamidine
N: pooled data of two independent experiments.

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N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
the ionization potential of 70 eV. Elemental analyses were car-
ried out on a Carlo-Erba EA 1108 instrument.
132.344 (s), 133.765 (s), 136.629 (s), 141.929 (d), 149.573
(d), 189.040 (s). MS: (m/e) 315 (M+ + 1). Analysis calculated
for C20H23OCl: C, 76.29; H, 7.36. Found: C, 76.17; H, 7.57.
5.1. General procedure for the synthesis
of 1-(3,4-dimethoxyphenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2′-en-
1′-yl)-pent-1,4-diene-3-one (3a)
5.1.3. 1-(4-Fluorophenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2′-en-
1′-yl)-pent-1,4-dien-3-one (3d)
Yield: 77%. M.p. 185–187 °C. IR (KBr, cm−1) 3016, 2959,
1
2921, 2867, 1658, 1598, 1509. H NMR (CDCl3, 200 MHz) δ
A mixture of α-ionone (1.92 g, 2.04 ml, 10 mmol), 3,4-di-
methoxybenzaldehyde (1.83 g, 11 mmol), cetyltrimethyl am-
monium bromide (0.14 g, 1 mmol), sodium hydroxide (1.0 g,
30 mmol) and water (50 ml) was stirred at room temperature
for 24 h. After completion of the reaction (TLC monitoring), it
was extracted with ethylacetate (2 × 50 ml). The combined or-
ganic extract was washed with water (2 × 50 ml), brine solu-
tion (50 ml), dried (Na2SO4), and the solvent was removed in
vacuo. The crude product was purified by column chromato-
graphy (SiO2, 60–120 mesh). Elution with 3% ethylacetate in
hexane furnished dark yellow solid which on crystallization
(ether/hexane) gave 3a, as a pale yellow crystalline solid
(2.55 g, 75%). M.p. 110–111 °C. IR (KBr, cm−1) 2956,
0.89 (s, 3H), 0.94 (s, 3H), 1.28 (m, 2H), 1.45 (m, 1H), 1.59 (s,
3H), 2.05 (m, 2H), 2.40 (d, j = 10.00 Hz, 1H), 5.50 (m, 1H),
6.38 (d, j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H),
7.00 (d, j = 16.00 Hz, 1H), 7.15 (m, 2H), 7.65 (m, 2H), 7.70 (d,
j = 16.00 Hz, 1H). 13C NMR (CDCl3, 200 MHz) δ 23.242 (q),
23.448 (t), 27.237 (q) 28.246 (q), 31.616 (t), 33.055 (s), 54.986
(d), 116.215 (d), 116.505 (d), 123.081 (d), 124.880 (d),
130.480 (d), 130.649 (d), 130.964 (d), 132.499 (s), 142.011
(d), 149.302 (d), 161.835 (s), 166.832 (s), 189.060 (s). MS:
(m/e) 299 (M+ + 1).
5.1.4. 1-(4-Benzyloxyphenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2-
en-1′-yl)-pent-1,4-dien-3-one (3e)
1
1655, 1588, 1509. H NMR (CDCl3, 200 MHz) δ 0.88 (s,
Yield: 89%. M.p. 81–82 °C. IR (KBr, cm−1) 2913, 1664,
3H), 0.94 (s, 3H), 1.20 (m, 2H), 1.60 (s, 3H), 2.00 (m, 2H),
2.30 (d, j = 10.00 Hz, 1H), 3.90 (s, 3H), 5.50 (m, 1H), 6.40 (d,
j = 16.00 Hz, 1H), 6.80 (m, 3H), 7.10 (m, 2H), 7.60 (d,
j = 16.00 Hz, 1H). 13C NMR (CDCl3, 200 MHz) δ 23.283
(q), 23.460 (t), 27.279 (q), 28.238 (q), 31.641 (t), 33.051 (s),
54.960 (d), 2 × 53.352 (q), 110.436 (d), 111.550 (d), 122.966
(d), 123.368 (d), 123.616 (d), 128.250 (s), 130.721 (d),
132.495 (s), 143.509 (d), 148.694 (d), 149.671 (s), 151.716
(s) 189.151 (s). MS: (m/e) 341 (M+ + 1). Analysis calculated
for C22H28O3: C, 74.56, H, 8.16. Found: C, 74.86; H, 8.29.
1
1625, 1583, 1564. H NMR (CDCl3, 200 MHz) δ 0.90 (s,
3H), 0.95 (s, 3H), 1.25 (m, 1H), 1.55 (m, 1H), 1.60 (s, 3H),
2.10 (m, 2H), 2.35 (d, j = 10.00 Hz, 1H), 5.10 (s, 2H), 5.55 (m,
1H), 6.40 (d, j = 15.00 Hz, 1H), 6.80 (dd, j = 15.00, 10.00 Hz,
1H), 7.00 (m, 2H), 7.45 (m, 6H). 13C NMR (CDCl3, 200 MHz)
δ 23.286 (q), 23.480 (t), 27.298 (q), 28.258 (q), 31.681 (t),
33.068 (s), 54.995 (d), 70.530 (t), 2 × 115.696 (d), 122.974
(d), 123.234 (d), 2 × 127.858 (d), 126.255 (s), 128.556 (d),
2 × 129.064 (d), 2 × 130.441 (d), 131.100 (d), 132.543 (s),
136.874 (s), 143.166 (d), 148.658 (d), 161.105 (s), 189.335
(s). MS: (m/e) 387 (M+ + 1). Analysis calculated for
C27H30O2: C, 83.89, H, 7.82. Found: C, 83.29; H, 7.85.
5.1.1. 1-(3,4,5-Trimethoxyphenyl)-5-(2′,6′,6′-trimethyl-
cyclohex-2′-en-1′-yl)-pent-1,4-dien-3-one (3b)
Yield: 72%. M.p. 85–86 °C; IR (KBr, cm−1) 3017, 2962,
1
5.1.5. 1-(4-Nitro-phenyl)-5-(2′, 6′, 6′-trimethyl-cyclohex-2-en-
1′-yl)-pent-1,4-dien-3-one (3f)
1654, 1623, 1586. H NMR (CDCl3, 200 MHz) δ 0.88 (s,
3H), 0.95 (s, 3H), 1.20 (m, 2H), 1.55 (s, 3H), 2.05 (m, 2H),
Yield: 67%. M.p. 125–127 °C. IR (KBr, cm−1) 2959, 2921,
1658, 1598, 1509. 1H NMR (CDCl3, 200 MHz) δ 0.86 (s, 3H),
0.96 (s, 3H), 1.30 (m, 2H), 1.60 (s, 3H), 2.08 (m, 2H), 2.37 (d,
j = 10.00 Hz, 1H), 5.54 (m, 1H), 6.40 (d, j = 16.00 Hz, 1H),
6.80 (dd, j = 16.00, 10.00 Hz, 1H), 7.10 (d, j = 16.00 Hz, 1H),
7.62 (m, 2H), 7.72 (d, j = 16.00 Hz, 1H), 8.26 (d, j = 8.00 Hz,
2H). 13C NMR (CDCl3, 200 MHz) δ 23.264 (q), 23.454 (t),
27.223 (q), 28.339 (q), 31.564 (t), 33.137 (s), 55.069 (d),
123.346 (d), 124.550 (d), 2 × 128.581 (d), 2 × 129.220 (d),
130.864 (d), 132.131 (s), 140.229 (d), 141.508 (s), 148.867
(s), 150.606 (d), 188.471 (s). MS: (m/e) 325 (M+ + 1).
2.30 (d, j = 10.00 Hz, 1H), 3.85 (s, 9H), 5.50 (m, 1H), 6.40 (d,
j = 16.00 Hz, 1H), 6.80 (m, 4H), 7.60 (d, j = 16.00 Hz, 1H). 13
C
NMR (CDCl3, 200 MHz) δ 23.295 (t), 23. 464 (q), 27.277 (q),
28.268 (q), 31.619 (t), 33.080 (s), 54.986 (d), 2 × 56.618 (q),
61.361 (q), 2 × 106.006 (d), 109.977 (s), 123.060 (d), 124.971
(d), 130.533 (d), 130.737 (s), 132.421 (s), 140.754 (s), 143.526
(d), 149.157 (d), 153.863 (s), 189.034 (s). MS: (m/e) 371 (M+
+ 1).
5.1.2. 1-(4-Chlorophenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2′-en-
1′-yl)-pent-1,4-dien-3-one (3c)
Yield: 80%. M.p. 86–87 °C. IR (KBr, cm−1) 2960, 2924,
1
5.1.6. 1-(2-Nitro-phenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2-en-1′-
yl)-pent-1,4-dien-3-one (3g)
2869, 1658, 1598. H NMR (CDCl3, 200 MHz) δ 0.90 (s,
3H), 0.95 (s, 3H), 1.20 (m, 2H), 1.55 (s, 3H), 2.05 (m, 2H),
2.30 (d, j = 10.00 Hz, 1H), 5.50 (m, 1H), 6.35 (d, j = 16.00 Hz,
1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 7.00 (d, j = 16.00 Hz,
1H), 7.50 (dd, 4H), 7.65 (d, j = 16.00 Hz, 1H). 13C NMR
(CDCl3, 200 MHz) δ 23.277 (q), 23.464 (t), 27.259 (q)
28.301 (q), 31.614 (t), 33.093 (s), 55.016 (d), 123.145 (d),
125.549 (d), 2 × 129.590 (d), 2 × 129.854 (d), 130.943 (d),
Yield: 73%. M.p. 115–117 °C. IR (KBr, cm−1) 2968, 2911,
1638, 1558, 1509. 1H NMR (CDCl3, 200 MHz) δ 0.88 (s, 3H),
0.98 (s, 3H), 1.20 (m, 2H), 1.60 (s, 3H), 2.00 (m, 2H), 2.35 (d,
j = 10.00 Hz, 1H), 5.52 (m, 1H), 6.40 (d, j = 16.00 Hz, 1H),
6.86 (dd, j = 16.00, 10.00 Hz, 1H), 7.54 (d, j = 16.00 Hz, 1H),
7.67 (m, 2H), 7.72 (d, j = 16.00 Hz, 1H), 8.00 (d, j = 8.00 Hz,

N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
783
2H). 13C NMR (CDCl3, 200 MHz) δ 23.205 (q), 23.426 (t),
27.181 (q) 28.260 (q), 31.540 (t), 33.044 (s), 55.020 (d),
123.190 (d), 125.301 (d), 129.506 (d), 130.641 (d), 132.190
(s), 133.904 (d), 134.107 (d), 134.450 (d), 138.447 (d),
141.508 (s), 148.893 (s), 150.606 (d), 188.918 (s). MS: (m/e)
325 (M+ + 1).
j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.45 (d, 2H), 7.95 (d, 2H). 13C NMR (CDCl3,
200 MHz) δ 23.393 (q), 23.537 (t), 27.301 (q), 28.379 (q),
31.741 (t), 33.088 (s), 55.139 (d), 105.115 (d), 122.447 (d),
2 × 128.738 (d), 2 × 129.276 (d), 130.453 (d), 133.345 (s),
136.542 (s), 136.829 (s), 141.279 (s), 163.785 (s) 164.855
(s), 165.052 (s). MS: (m/e) 354 (M+ + 1).
5.1.7. 1-(3-Nitro-phenyl)-5-(2′,6′,6′-trimethyl-cyclohex-2-en-1′-
yl)-pent-1,4-dien-3-one (3h)
5.2.2. 4-(4-Chloro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-ylamine (4c)
Yield: 70%. M.p. 122–124 °C. IR (KBr, cm−1) 2977, 2908,
1638, 1567, 1509. 1H NMR (CDCl3, 200 MHz) δ 0.89 (s, 3H),
0.96 (s, 3H), 1.30 (m, 2H), 1.60 (s, 3H), 2.00 (m, 2H), 2.37 (d,
j = 10.00 Hz, 1H), 5.54 (m, 1H), 6.39 (d, j = 16.00 Hz, 1H),
6.88 (dd, j = 16.00, 10.00 Hz, 1H), 7.28 (d, j = 16.00 Hz, 1H),
7.68 (d, j = 16.00 Hz, 1H), 7.87 (d, j = 16.00 Hz, 2H), 8.23 (d,
j = 8.00 Hz, 2H). 13C NMR (CDCl3, 200 MHz) δ 23.257 (q),
23.449 (t), 27.230 (q) 28.333 (q), 31.574 (t), 33.127 (s), 55.073
(d), 122.719 (d), 123.312 (d), 124.847 (d), 127.535 (d),
130.352 (d), 130.943 (d), 132.164 (s), 134.483 (d), 137.113
(s), 140.314 (d), 149.128 (s), 150.395 (d), 188.484 (s). MS:
(m/e) 325 (M+ + 1).
Yield: 48%. M.p. 151–152 °C. IR (KBr, cm−1) 3324, 3174,
1565, 1364, 1092. 1H NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H),
0.95 (s, 3H), 1.25 (m, 2H), 1.60 (s, 3H), 2.05 (m, 2H), 2.30 (d,
j = 10.00 Hz, 1H), 5.10 (m, 2H), 5.45 (m, 1H), 6.30 (d,
j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.45 (d, 2H), 7.95 (d, 2H). 13C NMR (CDCl3,
200 MHz) δ 23.393 (q), 23.537 (t), 27.301 (q), 28.379 (q),
31.741 (t), 33.088 (s), 55.139 (d), 105.115 (d), 122.447 (d),
2 × 128.738 (d), 2 × 129.276 (d), 130.453 (d), 133.345 (s),
136.542 (s), 136.829 (s), 141.279 (d), 163.785 (s) 164.855
(s), 165.052 (s). MS: (m/e) 354 (M+ + 1). Analysis calculated
for C21H24N3Cl: C, 71.37, H, 6.84, N, 11.89, Cl, 10.03. Found:
C, 71.60, H, 6.99, N, 12.17, Cl, 10.22.
5.2. General procedure for the synthesis of 4-(3,4-dimethoxy-
phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-enyl)-ethenyl]-
pyrimidin-2-ylamine (4a)
5.2.3. 4-(4-Fluro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-ylamine (4d)
Yield: 46%. M.p. 149–150 °C. IR (KBr, cm−1) 3338, 3175,
1572, 1364, 1160. 1H NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H),
0.95 (s, 3H), 1.25 (m, 1H), 1.50 (m, 1H), 1.59 (s, 3H), 2.05 (m,
2H), 2.33 (d, 1H), 5.29 (m, 2H), 5.30 (m, 1H), 6.29 (d,
j = 16.00 Hz, 1H), 6.79 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.12 (m, 2H), 7.99 (m, 2H). 13C NMR (CDCl3,
200 MHz) δ 23.395 (q), 23.536 (t), 27.295 (q), 28.381 (q),
31.737 (t), 33.069 (s), 55.137 (d), 104.978 (d), 115.812 (d),
116.244 (d), 122.426 (d), 2 × 129.345 (d), 130.504 (d),
2 × 133.372 (s), 134.226 (s), 141.109 (d), 163.846 (s)
164.921 (s), 165.029 (s). MS: (m/e) 338 (M+ + 1).
To a solution of sodium isopropoxide (prepared by dissol-
ving sodium metal 0.23 g in 20 ml of dry isopropanol) was
added guanidine hydrochloride (0.95 g, 10 mmol) and stirred
the reaction mixture for 3 h at room temperature. To the filtrate
was added 3a (3.86 g, 10 mmol) and silver oxide (4.64 g,
20 mmol) and the reaction mixture was refluxed at
100–110 °C for 16 h. It was filtered through celite and the
filtrate was extracted with ethylacetate (25 ml × 2). Combined
extract was washed with water (25 ml × 2), brine solution
(25 ml), dried (Na2SO4) and the solvent was removed in vacuo.
The crude product was column chromatographed (SiO2, 60–
120 mesh). Elution with 20% ethylacetate in hexane furnished
4a as a white crystalline solid (1.59 g, 42%). M.p 101–102 °C.
IR (KBr, cm−1) 3177, 2957, 1569, 1522, 1354. 1H NMR
(CDCl3, 200 MHz) δ 0.90 (s, 3H), 0.95 (s, 3H), 1.24 (m,
2H), 1.62 (s, 3H), 2.05 (m, 2H), 2.34 (d, j = 8.00 Hz, 1H),
3.93 (s, 3H), 3.97 (s, 3H), 5.02 (m, 2H), 5.94 (m, 1H), 6.30
(d, j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 2H), 7.60 (m, 2H). 13C NMR (CDCl3, 200 MHz) δ 23.214
(q), 23.349 (t), 27.118 (q), 28.167 (q), 31.559 (t), 32.884 (s),
54.937 (d), 56.187 (q), 56.240 (q), 104.727 (d), 110.217 (d),
111.133 (d), 120.259 (d), 122.153 (d), 130.435 (d), 130.670
(s), 133.276 (s), 140.449 (d), 149.408 (s), 151.342 (s),
163.507 (s), 154.323 (s), 165.462 (s). MS: (m/e) 380 (M+ + 1).
5.2.4. 4-(4-Benzyloxy-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-
2-enyl)-ethenyl]-pyrimidin-2-ylamine (4e)
Yield: 40%. M.p. 110–111 °C. IR (KBr, cm−1) 3019, 2923,
1574, 1530, 1371. 1H NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H),
0.95 (s, 3H), 1.30 (m, 2H), 1.70 (s, 3H), 2.40 (d, j = 10.00 Hz,
1H), 5.10 (m, 2H), 5.15 (s, 2H) 5.50 (m, 1H), 6.30 (d,
j = 16.00 Hz, 1H), 6.75 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.05 (d, j = 9.00 Hz, 2H), 7.40 (m, 5H), 8.00 (d,
j = 9.00 Hz, 2H). 13C NMR (CDCl3, 200 MHz) δ 23.451 (q),
23.574 (t), 27.347 (q), 28.410 (q), 31.782 (t), 33.086 (s),
55.154 (d), 104.647 (d), 2 × 115.374 (d), 122.371 (d),
2 × 127.905 (d), 128.489 (d), 129.038 (d), 4 × 130.701 (d),
133.492 (s), 137.078 (s), 140.687 (d), 161.131 (s), 163.837
(s), 164.562 (s), 165.641 (s). MS: (m/e) 426 (M+ + 1).
5.2.1. 4-(3,4,5-Trimethoxy-phenyl)-6-[2-(2,6,6-trimethyl-
cyclohex-2-enyl)-ethenyl]-pyrimidin-2-ylamine (4b)
Yield: 45%. M.p. 124–125 °C. IR (KBr, cm−1) 3399, 2957,
1565, 1364, 1092. 1H NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H),
0.95 (s, 3H), 1.25(m, 2H), 1.60 (s, 3H), 2.05 (m, 2H), 2.30 (d,
j = 10.00 Hz, 1H), 5.00 (m, 2H), 5.45 (m, 1H), 6.30 (d,
5.2.5. 4-{4-(3,4-Dimethoxy-phenyl)-6-[2-(2,6,6-trimethyl-
cyclohex-2-enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4f)
Yield: 38%. M.p. 123–125 °C. IR (KBr, cm−1) 2954, 2849,
1572, 1541, 1357. 1H NMR (CDCl3, 200 MHz) δ 0.95 (s, 3H),

784
N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
1.00 (s, 3H), 1.30 (m, 2H), 1.60 (s, 3H), 2.10 (m, 2H), 2.40 (d,
j = 10.00 Hz, 1H), 3.90 (m, 4H), 3.95 (s, 3H), 4.00 (s, 4H),
5.55 (m, 1H), 6.35 (d, j = 16.00 Hz, 1H), 6.85 (dd, j = 16.00,
10.00 Hz, 1H), 6.90 (s, 1H), 7.00 (d, j = 8.00 Hz, 1H), 7.70 (d,
j = 8.00 Hz, 1H), 7.70 (s, 1H). 13C NMR (CDCl3, 200 MHz) δ
24.258 (q), 24.546 (t), 28.573 (q), 29.475 (q), 33.194 (t),
34.345 (s), 2 × 46.091 (t), 56.293 (d), 57.313 (q), 57.467 (q),
2 × 68.697 (t), 104.864 (d), 111.708 (d), 112.892 (d), 121.778
(d), 123.3907 (d), 132.425 (d), 132.592 (s), 134.968 (s),
141.295 (d), 150.776 (s), 152.777 (s), 163.760 (s), 165.099
(s), 165.974 (s). MS: (m/e) 450 (M+ + 1).
147.194 (d), 159.675(s), 161.098 (s), 162.472 (s), 163.154
(s). MS: (m/e) 496 (M+ + 1).
5.2.9. 4-{4-(4-Fluro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4j)
1
Yield: 49%. IR (KBr, cm−1) 2920, 2959, 1544, 1363. H
NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H), 0.95 (s, 3H), 1.27
(m, 1H), 1.60 (s, 3H), 2.06 (m, 2H), 2.34 (d, j = 10.00 Hz,
1H), 3.79 (m, 4H), 3.88 (m, 4H), 5.50 (m, 1H), 6.31 (d,
j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.12 (m, 2H), 8.04 (m, 2H). 13C NMR (CDCl3,
200 MHz) δ 23.438 (q), 23.549 (t), 27.387 (q), 28.223 (q),
31.932 (t), 33.085 (s), 2 × 44.793 (t), 55.047 (d), 2 × 67.409
(t), 103.591 (d), 116.116 (d), 116.668 (d), 122.276 (d),
129.260 (d), 129.429 (d), 130.642 (d), 131.086 (s), 133.616
(s), 134.636 (s), 140.422 (d), 162.512 (s) 164.012 (s),
164.250 (s). MS: (m/e) 408 (M+ + 1).
5.2.6. 4-{4-(3,4,5-Trimethoxy-phenyl)-6-[2-(2,6,6-trimethyl-
cyclohex-2-enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4g)
Yield: 40%. M.p. 123–125 °C. IR (KBr, cm−1) 2960, 2856,
1542, 1502, 1357. 1H NMR (CDCl3, 200 MHz) δ 0.95 (s, 3H),
1.00 (s, 3H), 1.30 (m, 2H), 1.60 (s, 3H), 2.10 (m, 2H), 2.40 (d,
j = 10.00 Hz, 1H), 3.90 (m, 4H), 3.95 (s, 3H), 4.00 (s, 4H),
5.55 (m, 1H), 6.35 (d, j = 16.00 Hz, 1H), 6.85 (dd, j = 16.00,
10.00 Hz, 1H), 6.90 (s, 1H), 7.00 (d, j = 8.00 Hz, 1H), 7.70 (d,
j = 8.00 Hz, 1H), 7.70 (s, 1H). 13C NMR (CDCl3, 200 MHz) δ
23.244 (q), 23.427 (t), 27.248 (q), 28.168 (q), 31.885 (t),
33.040 (s), 2 × 44.790 (t), 53.849 (d), 54.981 (q), 56.561 (q),
56.678 (q), 2 × 67.334 (t), 104.065 (d), 104.962 (d), 122.235
(d), 131.022 (d), 133.569 (s), 133.978 (s), 140.202 (d),
140.717 (s), 153.745 (s), 153.841 (s), 162.406 (s), 163.911
(s), 164.835 (s). MS: (m/e) 480 (M+ + 1).
5.2.10. 4-(4-Nitro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-ylamine (4k)
Yield: 48%. M.p. 176–178 °C. IR (KBr, cm−1) 3166, 2955,
1570, 1546, 1345. 1H NMR (CDCl3, 200 MHz) δ 0.91 (s, 3H),
0.96 (s, 3H), 1.30 (m, 2H), 1.62 (s, 3H), 2.10 (m, 2H), 2.40 (d,
1H), 5.08 (m, 2H), 5.51 (s, 1H), 6.33 (d, j = 16.00 Hz, 1H),
6.90 (dd, j = 16.00, 10.00 Hz, 1H), 7.10 (s, 1H), 8.25 (dd, 4H).
13C NMR (CDCl3, 200 MHz) δ 23.382 (q), 23.531 (t), 27.277
(q), 28.401 (q), 31.705 (t), 33.114 (s), 55.158 (d), 105.896 (d),
122.596 (d), 2 × 124.241 (d), 2 × 128.342 (d), 130.168 (d),
133.189 (s), 142.074 (s), 144.108 (s), 149.323 (s), 163.504
(s) 163.848 (s), 165.586 (s). MS: (m/e) 365 (M+ + 1). Analysis
calculated for C21H24N4O2: C, 69.20, H, 6.63, N, 15.37.
Found: C, 69.89, H, 6.76, N, 15.48.
5.2.7. 4-{4-(4-Chloro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-
2-enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4h)
Yield: 45%. IR (KBr, cm−1) 3013, 2959, 1542, 1362, 1113.
1H NMR (CDCl3, 200 MHz) δ 0.90 (s, 3H), 0.96 (s, 3H), 1.25
(m, 2H), 1.60 (s, 3H), 2.10 (m, 2H), 2.35 (d, j = 10.00 Hz, 1H),
3.80 (m, 4H), 3.90 (m, 4H), 5.50 (m, 1H), 6.30 (d,
j = 16.00 Hz, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 6.90
(s, 1H), 7.40 (d, j = 8.00 Hz, 2H), 8.00 (d, j = 8.00 Hz, 2H).
13C NMR (CDCl3, 200 MHz) δ 23.444 (q), 23.544 (t), 27.390
(q), 28.236 (q), 31.922 (t), 33.092 (s), 2 × 44.782 (t), 55.049
(d), 67.162 (t), 67.400 (t), 103.664 (d), 122.302 (d),
2 × 128.690 (d), 2 × 129.163 (d), 130.036 (d), 133.583 (s),
136.663 (s), 136.942 (s), 140.556 (d), 162.571 (s), 163.861
(s), 164.365 (s). MS: (m/e) 424 (M+ + 1).
5.2.11. 4-{4-(4-Nitro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4l)
Yield: 43%. m.p. 194–196 °C. IR (KBr, cm−1) 2961, 1545,
1
1486, 1356. H NMR (CDCl3, 200 MHz) δ 0.91 (s, 3H), 0.96
(s, 3H), 1.30 (m, 2H), 1.65 (s, 3H), 2.10 (m, 2H), 2.40 (d,
j = 10.00 Hz, 1H), 3.80 (m, 4H), 4.00 (m, 4H), 5.55 (bs, 1H),
6.35 (d, j = 16.00 Hz, 1H), 6.85 (dd, j = 16.00, 10.00 Hz, 1H),
7.00 (s, 1H), 8.30 (dd, 4H). 13C NMR (CDCl3, 200 MHz) δ
23.435 (q), 23.545 (t), 27.364 (q), 28.275 (q), 31.877 (t),
33.122 (s), 2 × 44.754 (t), 55.077 (d), 2 × 67.360 (t), 104.391
(d), 122.459 (d), 2 × 124.170 (d), 2 × 128.258 (d), 130.768 (d),
133.421 (s), 141.351 (d), 144.549 (s), 149.262 (s), 162.508 (s)
162.590 (s), 164.899 (s). MS: (m/e) 435 (M+ + 1). Analysis
calculated for C25H30N4O3: C, 69.10, H, 6.95, N, 12.89.
Found: C, 69.31, H, 7.12, N, 13.14.
5.2.8. 4-{4-(4-Benzyloxy-phenyl)-6-[2-(2,6,6-trimethyl-
cyclohex-2-enyl)-ethenyl]-pyrimidin-2-yl}morpholine (4i)
Yield: 42%. IR (KBr, cm−1) 3014, 2958, 1596, 1538, 1361.
1H NMR (CDCl3, 200 MHz) δ 0.88 (s, 3H), 0.95 (s, 3H), 1.25
(m, 2H), 1.63 (s, 3H), 2.40 (d, j = 10.00 Hz, 1H), 3.80 (m, 4H),
3.90 (m, 4H), 5.10 (m, 2H), 5.12 (s, 2H) 5.50 (m, 1H), 6.37 (d,
j = 16.00 Hz, 1H), 6.75 (dd, j = 16.00, 10.00 Hz, 1H), 6.90 (s,
5.2.12. 4-(2-Nitro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
enyl)-ethenyl]-pyrimidin-2-ylamine (4m)
1H), 7.00 (d, j = 9.00 Hz, 2H), 7.35 (m, 5H), 8.00 (d, 2H). 13
C
NMR (CDCl3, 200 MHz) δ 22.050 (q), 22.140 (t), 25.878 (q),
26.825 (q), 30.261 (t), 31.639 (s), 43.394 (t), 53.563 (d),
66.019 (t), 69.088 (t), 101.897 (d), 113.841 (d), 114.267 (d),
121.822 (d), 2 × 126.424 (d), 127.026 (d), 127.117 (d),
127.628 (d), 129.011 (d), 129.679 (d), 129.843 (d), 131.115
(s), 132.294 (s), 135.696 (s), 138.532 (d), 141.728 (d),
Yield: 46%. M.p. 218–220 °C. IR (KBr, cm−1) 3310, 3196,
1575, 1535, 1363. 1H NMR (CDCl3, 200 MHz) δ 0.89 (s, 3H),
0.95 (s, 3H), 1.30 (m, 2H), 1.60 (s, 3H), 2.05 (m, 2H), 2.40 (d,
j = 10.00 Hz, 1H), 5.00 (m, 2H), 5.50 (bs, 1H), 6.30 (d,
j = 16.00 Hz, 1H), 6.75 (s, 1H), 6.85 (dd, j = 16.00,
10.00 Hz, 1H), 7.65 (m, 3H), 7.95 (d, j = 8.00 Hz, 1H). 13C

N. Chandra et al. / European Journal of Medicinal Chemistry 41 (2006) 779–785
785
NMR (CDCl3, 200 MHz) δ 23.393 (q), 23.511 (t), 27.284 (q),
Acknowledgements
28.375 (q), 31.700 (t), 33.105 (s), 55.101 (d), 107.279 (d),
122.500 (d), 124.784 (d), 130.114 (d), 130.261 (d), 131.115
(s), 132.900 (d), 133.244 (s), 141.975 (d), 149.342 (s),
163.294 (s), 164.871 (s), 165.199 (s). MS: (m/e) 365 (M+ +
1). Analysis calculated for C21H24N4O2: C, 69.20, H, 6.63,
N, 15.37. Found: C, 69.41, H, 6.70, N, 15.55.
Financial support to Naveen Chandra by MOH (India) and
Susmita Pandey by ICMR, New Delhi and technical support by
Mrs. Manju and Mr. Shiv Ram are gratefully acknowledged.
References
5.2.13. 4-{4-(2-Nitro-phenyl)-6-[2-(2,6,6-trimethyl-cyclohex-2-
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1
Yield: 40%. IR (KBr, cm−1) 3019, 2962, 1544, 1363. H
NMR (CDCl3, 200 MHz) δ 0.89 (s, 3H), 0.95 (s, 3H), 1.30
(bs, 2H), 1.70 (s, 3H), 2.10 (bs, 2H), 2.40 (d, j = 10.00 Hz,
1H), 3.80 (bs, 8H), 5.50 (bs, 1H), 6.30 (d, j = 16.00 Hz, 1H),
6.70 (s, 1H), 6.80 (dd, j = 16.00, 10.00 Hz, 1H), 7.60 (m, 3H),
8.00 (d, 1H). 13C NMR (CDCl3, 200 MHz) δ 23.420 (q),
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2 × 44.646 (t), 55.023 (d), 2 × 67.293 (t), 105.439 (d),
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Yield: 41%. IR (KBr, cm−1) 2958, 2922, 1540, 1352. H
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1H), 3.80 (d, 4H), 3.95 (d, 4H), 5.52 (bs, 1H), 6.30 (d,
j = 16.00 Hz, 1H), 6.70 (dd, 1H), 6.90 (s, 1H), 7.63 (m, 3H),
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enyl)-ethenyl]-pyrimidin-2-ylamine (4p)
Yield: 44%. M.p. 202–204 °C. IR (KBr, cm−1) 3305, 3187,
1580, 1535, 1365. 1H NMR (CDCl3, 200 MHz) δ 0.98 (s, 3H),
0.95 (s, 3H), 1.25 (m, 2H), 1.659 (s, 3H), 2.00 (bs, 2H), 2.42
(d, j = 10.00 Hz, 1H), 5.50 (bs, 1H), 6.35 (d, j = 16.00 Hz, 1H),
6.73 (dd, 1H), 6.88 (s, 1H), 7.61 (m, 3H), 8.21 (dd, 1H). MS:
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