A clean, highly efficient and one-pot green synthesis of aryl/alkyl/heteroaryl-substituted bis(6-amino-1,3-dimethyluracil-5-yl)methanes in water

Article abstract of DOI:10.1002/ejoc.201001581

A highly efficient green synthesis of aryl/alkyl/heteroaryl-substituted bis(6-amino-1,3-dimethyluracil-5-yl)methanes by the condensation of 6-amino-1,3-dimethyluracil with aldehydes (aromatic, aliphatic and heterocyclic) in water at room temperature is de

Full text of DOI:10.1002/ejoc.201001581

FULL PAPER
DOI: 10.1002/ejoc.201001581
A Clean, Highly Efficient and One-Pot Green Synthesis of Aryl/Alkyl/
Heteroaryl-Substituted Bis(6-amino-1,3-dimethyluracil-5-yl)methanes in Water
Subrata Das[a] and Ashim Jyoti Thakur*[a]
Keywords: Nitrogen heterocycles / Green chemistry / Heterocycles / Water chemistry
A highly efficient green synthesis of aryl/alkyl/heteroaryl-
temperature is described. No dehydrating agent, heat, cata-
substituted bis(6-amino-1,3-dimethyluracil-5-yl)methanes by lyst, surfactant or additive was used. The structures of the
the condensation of 6-amino-1,3-dimethyluracil with alde-
hydes (aromatic, aliphatic and heterocyclic) in water at room
compounds were established by spectroscopic methods and
single-crystal X-ray crystallography.
low’s seminal observation that Diels–Alder reactions could
be greatly accelerated by using a water suspension rather
than solution instead of organic solvents established the im-
portance of water in organic synthesis.[9] Since then, this
area of research has burgeoned. On the other hand, organic
solvents contribute the lion’s part to the pollution problem
in practical chemistry,[10] both in the laboratory as well as
in industry. Hence, the search for efficient synthetic meth-
odologies for organic reactions without the use of organic
solvents is an important challenge in reducing the amount
of waste generated.[11] An ideal organic reaction demands
that it would proceed neat, that is, with no solvent, or in an
environmentally benign solvent such as water.
Uracil, a nucleobase of the pyrimidine family, is one of
the major motifs present in the biopolymer RNA[12] and it
plays several roles in our life cycle.[13] The versatility of the
uracil scaffold and its derivatives, as exhibited by their wide
range of biological activities, has brought chemists[14] and
biologists together.[15] Several patents also report promising
pharmaceutical agents of uracil origin for the treatment of
cancer and viral diseases.[16] To name but a few, uracil
derivatives are also useful as bronchodilators and anti-
cancer agents,[17] antiallergic compounds,[17,18a] antiviral
agents,[18b] antihypertensive agents[19] and adenosine recep-
tor antagonists.[20] In addition, 5-substituted uracils and
their nucleosides are widely used in the chemotherapy of
cancer.[21] Pyrimidine derivatives have also been used in co-
ordination chemistry.[22] In view of the biological signifi-
cance of pyrimidine compounds, we have been focussing on
the design and synthesis of such pyrimidine derivatives.[23]
Introduction
The general belief is that life started from organic com-
pounds in an aqueous environment. Szent-Gyorgyi rightly
dubbed water the “matrix of life”[1] and it is regarded as a
universal solvent. Mimicking nature and bearing in mind
environmentally friendly protocols, the use of water as a
remarkable solvent with a difference in organic synthesis
has received considerable attention in recent times.[2] The
reason behind this is that water is the solvent of choice from
not only an ecological but also from an economic point of
view. Water is cheap, safe, natural, non-flammable, abun-
dant, available and environmentally benign, that is, it is a
green solvent[3] associated with easy reaction work-up.
Compared with common organic solvents, the unique and
unusual physical (low viscosity, high specific heat, high sur-
face tension, high dielectric constant, large cohesive energy
density etc.) and chemical properties (ability to form hydro-
gen bonds, its amphoteric nature etc.) of liquid water help
to increase the reactivity and selectivity of chemical reac-
tions.[4] Moreover, hydrophobic interactions are also re-
sponsible for reactivity. In spite of these potential advan-
tages, water has not found use as a common organic solvent
because most organic compounds are insoluble in water ac-
cording to the assumption “corpora non agunt nisi solute”
(substances do not interact unless dissolved). Regardless of
this, however, there are many examples of aqueous media
reactions,[5] water used as a co-solvent or on-water[6] reac-
tions performed without dissolving the organic compounds
(coined as the “on-water-effect”). Efforts have been made
to dissolve organic compounds in water by adding additives
like surfactants[7] and applying heat.[8] Rideout and Bres-
Results and Discussion
[a] Department of Chemical Sciences, Tezpur University,
Napaam, Tezpur 784028, Assam, India
Thus, bearing in mind the importance of water and the
uracil moiety together, herein we report a clean, highly ef-
ficient and one-pot green method for the synthesis of bis-
uracil compounds 3 by the reaction of 6-amino-1,3-dimeth-
Fax: +91-3712-267005/6
E-mail: ashim@tezu.ernet.in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001581.
Eur. J. Org. Chem. 2011, 2301–2308
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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S. Das, A. J. Thakur
FULL PAPER
yluracil (1; at the 5-position) and aldehydes 2 in water at required. Our method eliminates all of the above-mentioned
room temperature without using any catalyst, surfactant, drawbacks with an added advantage.
additive, dehydrating agent, heat or organic solvent
(Scheme 1).
Bis-uracil and their analogues have also been isolated
from marine sea hare Dolabella auricularia.[30] Semenov and
co-workers have been actively working on the synthesis of
N-substituted bis-uracil analogues and the bioactivities of
the synthesized compounds.[31]
In an attempt to synthesize imines 4 from 6-amino-1,3-
dimethyluracil (1) and benzaldehyde 2 (R = Ph) (Scheme 2)
we tested several reaction conditions, both conventional
and non-conventional, using a catalyst or in the absence of
catalyst and in the presence or absence of solvent. However,
all the attempts were in vain and we observed the following
interesting results.
Scheme 1. Synthesis of bis-uracil derivatives 3.
In 1986, Lam and Pridgen first reported the reaction of
unsubstituted uracil with aromatic aldehydes in aqueous
mineral acids (e.g., concd. HCl, HBr, HI or H2SO4) at re-
flux.[24] Depending on the nature of substituents on the al-
dehydes, they obtained a mixture of (hydroxymethyl)uracil
and bis-uracil adducts. The condensation reaction of substi-
tuted 6-aminouracils and aromatic aldehydes in ethanol at
reflux or under microwave irradiation wetted by DMSO af-
forded bis-uracil compounds.[25] However, in both the cases,
the reaction failed with aliphatic and heteroaromatic alde-
hydes. Another report presented the synthesis of bis-uracil
compounds from aromatic aldehydes only in methanol and
acetic acid.[26] Hlavác and co-workers in 2007 further ex-
plored the reaction of unsubstituted uracil with 4-nitro-
benzaldehyde and obtained 5-[chloro(4-nitrophenyl)-
methyl]uracil at reflux in aqueous mineral acids and contin-
ued the generalization for the synthesis of 5-[alkoxy(4-ni-
trophenyl)methyl]uracils from 5-[chloro(4-nitrophenyl)-
methyl]uracil. They also studied the anticancer activity of
the synthesized compounds.[27] Bazgir and co-workers in
2007 reported the formation of fused pyrimidine derivatives
via bis-uracil as intermediate in a three-component reaction
of 6-amino-1,3-dimethyluracil, aldehydes and urea cata-
lysed by acetic acid under microwave irradiation.[28] Again,
this method is limited to aromatic aldehydes only. During
the preparation of this manuscript, an interesting report
from Shi et al.[29] showed that the three-component reaction
of aromatic aldehyde, 6-aminopyrimidine-2,4-dione and
Meldrum’s acid in water in the presence of triethylbenz-
ylammonium chloride (TEBAC) at 90 °C for 18–32 h
led to the formation of 5-benzylidenepyrimidine-2,4,6-
Scheme 2. Synthesis of imine 4 or alkene 5.
As a model reaction, when we simply stirred 6-amino-
1,3-dimethyluracil (1) and benzaldehyde (2a; R = Ph) in
water at room temperature, we ended up with the formation
of 5,5Ј-phenylmethylenebis(1,3-dimethyl-6-aminopyrimid-
ine-2,4-dione) (3a) within 1 h in 95% yield (Scheme 1). The
reaction was monitored by TLC. The reaction was very
clean providing only one product, that is, 3a. We did not
observe the formation of product 4 nor the other possible
product 5 (Scheme 2). As the reaction progressed, we ob-
served that the product started to precipitate from the aque-
ous solution and simple filtration afforded the product. The
1
structure was confirmed by IR, H and 13C NMR spec-
troscopy, mass spectrometry and elemental analyses.
1
The H NMR peaks at δ = 3.27 (3 H), 3.34 (3 H) and
3.44 (6 H) ppm are due to the four N-methyl groups, the
peak at δ = 5.79 ppm is due to the ϾCH proton, the broad
singlet peaks at δ = 6.48 and 6.96 ppm are due to the two
–NH2 protons and the peaks at δ = 7.14–7.25 ppm are due
to five aromatic protons. The two –NH2 groups were con-
firmed by shaking with D2O, that is, the –NH2 peak disap-
peared from the 1H NMR spectrum upon shaking with
D2O. The structure was further confirmed by single-crystal
X-ray analysis. Suitable crystals were obtained by slow
evaporation from ethanol solution.
Encouraged by this result, to study the scope and limita-
(1H,3H,5H)-trione and 5,5Ј-(arylmethylene)bis[6-amino- tions of the reaction further, we extended the reaction to
pyrimidine-2,4(1H,3H)-dione]. However, none of these re- other differently substituted aromatic, aliphatic and hetero-
ported methods are general covering all types of aldehydes: cyclic aldehydes and ketones (2a–r) under the same opti-
aliphatic, aromatic and heterocyclic. Moreover, the use of mized reaction conditions. The results are summarized in
mineral acid, acetic acid, additives, microwave irradiation Table 1 (entries a–r). All the aldehydes (entries a–o, Table 1)
or reflux conditions in common organic solvents are neces- reacted with equal ease within short times to furnish the
sary for the synthesis of such substituted or unsubstituted bis-uracils 3a–o in good-to-excellent yields (73–99%) and
bis-uracil adducts. Thus, a general and “green” method is with no side-products.
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Eur. J. Org. Chem. 2011, 2301–2308

Synthesis of Bis(6-amino-1,3-dimethyluracilyl)methanes
Table 1. Synthesis of bis-uracil derivatives 3a–o.
Carbonyl compound 2
Time [h] M.p. [°C] Yield of 3 [%][a]
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
C6H5CHO
1
4
3
0.25
7
7
0.25
10
5
1
6
1
3
3
3
48
48
48
296–299
265–269
273–275
268–270
245–248
247–249
276–279
228–229
224–225
246–250
309–312
328–334
253–256
232–233
159–162
–
95
93
91
99
75
73
99
73
82
99
87
91
92
93
C6H5CH=CHCHO
p-MeOC6H4CHO
p-ClC6H4CHO
p-HOC6H4CHO
o-HOC6H4CHO
p-MeC6H4CHO
p-NO2C6H4CHO
m-NO2C6H4CHO
2-furaldehyde
thiophene-2-carbaldehyde
paraformaldehyde
CH3CHO
CH3(CH2)2CHO
CH3(CH2)3CHO
(CH3)2CO
90
Figure 1. ORTEP diagram of compound 3d.
[b]
–
[b]
[b]
CH3COPh
PhCOPh
–
–
–
–
[a] Isolated yield. [b] No product found.
As illustrated in Table 1 (entries a–o), it is evident that
aromatic, aliphatic and heterocyclic aldehydes are equally
effective for the synthesis of bis-uracil 3. We also obtained
very good yields (Ͼ90%) with aliphatic aldehydes (en-
tries l–o, Table 1). With paraformaldehyde (entry l, Table 1),
6-amino-1,3-dimethyluracil (1) afforded the bis-uracil ad-
duct 3l, 6,6Ј-diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-methylene-
bis[pyrimidine-2,4(1H,3H)-dione] (91% yield). However,
under both acidic and basic conditions, unsubstituted uracil
reacted with paraformaldehyde to produce 5-hydroxymeth-
yluracil, as reported by Kong et al.[32] This is in sharp con-
trast to the report[28] in which the reaction with aliphatic
aldehydes was not mentioned. We performed the reaction
with another three aliphatic aldehydes (entries m–o, Table 1)
with different carbon chain lengths and all the products
were confirmed by NMR (1H and 13C) and FTIR spec-
troscopy, mass spectrometry, elemental analyses and single-
crystal X-ray analysis. ORTEP diagrams for compounds 3d
and 3l are shown in Figures 1 and 2, respectively. From
these ORTEP diagrams, it is clear that both the amino
groups and the two uracil rings are oriented oppositely and
hence they exist in different magnetic environments.
Figure 2. ORTEP diagram of compound 3l.
Figure 3. ORTEP diagram of compound 3j.
Our approach is also equally effective for heterocyclic
compounds. 2-Furaldehyde (entry j) and thiophene-2-carb-
aldehyde (entry k) provided the desired products 3j and 3k
Realizing the difference in reactivity of aldehydes and
in 99 and 87% yields, respectively. 2-Furaldehyde reacted ketones, we also studied the reaction of 6-amino-1,3-di-
within 1 h, but thiophene-2-carbaldehyde required a longer methyluracil (1) with ketones (Scheme 1, Table 1, entries p–
reaction time (6 h). No other products were detected. The r). However, the reaction failed to proceed even after a long
structures of the products were confirmed by NMR (both time (24 h), which shows the chemoselectivity of the reac-
1H and 13C) and FTIR spectroscopy, mass spectrometry, tion, and all the starting materials were recovered. This
elemental analysis and single-crystal X-ray analysis. The chemoselectivity was also established in a competitive ex-
ORTEP diagram of compound 3j is shown in Figure 3.
periment involving benzaldehyde (2a; 0.5 mmol), benzo-
On the other hand, in the case of ortho- and para-hy- phenone (2r; 0.5 mmol) and uracil 1 (2.0 mmol). Benzalde-
droxy-substituted benzaldehydes (entries e and f, respec- hyde reacted as described in Scheme 1, whereas benzo-
tively), low yields (75 and 73%, respectively) of the products phenone did not react at all. Unreacted benzophenone (2r)
were obtained probably due to the formation of intermo- and uracil 1 were recovered along with the desired product
lecular hydrogen-bonding with water.
3a.
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S. Das, A. J. Thakur
FULL PAPER
To extend the scope of the reaction further, we also
At this stage, the detailed mechanism is not fully under-
studied the reaction of 6-amino-1,3-dimethyluracil (1) with stood. A plausible mechanism for the reaction is shown in
dicarbaldehyde 6 (Scheme 3). The results are reported in Scheme 4. Mechanistically, the nucleophilic 5-position of 6-
Table 2 (entries a and b). In the case of an aliphatic dicarb- amino-1,3-dimethyluracil (1) attacks the carbon centre of
aldehyde, glutaraldehyde (entry b, Table 2) we obtained the the aldehyde 2 and is followed by elimination of a water
tetrakis-uracil adduct 8, but in the case of p-benzenedi- molecule. A second molecule of 1 then reacts at the nucleo-
carbaldehyde (entry a, Table 2) we obtained the bis-uracil philic 5-position to afford the product 3.
adduct 9 instead of the tetrakis-uracil adduct, as evidenced
6-Amino-1,3-dimethyluracil (1) is water-soluble. When
by the appearance of the aldehydic peak at δ = 9.96 ppm in the aldehyde, which is insoluble, is added to an aqueous
1
the H NMR spectrum and at δ = 192.04 ppm in the 13C solution of uracil 1 the reaction probably occurs at the
NMR spectrum of 9.
interface. As soon as the product forms, it precipitates ow-
ing to its hydrophobic nature, which might be the driving
force for the reaction.
Conclusions
The experimental procedure for the electrophilic substi-
tution is remarkably simple without the need for dry sol-
vents, an inert atmosphere or reflux conditions. The prod-
uct was purified by simple filtration without the need for
any further separation technique, that is, neither
chromatography (TLC/column chromatography) nor ex-
traction using organic solvent. Importantly, the separation
step in any synthesis involves most of the capital and op-
erating costs (60–80%) of the overall cost. Different steps
(reaction, separation and purification) contribute to the en-
vironmental footprint of the process.[36] Hence, our method
is environmentally benign (eliminating the use of organic
solvents in both the reaction and purification), safe and
cost effective. Note that no dehydrating agent, heat (hence
energy is saved), catalyst, surfactant or additive is required.
Moreover, protection of the –NH2 group is also not re-
quired. The present method opens a new avenue for the
synthesis of bis-uracils, which might be useful for exploring
bioactivities.
Scheme 3. Synthesis of tetrakis-uracil derivatives.
Table 2. Synthesis of the bis- and tetrakis-uracil derivatives 8 and
9.
Carbonyl compound 6
Time [h] M.p. [°C]
Yield [%][a]
a
b
p-(CHO)C6H4(CHO)
CHO(CH2)5CHO
7
7
301–303
194–195
86
89
In conclusion, we have developed a mild, chemoselective,
highly efficient, clean and truly “green” methodology for
the synthesis of aryl/alkyl/heteroaryl bis(6-amino-1,3-di-
methyluracil-5-yl)methanes by condensation of 6-amino-
1,3-dimethyluracil with all types of aldehydes (aromatic, ali-
phatic and heterocyclic) in water at room temperature.
Further exploration of “in water” reactions, both in
terms of applications and mechanism (experimentally and
theoretically), are in progress in our laboratory.
[a] Isolated yield.
Only a few examples of the nucleophilic nature[33] of the
5-position of uracil and its metal-binding capacity have
been reported.[34] Indole also shows similar nucleophilic be-
haviour at the 3-position and reacts with the carbonyl moi-
ety to produce bis-indolyl compounds.[35]
Experimental Section
General: Melting points were determined with a Büchi 504 appara-
tus. IR spectra were recorded as KBr pallets with a Nicolet (Impact
410) FT-IR spectrophotometer. 1H and 13C NMR spectra were re-
corded 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-Kα radiation (λ =
0.71073 Å). The structures were solved by SHELX97 and refined
by full-matrix least-squares on F2 (SHELX97).[37] Reactions were
monitored by thin-layer chromatography using aluminium sheets
with silica gel 60 F254 (Merck). Elemental analyses were carried out
Scheme 4.
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Eur. J. Org. Chem. 2011, 2301–2308

Synthesis of Bis(6-amino-1,3-dimethyluracilyl)methanes
with a Perkin–Elmer CHN analyser (2400 series II). Mass spectra
3097.30, 2941.31, 1688.03, 1594.43, 1497.32 cm–1 1H NMR
.
were recorded with a Waters Q-TOF Premier and Aquity UPLC (400 MHz, CDCl3): δ = 3.33 (s, 3 H, NCH3), 3.35 (s, 3 H, NCH3),
spectrometer. All the chemicals were used as received.
3.37 (s, 3 H, NCH3), 3.39 (s, 3 H, NCH3), 4.16 (d, J = 11.2 Hz, 1
H, CH=CH), 4.83 (d, J = 13.2 Hz, 1 H, CH=CH), 5.09 (s, 1 H,
CH), 6.15 (br. s, 1 H, NH2), 6.19 (br. s, 1 H, NH2), 7.21–7.48 (m,
5 H, arom.) ppm. 13C NMR (100 MHz, CDCl3): δ = 28.0 (NCH3),
28.1 (NCH3), 29.1 (NCH3), 29.2 (NCH3), 34.2 (CH), 36.1
(CH=CH), 39.3 (CH=CH), 86.3 and 86.8 (C-5 and CЈ-5), 126.2
(C-4, arom.), 128.4 (C-3 and C-5, arom.), 128.9 (C-2 and C-6,
arom.), 137.7 (C-1, arom.), 145.3 (C-6 and CЈ-6), 150.5 and 150.9
(C-2 and CЈ-2), 162.1 and 165.0 (C-4 and CЈ-4) ppm. MS: m/z =
424 [M]+. C21H24N6O4 (424.46): calcd. C 59.42, H 5.70, N 19.80;
found C 59.45, H 5.75, N 19.78.
General Procedure for the Synthesis of Bis-uracil 3: Distilled water
(30 mL) was added to 6-amino-1,3-dimethyluracil (1; 155 mg,
1 mmol) in a 100 mL round-bottomed flask and the mixture was
stirred at room temperature until all the 6-amino-1,3-dimethylura-
cil had dissolved. Benzaldehyde (54 mg, 0.5 mmol) was added drop-
wise to the 6-amino-1,3-dimethyluracil solution with constant stir-
ring and then after a few minutes the product appeared as a white
precipitate and stirring was continued for a further 1 h so that all
of the reactants were converted into product. The white precipitate
was filtered and collected to provide the pure product 3a in 95%
yield. A small amount of the product was dissolved in distilled
ethanol (98%) and then warmed. Then the solution was filtered,
allowed to cool and evaporated at room temp. to give square-
shaped white shining transparent crystals. The crystals were col-
lected and dried; m.p. 296–299 °C. The crystals are stable at room
temp. and also in an open environment for several days.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(4-methoxybenzylidene)bis-
[pyrimidine-2,4(1H,3H)-dione] (3c): Colour: white crystalline solid.
Solubility: insoluble in water, sparingly soluble in common organic
volatile solvents, soluble in aprotic polar solvents like DMF,
DMSO and DMAc. IR (KBr): ν
= 3358.89, 3195.07, 3083.58,
˜
max
2952.68, 1688.34, 1593.50, 1503.18, 1448.50 cm–1 1H NMR
.
(400 MHz, CDCl3): δ = 3.29 (s, 3 H, NCH3), 3.36 (s, 3 H, NCH3),
3.45 (s, 6 H, NCH3), 3.77 (s, 3 H, OCH3), 5.74 (s, 1 H, CH), 6.49
The same procedure was followed for the other substrates.
General Procedure for the Synthesis of Bis- and Tetrakis-uracil 8 and (br. s, 2 H, NH2), 6.70 (br. s, 2 H, NH2), 6.80 (d, J = 8.72 Hz, 2
9: Distilled water (30 mL) was added to 6-amino-1,3-dimethyluracil
(1; 155 mg, 1 mmol) in a 100 mL round-bottomed flask and the
H, arom.), 7.04 (d, J = 8.24 Hz, 2 H, arom.) ppm. 13C NMR
(100 MHz, CDCl3): δ = 29.2 (NCH3), 29.3 (NCH3), 29.3 (NCH3),
mixture was stirred at room temperature until all the 6-amino-1,3- 29.4 (NCH3), 35.1 (CH), 55.2 (OCH3), 87.9 and 89.1 (C-5 and CЈ-
dimethyluracil had dissolved. Then glutaraldehyde (25 mg,
0.25 mmol; entry 6b, Table 2) was added dropwise to the 6-amino-
1,3-dimethyluracil solution with constant stirring. After 3 h a yel-
lowish white precipitate appeared and stirring was continued for a
further 4 h so that all of the reactants were converted into product.
The yellowish white precipitate was filtered and collected. On dry-
ing we obtained the product 8 in 89% yield. A small amount of
the product was dissolved in distilled ethanol (98%) and warmed.
Then the solution was filtered, allowed to cool and evaporated at
room temp. to give square-shaped yellow shining transparent crys-
tals. The crystals were collected and dried; m.p. 194–195 °C. The
crystals are stable at room temp. and also in an open environment
for several days.
5), 113.4 (C-1, arom.), 127.7 (C-3 and C-5, arom.), 129.9 (C-2 and
C-6, arom.), 151.0 (C-6 and CЈ-6), 153.4 and 154.6 (C-2 and CЈ-2),
157.6 (C-4, arom.), 163.3 and 165.2 (C-4 and CЈ-4) ppm. MS: m/z
= 393 [M]+. C20H24N6O5 (428.45): calcd. C 56.07, H 5.65, N 19.62;
found C 56.10, H 5.68, N 19.65.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(4-chlorobenzylidene)bis-
[pyrimidine-2,4(1H,3H)-dione] (3d): Colour: white transparent crys-
talline solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
DMF, DMSO and DMAc. IR (KBr): ν
= 3346.99, 3156.01,
˜
max
3040.98, 2951.22, 1692.61, 1589.72, 1495.72 cm–1 1H NMR
.
(400 MHz, CDCl3): δ = 3.27 (s, 3 H, NCH3), 3.38 (s, 3 H, NCH3),
3.45 (s, 6 H, NCH3), 5.74 (s, 1 H, CH), 6.48 (br. s, 2 H, NH2), 6.68
(br. s, 2 H, NH2), 7.08 (d, J = 21.08 Hz, 2 H, arom.), 7.26 (d, J =
21.08 Hz, 2 H, arom.) ppm. 13C NMR (100 MHz, CDCl3): δ = 29.2
(NCH3), 29.3 (NCH3), 29.4 (NCH3), 29.7 (NCH3), 35.6 (CH), 88.5
and 88.6 (C-5 and CЈ-5), 127.9 (C-4, arom.), 128.1 (C-3 and C-5,
arom.), 131.4 (C-2 and C-6, arom.), 136.8 (C-1, arom.), 150.9 (C-
6 and CЈ-6), 153.2 and 154.5 (C-2 and CЈ-2), 163.3 and 164.6 (C-4
and CЈ-4) ppm. MS: m/z = 432 [M]+. C19H21ClN6O4 (432.87):
calcd. C 52.72, H 4.89, N 19.42; found C 52.73, H 4.86, N 19.38.
The same procedure was followed for 6a.
The following compounds were also prepared according to the ge-
neral procedure.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(benzylidene)bis[pyrimidine-
2,4(1H,3H)-dione] (3a): Colour: white shining transparent crystal-
line solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
DMF, DMSO and DMAc. IR (KBr): ν
= 3453.37, 3383.38,
˜
max
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(4-hydroxybenzylidene)bis-
[pyrimidine-2,4(1H,3H)-dione] (3e): Colour: transparent crystalline
solid. Solubility: soluble in water, sparingly soluble in common or-
ganic volatile solvents, soluble in aprotic polar solvents like DMF,
3197.94, 2993.08, 1695.96, 1654.14, 1587.29 cm–1 1H NMR
.
(400 MHz, CDCl3): δ = 3.27 (s, 3 H, NCH3), 3.36 (s, 3 H, NCH3),
3.44 (s, 6 H, NCH3), 5.79 (s, 1 H, CH), 6.48 (br. s, 2 H, NH2),
6.69 (br. s, 2 H, NH2), 7.14–7.25 (m, 5 H, arom.) ppm. 13C NMR
(100 MHz, CDCl3): δ = 28.4 (NCH3), 28.8 (NCH3), 29.1 (NCH3),
29.4 (NCH3), 35.7 (CH), 87.4 and 88.8 (C-5 and CЈ-5), 125.7 (C-
4, arom.), 126.6 (C-3 and C-5, arom.), 127.9 (C-2 and C-6, arom.),
138.1 (C-1, arom.), 150.9 (C-6 and CЈ-6), 153.1 and 154.4 (C-2 and
CЈ-2), 163.2 and 164.8 (C-4 and CЈ-4) ppm. MS: m/z = 398 [M]+.
C19H22N6O4 (398.42): calcd. C 57.28, H 5.57, N 21.07; found C
57.31, H 5.56, N 21.01.
DMSO and DMAc. IR (KBr): ν
= 3393.35, 3118.08, 2956.74,
˜
max
1664.76, 1601.04, 1498.95 cm–1. 1H NMR (400 MHz, [D6]DMSO):
δ = 2.98 (s, 3 H, NCH3), 3.01 (s, 3 H, NCH3), 3.04 (s, 3 H, NCH3),
3.47 (s, 3 H, NCH3), 5.69 (s, 1 H, CH), 7.16 (br. s, 2 H, NH2), 7.41
(br. s, 2 H, NH2), 6.72 (d, J = 8.72 Hz, 2 H, arom.), 6. 96 (d, J =
8.24 Hz, 2 H, arom.), 8.58 (s, 1 H, OH) ppm. 13C NMR (100 MHz,
[D6]DMSO): δ = 29.52 (2 NCH3), 29.55 (2 NCH3), 34.89 (CH),
114.85 (C-4, arom.), 127.52 (C-3 and C-5, arom.), 127.55 (C-2 and
C-6, arom.), 129.16 (C-1, arom.), 151.07 (C-6 and CЈ-6), 154.79 (C-
2 and CЈ-2) ppm. MS: m/z = 414 [M]+. C19H22N6O5 (414.42): calcd.
C 55.07, H 5.35, N 20.28; found C 55.04, H 5.33, N 20.25.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(cinnamylidene)bis[pyrimid-
ine-2,4(1H,3H)-dione] (3b): Colour: yellowish transparent crystal-
line solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(2-hydroxybenzylidene)bis-
[pyrimidine-2,4(1H,3H)-dione] (3f): Colour: transparent crystalline
DMF, DMSO and DMAc. IR (KBr): ν
= 3390.54, 3214.46,
˜
max
Eur. J. Org. Chem. 2011, 2301–2308
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2305

S. Das, A. J. Thakur
FULL PAPER
solid. Solubility: soluble in water, sparingly soluble in common or-
ganic volatile solvents, soluble in aprotic polar solvents like DMF,
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(2-furyl)bis[pyrimidine-
2,4(1H,3H)-dione] (3j): Colour: transparent crystalline solid. Solu-
bility: insoluble in water, sparingly soluble in common organic vol-
atile solvents, soluble in aprotic polar solvents like DMF, DMSO
DMSO and DMAc. IR (KBr): ν
= 3457.17, 3297.16, 3195.14,
˜
max
2973.08, 1694.16, 1657.21, 1583.23 cm–1 1H NMR (400 MHz,
.
CDCl3): δ = 3.09 (s, 3 H, NCH3), 3.32 (s, 3 H, NCH3), 3.48 (s, 3 and DMAc. IR (KBr): ν
= 3351.56, 3190.48, 3074.22, 2951.20,
˜
max
H, NCH3), 3.57 (s, 3 H, NCH3), 4.84 (s, 1 H, CH), 5.75 (s, 1 H, 1698.55, 1592.24, 1497.74 cm–1. H NMR (400 MHz, CDCl3): δ =
OH), 6.41 (br. s, 4 H, NH2), 7.05–7.25 (m, 5 H, arom.) ppm. 13C
3.29 (s, 3 H, NCH3), 3.42 (s, 9 H, NCH3), 5.65 (s, 1 H, CH), 5.98
NMR (100 MHz, CDCl3): δ = 27.6 (NCH3), 28.1 (NCH3), 29.2 (1 H, furan), 6.28 (1 H, furan), 6.51 (br., s, 2 H, NH2), 6.63 (br., s,
1
(NCH3), 29.3 (NCH3), 30.1 (CH), 87.8 and 93.3 (C-5 and CЈ-5),
115.5 (C-4, arom.), 123.4 and 125.2 (C-3 and C-5, arom.), 127.8
and 128.3 (C-2 and C-6, arom.), 150.4 and 150.5 (C-6 and CЈ-6),
151.3 and 151.5 (C-2 and CЈ-2), 154.3 (C-1, arom.), 161.2 and 164.0
(C-4 and CЈ-4) ppm. MS: m/z = 414 [M]+. C19H22N6O5 (414.42):
calcd. C 55.07, H 5.35, N 20.28; found C 55.10, H 5.33, N 20.22.
2 H, NH2), 7.24 (1 H, furan) ppm. 13C NMR (100 MHz, CDCl3):
δ = 28.6 (NCH3), 28.6 (NCH3), 29.3 (NCH3), 29.3 (NCH3), 31.8
(CH), 87.6 (C-5 and CЈ5), 105.9 (C-3, furan), 110.2 (C-4, furan),
141.0 (C-6 and CЈ-6), 150.9 (C-5, furan), 152.4 and 153.5 (C-2 and
CЈ-2), 164.1 (C-4 and CЈ-4) ppm. MS: m/z = 388 [M]+. C17H20N6O5
(388.38): calcd. C 52.57, H 5.19, N 21.64; found C 52.55, H 5.20,
N 21.62.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(4-methylbenzylidene)bis-
[pyrimidine-2,4(1H,3H)-dione] (3g): Colour: transparent crystalline
solid. Solubility: insoluble in water, sparingly soluble in common
organic volatile solvents, soluble in aprotic polar solvents like
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(2-thienyl)bis[pyrimidine-
2,4(1H,3H)-dione] (3k): Colour: transparent crystalline solid. Solu-
bility: insoluble in water, sparingly soluble in common organic vol-
atile solvents, soluble in aprotic polar solvents like DMF, DMSO
DMF, DMSO and DMAc. IR (KBr): ν
= 3358.52, 3152.81,
˜
max
3053.07, 2929.70, 1690.23, 1591.04, 1498.48, 1447.64 cm–1 1H
.
and DMAc. IR (KBr): ν
= 3361.56, 3327.33, 3057.73, 2982.55,
˜
max
1681.87, 1632.89, 1573.09 cm–1. H NMR (400 MHz, CDCl3): δ =
3.31 (s, 1 H, NCH3), 3.33 (s, 1 H, NCH3), 3.42 (s, 1 H, NCH3),
3.45 (s, 1 H, NCH3), 5.93 (s, 1 H, CH), 6.54 (br. s, 2 H, NH2), 6.68
(1 H, thiophene), 6.87 (1 H, thiophene), 6.91 (br. s, 2 H, NH2),
7.13 (1 H, thiophene) ppm. 13C NMR (100 MHz, CDCl3): δ =
29.32 (NCH3), 29.38 (NCH3), 29.41 (NCH3), 29.44 (NCH3), 33.3
(CH), 89.0 and 89.3 (C-5 and CЈ5), 123.4 and 124.0 (C-6 and CЈ-
6), 126.3 (C-3, thiophene), 144.4 (C-4, thiophene), 150.9 (C-5, thio-
phene), 153.2 and 153.9 (C-2 and CЈ-2), 163.5 and 164.5 (C-4 and
CЈ-4) ppm. MS: m/z = 404.13 [M]+. C17H20N6O4S (404.44): calcd.
C 50.48, H 4.98, N 20.78; found C 50.46, H 4.99, N 20.77.
1
NMR (400 MHz, CDCl3): δ = 2.30 (s, 3 H, CH3), 3.28 (s, 3 H,
NCH3), 3.37 (s, 3 H, NCH3), 3.45 (s, 6 H, NCH3), 5.75 (s, 1 H,
CH), 6.49 (br. s, 2 H, NH2), 6.69 (br. s, 2 H, NH2), 7.01–7.08 (m,
4 H, arom.) ppm. 13C NMR (100 MHz, CDCl3): δ = 20.8 (CH3),
28.3 (NCH3), 28.3 (NCH3), 29.6 (NCH3), 29.6 (NCH3), 35.6 (CH),
86.8 and 88.4 (C-5 and CЈ-5), 126.4 (C-4, arom.), 128.4 (C-3 and
C-5, arom.), 134.4 (C-2 and C-6, arom.), 135.5 (C-1, arom.), 150.9
(C-6 and CЈ-6), 153.5 and 154.5 (C-2 and CЈ-2), 163.2 and 164.4
(C-4 and CЈ-4) ppm. MS: m/z = 412 [M]+. C20H24N6O4 (412.45):
calcd. C 58.24, H 5.87, N 20.38; found C 58.21, H 5.84, N 20.31.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(4-nitrobenzylidene)bis[pyr-
imidine-2,4(1H,3H)-dione] (3h): Colour: brown transparent crystal-
line solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(methylene)bis[pyrimidine-
2,4(1H,3H)-dione] (3l): Colour: white transparent crystalline solid.
Solubility: insoluble in water, common organic volatile solvents,
soluble in aprotic polar solvents like DMF, DMSO and DMAc. IR
DMF, DMSO and DMAc. IR (KBr): ν
= 3394.02, 3189.69,
˜
max
1676.16, 1615.01, 1505.16 cm–1. H NMR (400 MHz, CDCl3): δ =
3.30 (s, 3 H, NCH3), 3.36 (s, 3 H, NCH3), 3.39 (s, 3 H, NCH3),
3.42 (s, 3 H, NCH3), 5.84 (s, 1 H, CH), 6.53 (br. s, 2 H, NH2), 6.68
(br. s, 2 H, NH2), 8.08 (d, J = 8.72 Hz, 2 H, arom.), 8.40 (d, J =
8.72 Hz, 2 H, arom.) ppm. 13C NMR (100 MHz, CDCl3): δ = 28.6
(NCH3), 29.1 (NCH3), 29.4 (NCH3), 29.7 (NCH3), 35.9 (CH), 86.7
and 88.2 (C-5 and CЈ5), 122.1 (C-2 and C-6, arom.), 128.1 (C-3
and C-5, arom.), 141.2 (C-1, arom.), 148.6 (C-4, arom.), 150.9 (C-
6 and CЈ-6), 153.4 and 154.9 (C-2 and CЈ-2), 163.3 and 165.1 (C-4
and CЈ-4) ppm. MS: m/z = 443 [M]+. C19H21N7O6 (443.42): calcd.
C 51.47, H 4.77, N 22.11; found C 51.43, H 4.78, N 22.13.
1
(KBr): ν
= 3386.70, 3155.75, 2927.21, 1682.97, 1619.94,
˜
max
1504.20 cm–1. H NMR (400 MHz, [D6]DMSO): δ = 3.19 (s, 3 H,
NCH3), 3.28 (s, 3 H, NCH3), 3.37 (s, 6 H, NCH3), 4.13 (s, 2 H,
CH2), 7.51 (br. s, 2 H, NH2), 7.70 (br. s, 2 H, NH2) ppm. 13C NMR
(100 MHz, [D6]DMSO): δ = 19.53 (CH2), 29.96 (2 NCH3), 30.07
(2 NCH3), 85.2 and 85.41 (C-5 and CЈ-5), 151.08 (C-6 and CЈ-6),
154.30 and 154.36 (C-2 and CЈ-2), 164.00 (C-4 and CЈ-4) ppm. MS:
m/z = 322 [M]+. C13H18N6O4 (322.32): calcd. C 48.44, H 5.63, N
26.07; found C 48.42, H 5.61, N 26.08.
1
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(ethylidene)bis[pyrimidine-
2,4(1H,3H)-dione] (3m): Colour: white transparent crystalline solid.
Solubility: insoluble in water, soluble in common organic volatile
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(3-nitrobenzylidene)bis[pyr-
imidine-2,4(1H,3H)-dione] (3i): Colour: brown transparent crystal-
line solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
solvents. IR (KBr): ν
= 3410.87, 3172.15, 2997.44, 2949.39,
˜
max
1680.66, 1621.14, 1493.60 cm–1. H NMR (400 MHz, CDCl3): δ =
1.66 (3 H, CH3), 3.31 (s, 6 H, NCH3), 3.46 (s, 6 H, NCH3), 4.43–
4.45 (m, 1 H, CH), 6.48 (br. s, 2 H, NH2), 6.91 (br. s, 2 H,
NH2) ppm. 13C NMR (100 MHz, CDCl3): δ = 16.1 (CH3), 26.3
(CH), 28.3 (NCH3), 28.8 (NCH3), 29.2 (NCH3), 29.5 (NCH3), 90.1
and 91.3 (C-5 and CЈ-5), 151.0 (C-6 and CЈ-6), 152.9 and 153.6 (C-
2 and CЈ-2), 164.2 and 164.4 (C-4 and CЈ-4) ppm. MS: m/z = 336.15
[M]+. C14H20N6O4 (336.35): calcd. C 49.99, H 5.99, N 24.99; found
C 49.99, H 5.98, N 24.97.
1
DMF, DMSO and DMAc. IR (KBr): ν
= 3396.10, 3196.67,
˜
max
1681.06, 1607.07, 1503.67, 1451.58 cm–1
.
1H NMR (400 MHz,
CDCl3): δ = 3.36 (s, 3 H, NCH3), 3.45 (s, 3 H, NCH3), 3.50 (s, 3
H, NCH3), 3.52 (s, 3 H, NCH3), 5.81 (s, 1 H, CH), 6.51 (br. s, 2
H, NH2), 6.69 (br. s, 2 H, NH2), 7.23–7.24 (m, 1 H, arom.), 7.41–
7.46 (m, 2 H, arom.), 7.95–8.08 (m, 1 H, arom.) ppm. 13C NMR
(100 MHz, CDCl3): δ = 28.6 (NCH3), 29.1 (NCH3), 29.4 (NCH3),
29.7 (NCH3), 35.9 (CH), 86.7 and 88.2 (C-5 and CЈ-5), 121.2 (C-
4, arom.), 122.1 (C-2, arom.), 128.9 (C-5, arom.), 133.3 (C-6,
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(butylidene)bis[pyrimidine-
arom.), 141.2 (C-1, arom.), 148.6 (C-3, arom.), 151.0 (C-6 and CЈ- 2,4(1H,3H)-dione] (3n): Colour: white transparent crystalline solid.
6), 153.4 and 154.9 (C-2 and CЈ-2), 163.4 and 165.1 (C-4 and CЈ-
4) ppm. MS: m/z = 443 [M]+. C19H21N7O6 (443.42): calcd. C 51.47,
H 4.77, N 22.11; found C 51.42, H 4.74, N 22.11.
Solubility: insoluble in water, soluble in common organic volatile
solvents. IR (KBr): ν = 3401.23, 3146.61, 2955.29, 1666.63,
˜
max
1606.54, 1493.54 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.91–0.93
2306
www.eurjoc.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 2301–2308

Synthesis of Bis(6-amino-1,3-dimethyluracilyl)methanes
(m, 3 H, CH3), 1.25–1.27 (m, 2 H, CH2), 2.16–2.21 (m, 2 H, CH2), data can be obtained free of charge from The Cambridge Crystallo-
3.31 (s, 3 H, NCH3), 3.35 (s, 3 H, NCH3), 3.45 (s, 6 H, NCH3),
4.20 (t, J = 8 Hz, 1 H, CH), 6.54 (br. s, 2 H, NH2), 6.67 (br. s, 2
H, NH2) ppm. 13C NMR (100 MHz, CDCl3): δ = 13.7 (CH3), 21.7
(CH), 27.8 (CH2), 28.4 (NCH3), 28.7 (NCH3), 29.1 (NCH3), 31.3
(NCH3), 31.6 (CH2), 88.6 and 89.6 (C-5 and CЈ-5), 150.6 and 150.7
(C-6 and CЈ-6), 152.5 and 153.6 (C-2 and CЈ-2), 163.7 and 164.3
(C-4 and CЈ-4) ppm. MS: m/z = 364.19 [M]+. C16H24N6O4 (364.40):
calcd. C 52.74, H 6.64, N 23.06; found C 52.72, H 6.66, N 23.08.
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supporting Information (see footnote on the first page of this arti-
1
cle): H and 13C NMR spectra of all compounds.
Acknowledgments
We gratefully acknowledge the financial assistance received from
the Department of Science and Technology (DST), New Delhi
(grant number SR/FTP/CS-58/2005). S. D. thanks the University
Grants Commission (UGC), New Delhi for a Rajiv Gandhi
National Fellowship.
6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(pentylidene)bis[pyrimidine-
2,4(1H,3H)-dione] (3o): Colour: white transparent crystalline solid.
Solubility: insoluble in water, soluble in common organic volatile
solvents. IR (KBr): ν
= 3396.53, 3106.74, 2952.08, 2859.75,
˜
max
1661.83, 1606.21, 1490.77 cm–1. H NMR (400 MHz, CDCl3): δ =
0.84–0.88 (m, 3 H, CH3), 1.26–1.30 (m, 4 H, CH2CH2), 2.05–2.21
(m, 2 H, CH2), 3.34 (s, 3 H, NCH3), 3.36 (s, 3 H, NCH3), 3.46 (s,
3 H, NCH3), 3.47 (s, 3 H, NCH3), 4.13–4.18 (m, 1 H, CH), 6.52
(br. s, 2 H, NH2), 6.94 (br. s, 2 H, NH2) ppm. 13C NMR (100 MHz,
CDCl3): δ = 13.3 (CH3), 21.8 (CH), 27.4 (CH2), 27.9 (CH2), 28.2
(NCH3), 28.4 (NCH3), 28.6 (NCH3), 30.4 (NCH3), 31.4 (CH2),
88.2 and 89.2 (C-5 and CЈ-5), 150.1 and 150.2 (C-6 and CЈ-6), 151.9
and 153.0 (C-2 and CЈ-2), 163.2 and 163.8 (C-4 and CЈ-4) ppm.
MS: m/z = 378.2 [M]+. C17H26N6O4 (378.43): calcd. C 53.96, H
6.93, N 22.21; found C 53.97, H 6.93, N 22.20.
1
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6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(glutarylidene)bis[pyrimid-
ine-2,4(1H,3H)-dione] (8): Colour: yellow transparent crystalline
solid. Solubility: insoluble in water, sparingly soluble in common
organic volatile solvents, soluble in aprotic polar solvents like
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DMF, DMSO and DMAc. IR (KBr): ν
= 3409.63, 3215.74,
˜
max
2938.88, 1664.95, 1603.34, 1495.23, 1446.66 cm–1 1H NMR
.
(400 MHz, [D6]DMSO): δ = 0.81–0.94 (m, 2 H, CH2), 1.22–1.34
(m, 4 H, 2 CH2), 3.09 (s, 3 H, NCH3), 3.25 (s, 3 H, NCH3), 3.34
(s, 18 H, NCH3), 3.94 (s, 1 H, CH), 4.12 (s, 1 H, CH), 6.78 (br. s,
2 H, NH2), 6.88 (br. s, 2 H, NH2), 7.19 (br. s, 2 H, NH2), 7.67 (br.
s, 2 H, NH2) ppm. 13C NMR (100 MHz, CDCl3 + [D6]DMSO): δ
= 22.7 (CH), 23.5 (CH), 27.4 (CH2), 27.7 (CH2), 28.0 (NCH3), 28.3
(NCH3), 28.7 (NCH3), 29.2 (NCH3), 29.4 (NCH3), 29.5 (NCH3),
29.7 (NCH3), 30.1 (NCH3), 31.7 (CH2), 85.9, 87.9, 89.3 and 89.4
(C-5, C-5, CЈ-5 and CЈ-5), 128.2, 128.6, 129.7 and 130.8 (C-6, C-6,
CЈ-6 and CЈ-6), 150.8, 150.9, 153.0 and 154.2 (C-2, C-2, CЈ-2 and
CЈ-2), 162.8, 163.4 and 164.0 (C-4, C-4, CЈ-4 and CЈ-4) ppm. MS:
m/z = 684.31 [M]+. C29H40N12O8 (684.71): calcd. C 50.87, H 5.89,
N 24.55; found C 50.88, H 5.90, N 24.54.
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6,6Ј-Diamino-1,1Ј,3,3Ј-tetramethyl-5,5Ј-(terephthaldibenzylidene)-
bis[pyrimidine-2,4(1H,3H)-dione] (9): Colour: transparent crystal-
line solid. Solubility: insoluble in water, sparingly soluble in com-
mon organic volatile solvents, soluble in aprotic polar solvents like
DMF, DMSO and DMAc. IR (KBr): ν
= 3420.99, 3110.18,
˜
max
2924.07, 1683.96, 1603.00, 1496.68 cm–1
.
1H NMR (400 MHz,
CDCl3): δ = 3.27 (s, 3 H, NCH3), 3.39 (s, 3 H, NCH3), 3.47 (s, 3
H, NCH3), 3.50 (s, 3 H, NCH3), 5.84 (s, 1 H, CH), 6.51 (br. s, 2
H, NH2), 6.69 (br. s, 2 H, NH2), 7.32 (d, J = 8 Hz, 2 H, arom.),
7.78 (d, J = 8 Hz, 2 H, arom.), 9.96 (s, 1 H, CHO) ppm. 13C NMR
(100 MHz, CDCl3): δ = 28.5 (NCH3), 29.0 (NCH3), 29.4 (NCH3),
29.7 (NCH3), 36.3 (CH), 86.7 and 88.7 (C-5 and CЈ-5), 127.4 (C-
4, arom.), 129.7 (C-3 and C-5, arom.), 134.3 (C-2 and C-6, arom.),
146.3 (C-1, arom.), 150.9 (C-6 and CЈ-6), 153.3 and 154.8 (C-2 and
CЈ-2), 165.1 (C-4 and CЈ-4), 192.0 (CHO) ppm. MS: m/z = 426.17
[M]+. C20H22N6O5 (426.43): calcd. C 56.33, H 5.20, N 19.17; found
C 56.33, H 5.21, N 19.18.
CCDC-750667 (for 3d), -775981 (for 3l) and -775982 (for 3j) con-
tain the supplementary crystallographic data for this paper. These
Eur. J. Org. Chem. 2011, 2301–2308
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
2307

S. Das, A. J. Thakur
FULL PAPER
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Received: November 24, 2010
Published Online: March 3, 2011
2308
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