Ceric ammonium nitrate (CAN): An efficient and eco-friendly catalyst for the one-pot synthesis of alkyl/aryl/heteroaryl-substituted bis(6-aminouracil-5-yl)methanes at room temperature

Article abstract of DOI:10.1039/c5ra04723d

A simple, facile and convenient practical method for the one-pot synthesis of biologically relevant alkyl/aryl/heteroaryl-substituted bis(6-aminouracil-5-yl)methane scaffolds (3a-3u) has been developed using ceric ammonium nitrate (CAN) as a commercially

Full text of DOI:10.1039/c5ra04723d

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Ceric ammonium nitrate (CAN): an efficient and
eco-friendly catalyst for the one-pot synthesis of
alkyl/aryl/heteroaryl-substituted bis(6-
Cite this: RSC Adv., 2015, 5, 39263
aminouracil-5-yl)methanes at room temperature†
*
Goutam Brahmachari and Bubun Banerjee
A simple, facile and convenient practical method for the one-pot synthesis of biologically relevant alkyl/aryl/
heteroaryl-substituted bis(6-aminouracil-5-yl)methane scaffolds (3a–3u) has been developed using ceric
ammonium nitrate (CAN) as a commercially available and eco-friendly catalyst via pseudo three-
component condensation reaction between aldehydes and 6-aminouracils in aqueous ethanol at room
temperature. The salient features of the present protocol are mild reaction conditions, good to excellent
yields, high atom-economy, environmentally benignity, easy isolation of products, no column
chromatographic separation and reusability of reaction media.
Received 17th March 2015
Accepted 16th April 2015
DOI: 10.1039/c5ra04723d
www.rsc.org/advances
merits of their own, still they suffer from a number of demerits
such as long reaction time, heating reaction conditions, and
Introduction
use of toxic organic solvents. Therefore, a search for more
general, clean, efficient, and high yielding routes for the
synthesis of alkyl/aryl/heteroaryl-substituted bis(6-aminouracil-
5-yl)methanes remains a valid exercise.
6-Aminouracil is a ‘privileged’ structural motif, and is very
common in bioactive natural products, and regarded as a
versatile building block for the several bioactive nitrogen-
containing heterocycles.1 This scaffold acts as an intermediate
for the synthesis of many purine-based drugs, such as caffeine,
theobromine, penciclovir, and theophylline.2 In medicinal
chemistry, 6-aminouracils are the important starting
compounds for the synthesis of xanthenes and theophylline-
related compounds3 which are now routinely used as a phos-
phodiesterase inhibitors for the treatment of asthma.4
Pyrimidine-containing organic scaffolds are known to exhibit
diverse biological and pharmaceutical activities as well.5
Heterocycles, particularly bearing a pyrimidine moiety, such as
dihydropyrimidines,6 furopyrimidines,7 and pyrazolopyr-
imidines,8 are regarded as scaffolds of pharmaceutical promise
due to their several biological efficacies.9
Ceric ammonium nitrate (CAN) is a commercially available,
inexpensive, and eco-friendly substance that has found huge
applications in organic transformations in recent years due to
its Lewis acidic property, high reactivity, excellent solubility in
water and easy work-up procedures. This unique catalyst has
been found to be effective in the synthesis of a variety of bio-
logically relevant heterocycles, viz. 2,4,5-triaryl-1H-imidazoles,14
indeno[1,2-b]pyridines,15 pyrano[2,3-d]pyrimidine-2,4,7-tri-
ones,16 N-substituted decahydroacridine-1,8-diones,17 pyrrole-
2,3,4,5-tetracarboxylates18 and many more.19 Such successful
catalytic performance of CAN has encouraged us to investigate
on its further application in other carbon–carbon bond forming
reactions. In this paper, we wish to extend the synthetic appli-
cability of this unique catalyst in the one-pot synthesis of alkyl/
aryl/heteroaryl-substituted bis(6-aminouracil-5-yl)methanes (3).
In recent times, multicomponent reactions (MCRs) have
gained eminence as a synthetic tool for producing structurally
complex molecular entities with attractive biological features
through the formation and breakage of several carbon–carbon
and carbon–heteroatom bonds in one-pot.20 It is becoming
increasingly important both in academia and in industry to
design less toxic and more environmentally friendly MCRs. In
addition, implementation of several transformations in a single
manipulation in MCR strategy is highly compatible with the
goals of sustainable and “green” chemistry.21
In spite of a handful of diverse applications of alkyl/aryl/
heteroaryl-substituted
bis(6-aminouracil-5-yl)methanes
in
medi-cinal chemistry, there are only a few methods are available
so far for their synthesis involving a pseudo three-component
tandem reaction between uracils and aldehydes in the pres-
ence of catalysts such as acetic acid,10 TEBAC,11 sulfuric acid
functionalized silica (SSA)12 and also using microwave irradia-
tion.13 Although these protocols reported by others nd certain
Laboratory of Natural Products & Organic Synthesis, Department of Chemistry,
Visva-Bharati University, Santiniketan-731 235, West Bengal, India. E-mail:
brahmg2001@yahoo.co.in; brahmg2001@gmail.com; Fax: +91-3463-261526; Tel:
+91-3463-261526
† CCDC 968994. For crystallographic data in CIF or other electronic format see
DOI: 10.1039/c5ra04723d
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Scheme 1 One-pot synthesis of substituted bis(6-aminouracil-5-yl)methanes.
Table 1 Optimization of reaction conditions
Entry
Catalyst (mol%)
Solvent
Time (h)
Yielda,b (%)
1
2
3
4
5
6
7
8
No catalyst
No catalyst
No catalyst
CAN (10 mol%)
CAN (10 mol%)
CAN (10 mol%)
CAN (10 mol%)
CAN (15 mol%)
CAN (5 mol%)
I2 (10 mol%)
NaCl (10 mol%)
CH3COONa (10 mol%)
NH4Cl (10 mol%)
Fe(NO3)3$6H2O (10 mol%)
NiCl2$6H2O (10 mol%)
CuCl2$2H2O (10 mol%)
(NH4)4Ce(SO4)4$2H2O (10 mol%)
No solvent
H2O
EtOH
EtOH
24
24
10
4
10
2
10
2
3.5
2
2
2
2
2
2
2
2
Trace
38
42
71
56
89
36
91
84
59
0
0
0
52
44
34
48
H2O
EtOH : H2O (1 : 1 v/v)
No solvent
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
EtOH : H2O (1 : 1 v/v)
9
10
11
12
13
14
15
16
17
a
Experimental conditions: 6-amino-1,3-dimethyluracil (1, 1 mmol) and benzaldehyde (2, 0.5 mmol) in the presence or absence of different catalysts
b
in neat/4 mL of various solvent systems at room temperature. Isolated yields.
In continuation of our sincere efforts to develop green
synthetic methodologies for organic transformations,22 we
Results and discussion
have recently developed a straightforward and efficient pseudo
three-component one-pot synthesis of alkyl/aryl/heteroaryl-
substituted bis(6-aminouracil-5-yl)methane derivatives in good
yields using commercially available CAN as inexpensive and
environmentally benign catalyst from the reaction of aldehydes
and 6-aminouracil derivatives in aqueous ethanol at room
temperature. The present method is not only cost-effective and
environmentally benign, but also experimentally safe and
simple, easy to handle, clean and efficient. The results are
summarized in Scheme 1 and Table 2.
We herein report on a straightforward energy-efficient and
high yielding protocol for the one-pot synthesis of a series
of biologically relevant alkyl/aryl/heteroaryl-substituted bis(6-
aminouracil-5-yl)methanes (3a–3u) in aqueous ethanol at
room temperature under the catalysis of CAN (Scheme 1). First,
we conducted a series of trial reactions using 6-amino-1,3-
dimethyluracil (1; R ¼ CH3; 1 mmol) and benzaldehyde (2; 0.5
mmol) in the absence or presence of different catalysts in
aqueous ethanol (1 : 1 v/v) at room temperature for obtaining
the best yield of the desired product, 5,50-(phenylmethylene)-
bis(6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione) (3a). It
appeared that 10 mol% of CAN in aqueous ethanol (1 : 1 v/v) at
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Table 2 Synthesis of substituted bis(6-aminouracil-5-yl)methanes (3a–3u)
CAN (10 mol%)
Melting point (ꢀC)
Entry
Product
R
Substituent (R1)
Time (h)
Yielda,b (%)
Found
Reported
1
2
3
4
5
6
7
8
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
3q
3r
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
C6H5
4-Cl-C6H4
4-F-C6H4
4-Br-C6H4
4-CH3-C6H4
4-CN-C6H4
2.0
4.0
8.0
4.0
3.0
5.0
6.0
7.0
2.0
5.0
7.0
6.0
8.0
5.0
3.0
2.0
8.0
6.0
6.0
2.0
4.0
89
92
81
91
86
87
89
86
90
82
87
88
94
90
87
94
79
82
84
86
89
257–259
260–262
263–265
264–266
274–276
286–287
270–272
282–283
244–246
261–263
259–260
270–272
236–237
237–238
246–248
245–246
251–253
232–234
231–233
293–295
299–300
260–262 (ref. 11)
<300 (ref. 13)
264–265 (ref. 23)
—
<300 (ref. 10)
—
—
<300 (ref. 13)
248–250 (ref. 13)
—
—
268–270 (ref. 11)
238–240 (ref. 11)
240–242 (ref. 11)
—
—
—
—
—
—
—
4-OCH3-C6H4
4-NO2-C6H4
3-NO2-C6H4
2-NO2-C6H4
2-Cl-C6H4
3,4,5-(OCH3)3-C6H2
3,4-OCH2O-C6H3
3-OCH3-4-OH-C6H3
3,4-(OH)2-C6H3
2-Furfuryl
2-OH-5-Cl-C6H3
4-OH-C6H4
(CH3)2CH
C6H5
3,4,5-(OCH3)3-C6H2
9
10
11
12
13
14
15
16
17
18
19
20
21
3s
3t
3u
H
a
Experimental conditions: 6-aminouracil (1, 1 mmol), aldehyde (2, 0.5 mmol) and 10 mol% CAN as catalyst in 4 mL of aqueous ethanol (1 : 1 v/v) at
b
room temperature. Isolated yields.
room temperature provides the best result in terms of yield and low yield of 36% at 10 h. The overall results are summarized in
time (Table 1, entry 6) to obtain 3a, which was characterized by Table 1.
its physical and spectral properties.11 Under solvent-free
Aer optimizing the reaction conditions, the reaction of 4-
conditions with 10 mol% of CAN, the product was obtained in chlorobenzaldehyde with 6-amino-1,3-dimethyluracil was carried
out under the same reaction conditions and it furnished the
Fig. 1 (a) ORTEP diagram of compound 3p.† (b) The packing arrangement of molecules viewed down the b-axis.
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product 3b in 92% yield with CAN within 4 h (Table 2, entry 2). nucleophilic attack by 6-aminouracil (1) to the electron-
To check the generality as well as the effectiveness of our newly decient carbonyl centre of 2 through electron-rich C-5 posi-
developed protocol, a number of aromatic aldehydes having tion, thereby generating an intermediate 6, which then reacts
substituents such as hydroxy, methoxy, nitro, halogens, with the second molecule of 1 under the inuence of CAN in
aliphatic and heteroaryl aldehydes such as isobutaraldehyde aqueous ethanol to afford the desired product 3 (Scheme 2).
and furfural, respectively, were reacted with 6-amino-1,3-
It is worth-noting that we reused the ltrate containing
dimethyluracil using identical reaction conditions, and all of residual solvent, catalyst and substrates obtained upon ltra-
them underwent the reaction smoothly affording the corre- tion of the reaction mixture aer completion of the reaction up
sponding bis(6-amino-1,3-dimethyluracil-5-yl)methanes (3c–3s) to 3rd times in case of a representative entry (entry 1; Table 2);
(Table 2, entries 3–20) in good to excellent yields (79–94%) at addition of reactants directly into the ltrate without adding
room temperature. Encouraged by these results, we attempted further catalyst resulted in the formation of expected product 3a
to extend the present protocol with 6-amino-1-methyluracil without appreciable loss of catalytic activity at least up to 3rd run
(1; R ¼ H) which also underwent smooth reactions with alde- (with respective isolated yields of 89%, 81% and 74%). However,
hydes under the same optimized reaction conditions affording each ltrate can only be used for the particular entry due to the
the corresponding products 3t–3u (Table 2, entries 20–21) in presence of residual starting materials.
excellent yields (86–89%). The overall results are summarized in
Table 2.
Conclusions
All the products were isolated pure just by washing with cold
aqueous ethanol followed by recrystallization from ethanol; no
tedious chromatographic purication was required. The iso-
In conclusion, we have developed a very simple, facile and
convenient practical method for one-pot synthesis of biologi-
cally relevant alkyl/aryl/heteroaryl-substituted bis(6-aminouracil-
5-yl)methane scaffolds (3a–3u) in the presence of CAN as a
lated products were fully characterized on the basis of their
analytical data and detailed spectral studies including FT-IR, 1H
NMR, 13C NMR and TOF-MS. All the known compounds had
commercially available and eco-friendly catalyst via pseudo
physical and spectroscopic data identical to those reported in
three-component condensation reaction between aldehydes
literature.10,11,13,23 Single crystal X-ray analysis for 5,50-(furan-2-yl-
and 6-aminouracils in aqueous ethanol at room temperature.
Mild reaction conditions, good to excellent yields, operational
simplicity and absence of tedious separation procedures, clean
reaction prole, high atom-economy as well as the use of inex-
methylene)bis(6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-
dione) (3p) (Table 2, entry 16) was also documented in this
present communication (Fig. 1).24
We herein propose a mechanism for the formation of
pensive and environmentally benign catalyst are the key
substituted bis(6-aminouracil-5-yl)methane entity. CAN as a
advantages of the present method. Moreover, reusability of the
Lewis acid activates aldehyde molecule (2) and thus facilitates a
reaction media without signicant loss of activity is an added
Scheme 2 Proposed mechanism for the synthesis of substituted bis(6-aminouracil-5-yl)methanes.
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advantage. Keeping in view of the synthetic importance of such 2228, 1684, 1601, 1499, 1379, 1337, 1252, 1144, 1059, 939, 872,
bis(6-aminouracil-5-yl)methane derivatives of pharmaceutical 714; 1H NMR (400 MHz, DMSO-d6): dH 7.63 (br s, 4H, 2ꢂ –NH2),
potential, the current methodology with mild reaction condi- 7.35 (m, 4H, ArH), 5.63 (s, 1H, –CH–), 3.39 (s, 6H, 2ꢂ NCH3), 3.17
tions and operational simplicity offers the possibility of its use (s, 6H, 2ꢂ NCH3). 13C NMR (100 MHz, DMSO-d6): dC 163.85 (2C),
with cost-effective and environmentally friendlier ways for 155.27 (2C), 150.84 (2C), 146.82, 132.00 (2C), 128.21 (2C),
large-scale syntheses.
119.65, 108.13, 86.44, 84.93, 36.23 (2C), 30.42 (2C), 28.40. TOF-
MS: 446.1549 [M + Na]+. Anal. calcd for C20H21N7O4: C 56.73, H
5.00, N 23.16; found: C 56.77, H 4.98, N 23.22.
Experimental
General
5,50-((4-Methoxyphenyl)methylene)bis(6-amino-1,3-dime-
thylpyrimidine-2,4(1H,3H)-dione) (3g). White solid, yield 89%.
Mp: 270–272 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3408, 3196, 3045, 3026,
2953, 2829, 2799, 1691, 1655, 1578, 1504, 1466, 1452, 1375,
1348, 1248, 1213, 1161, 1115, 1057, 1038, 928, 835, 793, 750; 1H
NMR (400 MHz, DMSO-d6) dH 7.39 (br s, 4H, 2ꢂ –NH2), 6.97 (br
s, 2H, ArH), 6.76 (br s, 2H, ArH), 5.53 (s, 1H, –CH–), 3.67 (s, 3H,
–OCH3), 3.32 (s, 6H, 2ꢂ NCH3), 3.14 (s, 6H, 2ꢂ NCH3); 13C NMR
(100 MHz, DMSO-d6): dC 164.00, 162.58, 157.21, 155.06, 154.12,
150.87 (2C), 131.55, 127.94 (2C), 113.46 (2C), 87.09, 85.95, 55.26,
34.94 (2C), 30.34 (2C), 28.36; TOF-MS: 451.1701 [M + Na]+; anal.
calcd for C20H24N6O5: C, 56.07; H, 5.65; N, 19.62; found: C,
56.01; H, 5.68; N, 19.59.
Infrared spectra were recorded using a Shimadzu (FT-IR 8400S)
FT-IR spectrophotometer using KBr disc. 1H and 13C NMR
spectra were obtained at 400 MHz and 100 MHz respectively,
using Bruker DRX-400 spectrometer and DMSO-d6 as the
solvent. Mass spectra (TOF-MS) were measured on a QTOF
Micro mass spectrometer. Elemental analyses were performed
with an Elementar Vario EL III Carlo Erba 1108 micro-analyzer
instrument. Melting point was recorded on a Chemiline CL-726
melting point apparatus and is uncorrected. Thin Layer Chro-
matography (TLC) was performed using silica gel 60 F254
(Merck) plates.
5,50-((2-Nitrophenyl)methylene)bis(6-amino-1,3-dimethyl-
pyrimidine-2,4(1H,3H)-dione) (3j). Yellowish solid, yield 82%;
mp 261–263 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3448, 3174, 2953, 1690,
1668, 1603, 1505, 1455, 1380, 1248, 1160, 1061, 913, 861, 784,
760; 1H NMR (400 MHz, DMSO-d6): dH 7.56 (br s, 2H, ArH), 7.52
(br s, 2H, ArH), 7.39 (br s, 4H, 2ꢂ –NH2), 7.21 (br s, 2H, ArH),
6.09 (s, 1H, –CH–), 3.31 (s, 6H, 2ꢂ NCH3), 3.23 (s, 3H, NCH3),
2.99 (s, 3H, NCH3). 13C NMR (100 MHz, DMSO-d6): dC 163.75,
162.24, 154.86, 154.52, 150.70, 150.06, 133.75, 131.85, 129.09,
127.14, 123.89 (2C), 86.14, 84.06, 32.58, 30.59, 30.32, 28.70,
28.04. TOF-MS: 466.1447 [M + Na]+. Anal. calcd for C19H21N7O6:
C 51.47, H 4.77, N 22.11; found: C 51.46, H 4.79, N 22.13.
5,50-((2-Chlorophenyl)methylene)bis(6-amino-1,3-dimethyl-
pyrimidine-2,4(1H,3H)-dione) (3k). White solid, yield 87%; mp
259–260 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3397, 3374, 3145, 2996, 2948,
1668, 1651, 1609, 1582, 1498, 1450, 1380, 1287, 1263, 1149,
1045, 963, 931, 825, 789; 1H NMR (400 MHz, DMSO-d6): dH 7.53
(br s, 2H, ArH), 7.35–7.19 (m, 4H, –NH2 + 2ꢂ ArH), 6.99 (2H, br s,
–NH2), 5.55 (s, 1H, –CH–), 3.35 (s, 6H, 2ꢂ NCH3), 3.19 (s, 3H,
NCH3), 3.07 (s, 3H, NCH3); 13C NMR (100 MHz, DMSO-d6): dC
163.44, 162.35, 154.60, 154.10, 150.78 (2C), 138.75, 132.83,
129.81, 129.55, 127.58, 126.84, 86.94, 85.51, 35.11 (2C), 30.44,
General procedure for the synthesis of aryl/alkyl/heteroaryl-
substituted bis(6-aminouracil-5-yl)methane derivatives
An oven-dried screw cap test tube was charged with a magnetic
stir bar, 6-aminouracils (1, 1 mmol) and aldehydes (2,
0.5 mmol), CAN (10 mol%) and EtOH : H2O (1 : 1 v/v; 4 mL) in a
sequential manner; the reaction mixture was then stirred
vigorously at room temperature. The progress of the reaction
was monitored by TLC. On completion of the reaction, a solid
mass precipitated out, ltered off and washed with cold aq.
ethanol to obtain crude product (3) which was then puried by
crystallization from ethanol. The ltrate containing residual
solvent, catalyst and substrates obtained upon ltration of the
reaction mixture aer completion of reaction could be
successfully reused for a particular entry up to 3rd times without
appreciable loss of the catalytic activity. The structure of each
puried product was conrmed by its analytical as well as
spectral studies including FT-IR, 1H NMR, 13C NMR and
TOF-MS.
Characterization data of all new compounds
5,50-((4-Bromophenyl)methylene)bis(6-amino-1,3-dimethylpyr- 28.62, 28.05; TOF-MS: 455.1207 [M + Na]+; anal. calcd for
imidine-2,4(1H,3H)-dione) (3d). White solid, yield 91%. Mp: 264–
C19H21ClN6O4: C 52.72, H 4.89, N 19.42; found: C 52.57, H 4.91,
266 ꢀC. IR (nmax/cmꢁ1, KBr): ¼ 3468, 3344, 3163, 3049, 2975, 1699, N 19.39.
1680, 1597, 1501, 1447, 1381, 1337, 1246, 1065, 929, 845, 779; 1H
5,50-((3,4-Dihydroxyphenyl)methylene)bis(6-amino-1,3-dime-
NMR (400 MHz, DMSO-d6): dH 7.36 (s, 6H, 2ꢂ –NH2, 2ꢂ –Ar–H), thylpyrimidine-2,4(1H,3H)-dione) (3o). White solid, yield 87%;
7.07 (m, 2H, ArH), 5.56 (s, 1H, –CH–), 3.34 (s, 6H, 2ꢂ NCH3), 3.16 mp 246–248 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3383, 2978, 1676, 1595,
(s, 6H, 2ꢂ NCH3). 13C NMR (100 MHz, DMSO-d6): dC 162.62 (2C), 1511, 1384, 1348, 1215, 1151, 1056, 870, 790; 1H NMR (400 MHz,
155.07 (2C), 150.85 (2C), 139.69, 130.83 (2C), 129.44 (2C), 118.29, DMSO-d6): dH 8.52 (s, 2H, –OH), 7.60 (s, 2H, –NH2), 7.30 (s, 2H,
85.27 (2C), 35.43 (2C), 30.38 (2C), 28.40. TOF-MS: 499.0701 –NH2), 6.55 (d, 1H, J ¼ 8.0 Hz, ArH), 6.48 (s, 1H, ArH), 6.33 (d,
[M + Na]+. Anal. calcd for C19H21BrN6O4: C 47.81, H 4.43, N 17.61; 1H, J ¼ 7.6 Hz, ArH), 5.46 (s, 1H, –CH–), 3.32 (s, 6H, 2ꢂ NCH3),
found: C 47.78, H 4.39, N 17.64.
3.15 (s, 6H, 2ꢂ NCH3). 13C NMR (100 MHz, DMSO-d6): dC 163.81,
4-(Bis(6-amino-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyri- 162.54, 154.81 (2C), 150.89 (2C), 145.01, 142.91, 130.56, 117.56,
midin-5-yl)methyl) benzonitrile (3f). White solid, yield 87%; mp 115.39, 114.54, 87.27, 86.02, 34.94 (2C), 30.35 (2C), 28.34. TOF-
286–287 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3423, 3323, 3115, 2945, 2893,
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MS: 453.1492 [M + Na]+. Anal. calcd for C19H22N6O6: C 53.02, H 162.91 (2C), 156.87 (2C), 151.69 (2C), 150.56, 140.01, 128.05
5.15, N 19.53; found: C 53.05, H 5.12, N 19.49.
(2C), 126.94 (2C), 125.28, 75.60 (2C), 34.35, 29.32, 28.63; TOF-
5,50-(Furan-2-ylmethylene)bis(6-amino-1,3-dimethylpyrimi- MS: 393.1284 [M + Na]+; anal. calcd for C17H18N6O4: C, 55.13;
dine-2,4(1H,3H)-dione) (3p). White solid, yield 94%; mp 245– H, 4.90; N, 22.69; found: C, 55.11; H, 4.88; N, 22.71.
246 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3356, 2918, 2876, 1685, 1584,
5,50-((3,4,5-Trimethoxyphenyl)methylene)bis(6-amino-1-
1
1499, 1359, 1276, 772; H NMR (400 MHz, DMSO-d6): dH 7.41 methylpyrimidine-2,4(1H,3H)-dione) (3u). White solid, yield
(5H, br s, ArH + 2ꢂ –NH2), 6.28 (1H, s, ArH), 6.03 (1H, d, J ¼ 1.2 89%; mp 299–300 C; IR (nmax/cmꢁ1, KBr): ¼ 3373, 3188, 2962,
ꢀ
Hz, ArH), 5.47 (1H, s, –CH–), 3.33 (6H, s, 2ꢂ NCH3), 3.15 (6H, s, 2829, 1711, 1585, 1508, 1393, 1308, 1238, 1132, 1065, 999, 859,
2ꢂ NCH3); 13C NMR (100 MHz, DMSO-d6): dC 163.06 (2C), 154.17 783, 725; H NMR (400 MHz, DMSO-d6): dH 10.84 (s, 1H, –NH),
1
(2C), 153.56, 150.78 (2C), 141.32, 110.30, 105.68, 85.76 (2C), 10.34 (s, 1H, –NH), 7.62 (s, 2H, –NH2), 7.22 (s, 1H, ArH), 6.82 (s,
31.70 (2C), 30.30 (2C), 28.30; TOF-MS: 411.1389 [M + Na]+; anal. 2H, –NH2), 6.36 (s, 1H, ArH), 4.58 (s, 1H, –CH–), 3.65 (s, 6H, 2ꢂ
calcd for C17H20N6O5: C, 52.57; H, 5.19; N, 21.64; found: C, –OCH3), 3.61 (s, 3H, –OCH3), 3.26 (s, 3H, –NCH3), 3.17 (s, 3H,
52.58; H, 5.22; N, 21.67.
–NCH3); 13C NMR (100 MHz, DMSO-d6): dC 162.98 (2C), 156.90
5,50-((5-Chloro-2-hydroxyphenyl)methylene)bis(6-amino-1,3- (2C), 152.72 (2C), 151.69, 150.56, 135.88, 135.64, 104.67 (2C),
dimethylpyrimidinꢀe-2,4(1H,3H)-dione) (3q). White solid, yield 75.59 (2C), 60.38, 56.24 (2C), 34.45, 28.63 (2C); TOF-MS:
79%; mp 251–253 C; IR (nmax/cmꢁ1, KBr): ¼ 3381, 3356, 3219, 483.1601 [M + Na]+; anal. calcd for C20H24N6O7: C 52.17, H
3072, 2951, 1695, 1601, 1493, 1256, 1119, 1047, 968, 933, 798, 5.25, N 18.25; found: C 52.14, H 5.23, N 18.29.
1
758; H NMR (400 MHz, DMSO-d6): dH 9.35 (s,1H, –OH), 7.26–
7.09 (m, 4H, ArH + –NH2), 6.99 (s, 2H, –NH2), 6.64 (s, 1H, ArH),
Acknowledgements
5.47 (s, 1H, –CH–), 3.35 (s, 3H, NCH3), 3.11 (s, 6H, 2ꢂ NCH3),
2.91 (s, 3H, NCH3); 13C NMR (100 MHz, DMSO-d6): dC 162.97,
161.61, 153.94, 153.56, 151.20, 150.81 (2C), 150.45, 129.72,
126.29, 122.28, 117.93, 90.19, 87.21, 32.32, 30.39 (2C), 29.26,
We are thankful to Visva-Bharati University and IICB, Kolkata
for spectral measurements. Financial assistances from CSIR
[Grant no. 02(0110)/12/EMR-II] New Delhi and UGC are also
gratefully acknowledged. The authors are grateful to Prof. Vivek
K. Gupta, Post-Graduate Department of Physics, University of
Jammu, Jammu Tawi – 180 006, India for collecting the X-ray
data.
29.14; TOF-MS: 471.1157 [M
19H21ClN6O5: C 50.84, H 4.72, N 18.72; found: C 50.81, H 4.69,
N 18.75.
+
Na]+; anal. calcd for
C
5,50-((4-Hydroxyphenyl)methylene)bis(6-amino-1,3-dimethyl-
pyrimidine-2,4(1H,3H)-dione) (3r). Yellow solid, yield 82%; mp
232–234 ꢀC; IR (nmax/cmꢁ1, KBr): ¼ 3420, 3171, 2964, 1682, 1599,
1499, 1379, 1258, 1161, 1055, 960, 775; 1H NMR (400 MHz,
DMSO-d6): dH 9.06 (s, 1H, –OH), 7.37 (br s, 4H, 2ꢂ –NH2), 6.85
(d, 2H, J ¼ 8.0 Hz, ArH), 6.59 (d, 2H, J ¼ 8.4 Hz, ArH), 5.48 (s, 1H,
–CH–), 3.32 (s, 6H, 2ꢂ NCH3), 3.13 (s, 6H, 2ꢂ NCH3); 13C NMR
(100 MHz, DMSO-d6): d 163.47, 163.21, 161.30, 156.79, 155.04,
150.89 (2C), 138.65, 129.70, 127.82 (2C), 115.91, 114.96 (2C),
87.12, 86.13, 34.89 (2C), 30.34 (2C), 28.40; TOF-MS: 437.1544
[M + Na]+; anal. calcd for C19H22N6O5: C 55.07, H 5.35, N 20.28;
found: C 55.05, H 5.37, N 20.22.
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This journal is © The Royal Society of Chemistry 2015
RSC Adv., 2015, 5, 39263–39269 | 39269