An efficient stereo-controlled synthesis of bis-pyrimido-[4,5-d]-pyrimidine derivatives via aza-Diels-Alder methodology and their preliminary bioactivity

Article abstract of DOI:10.1039/c3ra22089c

The one-pot synthesis of novel fused bis-pyrimido-[4,5-d]pyrimidine derivatives by a three-component reaction of 6-[(dimethylamino)methylene]1,3- dimethylaminouracil, terephthalaldehyde and amino derivatives has been depicted. The structures of the compounds were established by studying various spectroscopic methods and single-crystal X-ray crystallography. The long range W-coupling constant in ¹H-NMR spectra is an infrequent example, where our synthesized novel compounds show such a distinctive constant. The synthetic strategy provides an efficient way to synthesise bis-pyrimidine-fused heterocycles that can be explored for further potential pharmaceutical or biological activities.

Full text of DOI:10.1039/c3ra22089c

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An efficient stereo-controlled synthesis of bis-pyrimido-
[4,5-d]-pyrimidine derivatives via aza-Diels–Alder
methodology and their preliminary bioactivity3{
Cite this: RSC Advances, 2013, 3,
3407
Subrata Das,*ab Ashim Jyoti Thakur,*b Tapas Medhic and Babulal Dasd
The one-pot synthesis of novel fused bis-pyrimido-[4,5-d]pyrimidine derivatives by a three-component
reaction of 6-[(dimethylamino)methylene]1,3-dimethylaminouracil, terephthalaldehyde and amino deri-
vatives has been depicted. The structures of the compounds were established by studying various
spectroscopic methods and single-crystal X-ray crystallography. The long range W-coupling constant in 1H-
NMR spectra is an infrequent example, where our synthesized novel compounds show such a distinctive
constant. The synthetic strategy provides an efficient way to synthesise bis-pyrimidine-fused heterocycles
that can be explored for further potential pharmaceutical or biological activities.
Received 9th September 2012,
Accepted 30th October 2012
DOI: 10.1039/c3ra22089c
www.rsc.org/advances
LUMO orbitals for
a number of aza-dienes have been
Introduction
reported.4 One of the reasons for the low reactivity of aza-
dienes is the presence of the nitrogen atom that creates a
p-electron-deficient system and thus lowers the reactivity in
normal HOMOdiene controlled DARs with electron poor
dienophiles.5 It has also been postulated that the dienophilic
nature of the pyrimidine ring is rather limited, and the diene
properties of vinylpyrimidines have not yet been established.
Pyrimidine and fused pyrimidine derivatives are indispen-
sable components of the biopolymers of RNA/DNA and are
well known for their bioactivities. In 1960 Taylor et al. first
reported the synthetic procedure for a series of pyrimido[4,5-
d]pyrimidines as potential diuretic agents starting with
4-amino-5-cyanopyrimidines and 4-aminopyrimidine-5-carbox-
mides.6 Sharma et al. reported the synthesis of pyrimido[4,5-
d]pyrimidines and studied their bioactivity.7 Saravanan et al.
also reported that pyrimido[4,5-d]pyrimidine derivatives act as
nucleoside transport inhibitors (NTI) with improved in vivo
pharmacokinetic properties and reduced a1-acid glycoprotein
(AGP) binding relative to dipyridamole.8 Recently pyri-
mido[4,5-d]pyrimidine derivatives have exposed good potenti-
ality against in vitro HBV DNA replication inhibition and as
nucleoside transport inhibitors.9 We have previously shown 6-
The Diels–Alder reaction (DAR) is one of the most well studied
methods for the synthesis of cycloaddition adducts in organic
transformation. The corresponding aza version of the DAR, i.e.
aza-Diels–Alder reaction (aza-DAR) is a powerful methodology
for the construction of 100% economically nitrogen-contain-
ing six-member ring compounds in
a single step and
constitute a broad spectrum of natural products, alkaloids,
pharmaceutically and biologically active compounds and
polymeric materials.1 The regio- and stereo-selectivities of
the products via the DAR methodology are well known under
mild reaction conditions.2 Not only have the chemical
synthesis and the total synthesis of bio-active compounds
been reported via aza-DAR, but the biosynthesis of many
natural products has also been reported.3
The existing compelling evidence of aza-dienes having low
reactivity in normal DARs has been based on calculated
energies of activation (Ea). Experimental ionization potentials,
electron affinities and theoretical energies of the HOMO and
aDepartment of Chemistry, National Institute of Technology-Agartala, Tripura, India.
E-mail: subrataorg@gmail.com; Tel: 919612176571
bDepartment of Chemical Sciences, Tezpur University, Assam, India
cDepartment of Molecular Biology and Biotechnology, Tezpur University, Assam,
India
[(dimethylamino)methylene]-1,3-dimethylaminouracil
(ami-
dine) as an interesting reagent for novel fused pyrimidine
derivatives.10 Here, we have described aza-DARs of one pot
three component reactions of terephthalaldehyde (1), amines
(2) and amidine (3), which lead to the production of novel bis-
pyrimido[4,5-d]pyrimidine derivatives (Scheme 1). To the best
of our knowledge, there are no reports in the literature for the
synthesis of such bis-pyrimido-[4,5-d]pyrimidine derivatives
via our developed methodology and no studies of their
bioactivity.
dIndian Institute of Technology-Guwahati, Department of Chemistry, Guwahati-
781039, Assam, India
Crystallographic data (excluding structure factors) for 4b have been deposited
3
with the Cambridge Crystallographic Data Centre. CCDC reference number
878092. For crystallographic data in CIF or other electronic format see DOI:
10.1039/c3ra22089c
{ Crystal data for 4b (C36H35Cl2N10O5): Mr = 758.64, orthorhombic, Pnma, a =
16.0317(17) Å, b = 22.181(2) Å, c = 10.2433(13) Å, V = 3642.5(7) Å3, T = 296(2)K, Z =
4, Rint = 0.1134, reflection collected/unique = 35187/3857, 2hmax = 53.0u, GOF =
1.070, R1[I > 2s(I)] = 0.0909 and wR2 = 0.2956 (for all data).
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Table 2 Synthesis of bis-pyrimido[4,5-d]pyrimidine derivatives (4a–k)a
Entry
R
Time/h
m.p. (uC)
Yield (%)
a
b
c
d
e
f
g
h
i
C6H5
11
10
12
11
11
12
12
12
24
24
24
360
365
276
293
295
287
229
287
—
91
97
73
81
78
83
81
84
21
17
25
p-Cl–C6H4
p-OCH3–C6H4
p-CH3–C6H4
o-CH3–C6H4
p-NO2–C6H4
o-NO2–C6H4
m-NO2–C6H4
CH3
j
k
CH3–(CH2)3
C6H4–CH2
—
—
a
Isolated yield.
Scheme 1 Synthesis of bis-pyrimido[4,5-d]pyrimidine derivatives (4a–k).
Based on this optimised reaction strategy we continued our
generalization with a series of aromatic and aliphatic amines
(entries 4a–k, Table 2) (Scheme 1). Aromatic amines led to the
formation of more stereo-controlled bis-pyrimido-[4,5-d]pyr-
imidine derivatives with high yields as compared to aliphatic
ones. The results are summarized in Table 2. Here, the
reaction proceeds in two steps, first presumably via the
formation of condensation reaction of (1) and (2a) to form
bis-imine (A) (Scheme 1). Second step is the formation of
hetero-Diels–Alder product of (A) with (3) to form bis-
pyrimido[4,5-d]pyrimidine (4a).
Amine moieties having chloro-substituents lead to the
production of good yields followed by unsubstituted aromatic
amines. In the case of aliphatic amines we observed very poor
yields (entries i–k, Table 2). In our second approach we did not
observe any spectacular results as compared to the first
approach. Furthermore, in the second approach the reaction
proceeded in the presence of hygroscopic catalyst followed by
complex reaction conditions (Scheme 2). Scheme 1 is more
economical and sympathetic than Scheme 2 in context with
synthetic inspection.
Results and discussion
Chemical synthesis
Two major approaches were applied to the synthesis of the
proposed pyrimidine compounds. The first approach
employed the corresponding bis-pyrimido-[4,5-d]pyrimidine
derivatives via the one-pot multi-component reaction of
amidine (3), terephthalaldehyde (1) and aniline (2a) under
reflux in toluene without using any catalyst. The second one
involved the construction of a one-pot multi-component
reaction using In(OTf)3 as catalyst in chloroform for a
successive three step reaction. Initially, we intended to adopt
the direct DAR through reflux in nitrobenzene aromatization.
However, it was very complex to get bis-pyrimido-[4,5-
d]pyrimidine up to a good quantity (see Table 1). In those
cases some product also got burnt at the time of removing the
nitrobenzene from the reaction mixture. To increase the
reaction yield with more trustworthy reaction conditions, we
used various reaction directions (Table 1). In our first
approach we found that toluene is a good solvent for the
synthesis of bis-pyrimido-[4,5-d]pyrimidine (see entry 10,
Table 1).
To justify the reaction procedure we also tried a two step
reaction for the synthesis of bis-pyrimido[4,5-d]pyrimidine
Table 1 Optimization of the reaction conditions for the model reactions
between (1), (2a) and (3)
Entry
Reaction Conditions
Time/h
Yield (%)a
1
2
3
4
5
6
7
8
9
Water, reflux
12
12
12
12
12
12
12
12
12
12
No product
No product
No product
Trace
Water, reflux, 15 mol% p-TSA
H2O, SDSb, rt, 10 mol% p-TSA
H2O, SDS, reflux, 10 mol% p-TSA
CH3CN, reflux
EtOH, reflux
MeOH, reflux
DMF, reflux
PhNO2, reflux
Toluene, reflux
Trace
No product
No product
20
44
91
10
a
Yield (%) is referred to isolated yields and calculated from mol of
b
product/mol of initial substrate 6100. SDS = Sodium dodecyl
sulphate.
Scheme 2 Synthesis of bis-pyrimido[4,5-d]pyrimidine derivative (4a).
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Scheme 3 Synthesis of bis-pyrimido[4,5-d]pyrimidine derivative (4a).
(4a). For that we first synthesized the bis-imine (A, R = Ph), by
the reaction of (1) and (2a). Then in the second step we carried
out the reaction of the bis-imine (A) with the amidine (3)
(Scheme 3) via both the reaction approaches. We achieved the
same product (4a) without observing any customary results.
In the 1H NMR spectrum of 4a (R = Ph), the peaks at d = 3.25
(6H) and 3.31 (6H) ppm are due to the six N-methyl groups, the
peak at d = 5.99 ppm is due to the CH proton, the peaks within
d = 7.03–7.06 and d = 7.27–7.38 ppm are due to the five
aromatic protons and the peak at d = 7.78 ppm is due to the
imine proton. Similarly, (4b) was obtained in 97% yield within
10 h. In the 1H NMR spectrum of 4b (R = ClPh), the peaks at d
3.27, 3.54 and 5.96 (J = 10.8 Hz, CH), 6.98–7.00, 7.28–7.37 and
Fig. 2 The ORTEP diagram of compound 4b (thermal ellipsoids are drawn with
30% probability). The letter "a" in the atom labels indicates that these atoms are
at equivalent positions (x, 1/22y, z).
The value of the W-coupling constant is the exhibited
difference due to the substituent proximity in relation to the
W-positioned hydrogen atoms. If the substituents are on the
same side of the ring as the W-positioned hydrogen atoms, low
W-coupling constants are observed, while substituents on the
opposite side of the W-positioned hydrogen atoms seem to
permit higher coupling constants.11 The structure was further
confirmed through single crystal X-ray analysis and the long
range W-coupling constant was also supported by X-ray
analysis. Suitable crystals were obtained by the slow evapora-
tion of 4b from DMF solution. The ORTEP diagram of the
compound 4b is shown in Fig. 2 and it was found that the
compound had mirror symmetry. From the ORTEP diagram
we can suggest that compound 4b may be in the cis form due
to same priority groups (in this case H and the lone pair on
nitrogen) being on the same side across the CLN bond. This cis
conformation may be further supported by NMR data, i.e. in
the NMR spectrum we saw a low coupling constant value. This
cis form may also be stabilised by the DMF solvent molecule.
In the lattice the carbonyl group of the compound exhibits a
7.73 (J
= 7.8 Hz) ppm indicate the formation of the
corresponding chloro-subtituted bis-pyrimido[4,5-d]pyrimi-
dine derivative (Fig. 1).
…
large number of C–H O interactions with the adjacent
molecule. The CLO group of DMF also interacts with the
chloro-benzene ring of the compound via similar weak
interactions, further contributing to the stability of the
molecule.
A plausible mechanism for the reaction is described in the
Fig. 3. Mechanistically, in the three-component reaction, the
bis-imine (A) is first formed by the reaction between the
dialdehyde (1) and amine (2a). Bis-imine (A) acts as a
dienophlie which reacts with amidine (3) diene to form the
product (4a) via the normal hetero-Diels–Alder reaction.
Antimicrobial activity
All the newly synthesized bis-pyrimido[4,5-d]pyrimidine deri-
vatives were assessed for their in vitro antibacterial properties
against both gram positive and gram negative bacteria viz.
Fig. 1 The 1H NMR spectrum of 4b, which shows the long range W-coupling
constant.
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Table 4 Zone of inhibition of the bis-pyrimido[4,5-d]pyrimidine derivatives (4a–
h)
Zone of Inhibition/mm
Entry
E. coli
P. diminuta
4a
4b
4c
4d
4e
4f
11
13
12
11
11
11
12
11
10
12
11
11
11
11
13
11
11
11
13
12
13
13
13
11
11
11
13
11
13
12
13
11
Fig. 3 The plausible reaction mechanism.
4g
4h
Staphylococcus aureus (ATCC 11632), Bacillus subtilis (ATCC
11774), Escherichia coli (ATCC 13607), and P. diminuta (MTCC
7814) and antifungal activity against A. niger (MTCC 284) and
Candida albicans (MTCC 227).
solidified nutrient agar (NA) and sabouraud dextrose agar
(SDA) plates, respectively, with the help of a sterile cork borer.
Concentrations of 0.125 mg mL21, 0.25 mg mL21, 0.5 mg
mL21, 1.0 mg mL21 and 2.0 mg mL21 of the synthesized
compound dissolved in sterilized DMSO were introduced into
each of the wells. Due to the poor solubility of bis-
pyrimido[4,5-d]pyrimidine derivatives in common organic
solvents or water, all the compounds were dissolved and
tested for corresponding antimicrobial activities in 10% DMSO
(v/v) aqueous solution as DMSO solvent is highly miscible with
water, highly polar and stable with exceptional solvent
properties.15 It was also found from literature that 10%
DMSO (v/v) has been used for antimicrobial and other
biological activities.16 As in our previous study of the
antimicrobial activities of bis-pyrimido[4,5-d]pyrimidine deri-
vatives we first screened the percentage of DMSO (ranging
from 1% to 15%, v/v) that is tolerated by cells or not. In the
presence of 10% DMSO (v/v) both the gram positive and gram
negative bacteria had no detectable effect on bacterial growth.
Again it was also noticeable that different organisms
responded differently to the same concentration of a given
solvent.17 Here, our tested bacteria and fungi were comfortable
with 10% DMSO (v/v) and it showed no detectable effect on
growth. Compounds at concentrations of 125 mg–2000 mg
mL21 were prepared in 10% DMSO (v/v). Streptomycin (1 mg
ml21) and sterilized 10% DMSO (v/v) without the synthesized
compound were taken as a positive and negative control,
respectively, and for fungi clotrimazole was used to serve as a
positive control. Plates with discs containing respective 10%
DMSO (v/v) solvents also served as controls. It was found that
Nutrient agar and sabouraud dextrose agar were employed
for bacterial and fungal growth, respectively. An organized
form of the data is illustrated in Table 3, Table 4 and Table 5
which reveals that the antibacterial behaviour of the tested
compounds are highly significant and pronounced compared
to their antifungal behaviour. Gram negative bacteria were
found to be sensitive to the bis-pyrimido[4,5-d]pyrimidine
derivatives. On the other hand, bis-pyrimido[4,5-d]pyrimidine
derivatives showed the least growth inhibition against fungi.
Furthermore, an elaborate examination of the screening
results reveals that all the bis-pyrimido[4,5-d]pyrimidine
derivatives equally showed good anti-bacterial properties, only
p-Cl substituted bis-pyrimido[4,5-d]pyrimidine derivatives
(MIC 12.5 mg) show good activity compared to the other bis-
pyrimido[4,5-d]pyrimidine derivatives (MIC 25–50 mg).
The agar well diffusion technique was used in the present
investigation, following the procedure described by Boakye-
Yiadom,12 Banso and Adeyemo13 and Radhika, et al.14 200 ml of
overnight grown culture (inoculums size was 107–108 cells
mL21 as per McFarland standard) of the test bacterial strains
were seeded on the surface of the Muller Hinton agar while the
fungal strains (0.5–2.5 6 106 mL21) were seeded on the
sabouraud dextrose agar (SDA) medium, using a sterile glass
pipette and spread over the medium using a sterile glass
spreader. A total of five wells, 6 mm each were made on the
Table 3 Antibacterial activity tests of the bis-pyrimido[4,5-d]pyrimidine deriva-
tives (4a–h)a
Entry
Gram Negative Bacteria
Gram Positive Bacteria
Fungi
Table 5 MIC values of the pyrimido[4,5-d]pyrimidine derivatives (4a–h)
EC
PD
BS
SA
CA AN
MIC (mg ml21
)
4a
4b
4c
4d
4e
4f
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Entry
E. coli
P. diminuta
4a
4b
4c
4d
4e
4f
0.5
0.25
0.25
0.25
0.25
0.25
0.5
0.125
0.25
0.25
0.25
0.25
0.125
0.25
4g
4h
a
EC = Escherichia coli; PD = P. diminuta; BS = Bacillus subtilis; SA =
Staphylococcus aureus; CA = Candida albicans; AN = A. niger.
4g
4h
0.25
0.5
3410 | RSC Adv., 2013, 3, 3407–3413
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laldehyde (1) (134 mg, 0.5 mmol) and aniline (2a) (0.091 ml, 1
mmol) was placed in a 50 ml round bottom flask, then y15 ml
toluene was added and it was allowed to reflux overnight. After
completion of the reaction the product precipitated out from
the reaction mixture which was then washed with ethyl acetate
to remove any unreacted reactant and other byproducts. The
pure product was dried at high vacuum using a pump and
solubilised in DMF, re-crystallized and we got the bright yellow
pure product (4a) in 91% yield; m.p. 360 uC.
DMSO showed no effect against the microorganisms under
test. In the case of bacteria, the plates were incubated at 37 ¡
2 uC for 24 h while for fungal cultures; the plates were kept at
27 ¡ 2 uC for 48 h. The observed zones of inhibition were
measured using a transparent metric ruler. The experiment
was done thrice and the mean values were determined.
The minimum inhibitory concentration (MIC) of the
synthesized compounds was determined by the micro dilution
method and compared to broad-spectrum antibiotics. MIC is
defined as the lowest concentration of a compound that
inhibits visible growth of the test organism. All the synthesized
compounds exhibited remarkable in vitro antibacterial activity
against the tested bacteria only and were less significant
towards fungal strains compared to the reference antibiotics.
The same reaction procedure was followed for the rest of the
substrates.
For Scheme 2. 6-[(Dimethylamino)methylene]1,3-dimethyl-
aminouracil (3) (209 mg, 1 mmol), terephthalaldehyde (1) (134
mg, 0.5 mmol) and aniline (2a) (0.091 ml, 1 mmol) was mixed
in dry chloroform (20 mL) in a 50 mL round-bottomed flask
and was stirred at room temperature for 10 min. The reaction
mixture was cooled to 0 uC using an ice bath, then In(OTf)3 (5.6
mg, 10% of 1 mmol) was added with constant stirring.
Gradually, the reaction mixture was allowed to come to room
temperature. Then the reaction mixture was refluxed at 60 uC
with constant stirring and after 6 h we obtained the pure
product (4a) in 91% yield. The product was separated through
TLC, dissolved in distilled DMF and then warmed, filtered,
allowed to cool and the filtrate was evaporated at room
temperature for crystallization.
To improve the solubility of the compounds, the pure
compounds were refluxed in nitrobenzene for 5/6 h.
The same reaction procedure was followed for the rest of the
substrates.
Pure compounds were insoluble in water, sparingly soluble
in common organic solvents and completely soluble in aprotic
polar solvents like DMF, DMSO and DMAc etc.
Conclusions
Diels–Alder methodology (aza-version) has been found to be a
useful and efficient method for the construction of fused
heterocyclic systems like bis-pyrimido[4,5-d]pyrimidine deriva-
tives in good to excellent yields. The scope and generality of this
methodology have been successfully demonstrated by synthe-
sizing a variety of fused pyrimidine derivatives. We believe that
our developed methodologies will open a new vista for the
construction of wide varieties of synthetic/natural/biological
compounds. The prominent advantages of the described report
are the novelty of synthesized compounds, operational simpli-
city, good yields and easy workup procedures without the need
for any further separation techniques (for Scheme 1).
Preliminary antimicrobial activity tests show that bis-pyri-
mido[4,5-d]pyrimidine derivatives are active against gram
negative bacteria and inactive against gram positive bacteria.
5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-2,4-dioxo-
6-phenylpyrimido[4,5-d]-pyrimidin-5-yl)phenyl)-1,3-dimethyl-
6-phenylpyrimido[4,5-d]pyrimidine-2,4-(1H,3H)-dione (4a)
IR (KBr) (nmax/cm21) 3073.78, 2941.61, 1698.17, 1640.16,
1532.89, 1471.29; dH (100 MHz; DMSO-d6) 3.25 (s, 6H,
NCH3), 3.31 (s, 6H, NCH3), 5.99 (d, 2H, J = 10.52 Hz, CH),
7.03–7.06 (m, 4H, arom.), 7.27–7.38 (m, 8H, arom.), 7.78 (d,
2H, J = 7.8 Hz, CHLN); dC (100 MHz; DMSO-d6) 28.2, 29.7, 58.5,
58.7, 91.1, 123.7, 123.8, 127.1, 127.2, 130.1, 130.2, 133.5, 140.1,
141.9, 142.0, 148.9, 152.0, 152.1, 161.1; MS, m/z 614 (M+); Anal.
Calcd (%) for C34H30N8O4: C, 66.44; H, 4.92; N, 18.23. Found C,
66.43; H, 4.96; N, 18.21.
Experimental section
Melting points were determined with Bu¨chi 504 apparatus. IR
spectra were recorded as KBr pellets with a Nicolet (Impact
410) FT-IR spectrophotometer. H and 13C NMR spectra were
1
recorded with a JNM ECS 400 MHz NMR spectrophotometer
(JEOL) using tetramethylsilane (TMS) as the internal standard.
X-Ray intensity data were collected with a Bruker SMART APEX
CCD area-detector diffractometer with Mo-Ka radiation (l =
0.71073 Å). The structures were solved by SHELX97 and refined
by full-matrix least-squares on F2 (SHELX97). Reactions were
monitored by thin-layer chromatography using aluminium
sheets with silica gel 60F254 (Merck). Elemental analyses were
carried out with a Perkin-Elmer CHN analyzer (2400 series II).
Mass spectra were recorded with a Waters Q-TOF Premier and
Aquity UPLC spectrometer. All the chemicals were used as
received.
6-(4-chlorophenyl)-5-(4-(6-(4-chlorophenyl)-1,2,3,4,5,6-
hexahydro-1,3-dimethyl-2,4-dioxopyrimido[4,5-d]pyrimidin-5-
yl)phenyl)-5,6-dihydro-1,3-dimethylpyrimido-[4,5-d]-
pyrimidine-2,4(1H,3H)-dione (4b)
IR (KBr) (nmax/cm21) 3071.98, 2943.13, 1698.27, 1641.06,
1533.19, 1471.27; dH (100 MHz; DMSO-d6) 3.27 (s, 6H,
NCH3), 3.54 (s, 6H, NCH3), 5.96 (d, 2H, J = 10.8 Hz, CH),
6.98–7.00 (m, 4H, arom.), 7.28–7.37 (m, 8H, arom.), 7.73 (d,
2H, J = 7.8 Hz, CHLN); dC (100 MHz; DMSO-d6) 28.7, 29.9, 58.4,
58.6, 91.0, 122.9, 123.4, 126.9, 127.0, 129.7, 129.8, 133.6, 140.1,
141.7, 142.2, 148.7, 152.7, 153.1, 161.7; MS, m/z 682 (M+); Anal.
Calcd (%) for C34H28Cl2N8O4: C, 59.74; H, 4.13; N, 16.39.
Found C, 59.71; H, 4.21; N, 16.36.
Typical reaction procedures for the synthesis of pyrimido[4,5-
d]pyrimidine derivative 4a
For Scheme 1. A mixture of 6-[(dimethylamino)methy-
lene]1,3-dimethylaminouracil (3) (209 mg, 1 mmol), terephtha-
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5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-6-(4-methoxyphenyl)-
1,3-dimethyl-2,4-dioxo-pyrimido[4,5-d]pyrimidin-5-yl)phenyl)-
6-(4-methoxyphenyl)-1,3-dimethyl-pyrimido[4,5-d]pyrimidine-
2,4(1H,3H)-dione (4c)
5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-6-(2-
nitrophenyl)-2,4-dioxo -pyrimido[4,5-d]pyrimidin-5-yl)phenyl)-
1,3-dimethyl-6-(2-nitrophenyl)pyrimido[4,5-d]-pyrimidine-
2,4(1H,3H)-dione (4g)
IR (KBr) (nmax/cm21) 3073.56, 2941.43, 1698.21, 1641.17,
1532.78, 1472.31; dH (100 MHz; DMSO-d6) 3.29 (s, 6H,
NCH3), 3.37 (s, 6H, NCH3), 5.86 (d, 2H, J = 9.86 Hz, CH),
7.15–7.52 (m, 4H, arom.), 7.70–7.74 (m, 8H, arom.), 8.12 (d,
2H, J = 7.78 Hz, CHLN) ppm; dC (100 MHz; DMSO-d6) 30.4,
33.8, 59.1, 59.4, 87.7, 122.7, 123.7, 126.9, 127.2, 129.1, 130.0,
132.3, 139.7, 140.1, 141.6, 142.7, 148.8, 152.5, 153.1, 162.7; MS,
m/z 704 (M+); Anal. Calcd (%) for C34H28N10O8: C, 57.95; H,
4.01; N, 19.88. Found C, 57.93; H, 4.06; N, 19.87.
IR (KBr) (nmax/cm21) 3072.89, 2941.34, 1697.68, 1641.43,
1532.71, 1470.91; dH (100 MHz; DMSO-d6) 3.36 (s, 6H,
NCH3), 3.39 (s, 6H, NCH3), 3.48 (s, 3H, OCH3), 6.43 (d, 2H, J
= 10.2 Hz, CH), 6.77–7.21 (m, 4H, arom.) 7.68–8.00 (m, 8H,
arom.), 8.10 (d, 2H, J = 7.8 Hz, CHLN); dC (100 MHz; DMSO-d6)
28.8, 29.1, 34.8, 58.0, 58.2, 89.7, 123.1, 123.6, 126.9, 127.1,
129.6, 130.1, 132.8, 140.4, 141.3, 142.2, 149.5, 152.7, 153.1,
163.2; MS, m/z 674 (M+); Anal. Calcd (%) for C36H34N8O6: C,
64.09; H, 5.08; N, 16.61. Found C, 64.07; H, 5.05; N, 16.65.
5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-6-(3-
nitrophenyl)-2,4-dioxo-pyrimido[4,5-d]pyrimidin-5-yl)phenyl)-
1,3-dimethyl-6-(3-nitrophenyl)pyrimido[4,5-d]-pyrimidine-
2,4(1H,3H)-dione (4h)
IR (KBr) (nmax/cm21) 3073.56, 2941.63, 1698.31, 1640.17,
1532.78, 1471.41; dH (100 MHz; DMSO-d6) 3.28 (s, 6H,
NCH3), 3.37 (s, 6H, NCH3), 5.86 (d, 2H, J = 9.4 Hz, CH),
7.10–7.47 (m, 4H, arom.), 7.63–7.74 (m, 8H, arom.), 8.09 (d,
2H, J = 7.78 Hz, CHLN); dC (100 MHz; DMSO-d6) 30.3, 309.8,
59.1, 59.4, 87.9, 122.7, 123.7, 126.9, 127.2, 129.1, 130.0, 132.3,
138.9, 140.1, 141.6, 142.7, 148.8, 152.5, 153.1, 162.7; MS, m/z
704 (M+); Anal. Calcd (%) for C34H28N10O8: C, 57.95; H, 4.01; N,
19.88. Found C, 57.93; H, 4.06; N, 19.87.
5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-2,4-dioxo-
6-p-tolylpyrimido[4,5-d]pyrimidin-5-yl)phenyl)-1,3-dimethyl-6-
p-tolylpyrimido-[4,5-d]pyrimidine-2,4 -(1H,3H)-dione (4d)
IR (KBr) (nmax/cm21) 3073.76, 2942.14, 1698.43, 1641.28,
1532.73, 1471.45; dH (100 MHz; DMSO-d6) 2.06 (s, 3H, CH3),
3.38 (s, 6H, NCH3), 3.35 (s, 6H, NCH3), 6.42 (d, 2H, J = 9.87 Hz,
CH), 6.75–7.13 (m, 4H, arom.) 7.63–8.00 (m, 8H, arom.), 8.07
(d, 2H, J = 7.24 Hz, CHLN); dC (100 MHz; DMSO-d6) 21.6, 28.9,
29.3, 57.9, 58.1, 89.8, 122.7, 123.1, 126.9, 127.2, 129.6, 129.9,
132.8, 140.3, 141.2, 142.1, 149.1, 152.7, 153.1, 162.5; MS, m/z
642 (M+); Anal. Calcd (%) for C36H34N8O4: C, 67.28; H, 5.33; N,
17.43. Found C, 67.31; H, 5.36; N, 17.41.
5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-2,4-dioxo-
6-o-tolylpyrimido[4,5-d]pyrimidin-5-yl)phenyl)-1,3-dimethyl-6-
o-tolylpyrimido-[4,5-d]pyrimidine-2,4 -(1H,3H)-dione (4e)
Acknowledgements
IR (KBr) (nmax/cm21) 3073.76, 2942.14, 1698.43, 1641.28,
1532.73, 1471.45; dH (100 MHz; DMSO-d6) 2.06 (s, 3H, CH3),
3.31 (s, 6H, NCH3), 3.34 (s, 6H, NCH3), 6.39 (d, 2H, J = 10.12
Hz, CH), 6.95–7.20 (m, 4H, arom.) 7.78–8.03 (m, 8H, arom.),
8.07 (d, 2H, J = 8.54 Hz, CHLN); dC (100 MHz; DMSO-d6) 21.5,
28.4, 28.9, 57.6, 58.1, 89.8, 122.8, 123.3, 126.7, 127.2, 129.6,
129.9, 132.8, 139.7, 140.2, 141.2, 142.1, 149.0, 152.5, 154.1,
162.3; MS, m/z 642 (M+); Anal. Calcd (%) for C36H34N8O4: C,
67.28; H, 5.33; N, 17.43. Found C, 67.31; H, 5.36; N, 17.41.
We thank S. J. Kalita, P. Bharali and B. K. Konwer for their
assistance with modifying the manuscript and bioactivities
studies, respectively. This work was supported in part by
grants from the DST (Grant number SR/FTP/CS-58/2005), Govt.
of India.
Notes and references
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5,6-dihydro-5-(4-(1,2,3,4,5,6-hexahydro-1,3-dimethyl-6-(4-
nitrophenyl)-2,4-dioxo-pyrimido[4,5-d]pyrimidin-5-yl)phenyl)-
1,3-dimethyl-6-(4-nitrophenyl)pyrimido[4,5-d]-pyrimidine-
2,4(1H,3H)-dione (4f)
IR (KBr) (nmax/cm21) 3073.56, 2941.63, 1696.78, 1640.17,
1532.98; dH (100 MHz; DMSO-d6) 3.31 (s, 6H, NCH3), 3.38 (s,
6H, NCH3), 5.88 (d, 2H, J = 9.72 Hz, CH), 7.10–7.47 (m, 4H,
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57.94; H, 4.03; N, 19.87.
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3412 | RSC Adv., 2013, 3, 3407–3413
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