Facile synthesis and biological evaluation of substituted 5-(1H-Indol-3-ylmethylene) pyrimidine-2,4,6-trione derivatives using L-Tyrosine in aqueous medium

Article abstract of DOI:10.14233/ajchem.2013.15364

L-Tyrosine as an efficient catalyst for the Knoevenagel condensation of substituted indole-3-aldehydes 1(a-d), N-methyl indole-3- aldehydes 4(a-d), N-ethyl indole-3-aldehydes 6(a-d) with barbituric acid (2) containing cyclic active methylene group to produce 3(a-d), 5(a-d) and 7(a-d), respectively in water at room temperature for 10 min. The antimicrobial activities of 3(a-d), 5(a-d) and 7(a-d) have been studied.

Full text of DOI:10.14233/ajchem.2013.15364

Asian Journal of Chemistry; Vol. 25, No. 15 (2013), 8741-8748
http://dx.doi.org/10.14233/ajchem.2013.15364
Facile Synthesis and Biological Evaluation of Substituted 5-(1H-Indol-3-ylmethylene)
pyrimidine-2,4,6-trione Derivatives Using L-Tyrosine in Aqueous Medium
*
G. THIRUPATHI , P.K. DUBEY and Y. BHARATHI KUMARI
Department of Chemistry, Jawaharlal Nehru Technological University Hyderabad, College of Engineering, Kukatpally, Hyderabad-500 085,
India
*Corresponding author: E-mail: thirupathigjntuh@gmail.com
(Received: 20 February 2013;
Accepted: 29 August 2013)
AJC-14039
L-Tyrosine as an efficient catalyst for the Knoevenagel condensation of substituted indole-3-aldehydes 1(a-d), N-methyl indole-3-
aldehydes 4(a-d), N-ethyl indole-3-aldehydes 6(a-d) with barbituric acid (2) containing cyclic active methylene group to produce
3(a-d), 5(a-d) and 7(a-d),respectively in water at room temperature for 10 min. The antimicrobial activities of 3(a-d), 5(a-d) and 7(a-d)
have been studied.
Key Words: Antibacterial activities, Antifungal activities, Indole-3-aldehyde, Barbituric acid, L-Tyrosine, Knoevenagel reaction.
L-Tyrosine is an known to be an efficient, bi-functional, zwitter
ionic and eco-friendly catalyst. It is available in both the enan-
tiomeric, (S)-tyrosine and (R)-tyrosine forms. The two func-
tional groups of tyrosine enable it to act both as an acid as
well as a base catalyst in chemical condensation reactions.
INTRODUCTION
Carbon-carbon bond formation reaction is the most
important reaction in organic synthesis1-4. The Knoevenagel
condensation is one such reactions which facilitates C-C double
bond formation and has been widely used in synthesis of
alkenes of biological significance5-9. These reactions are
usually catalyzed by bases10-17 such as ethylenediamine,
potassium fluoroiodide, primary, secondary amines and their
corresponding ammonium salts, Lewis acids18-20, zeolite21-23
and ionic liquids24-27 have also been added to the existing list of
substances that assisted Knoevenagel condensation in organic
synthesis.
EXPERIMENTAL
Melting points were measured in open capillary tubes and
are uncorrected. TLC was done on plates coated with silica
gel-G and spotting was done using iodine or UV lamp. IR
spectra were recorded using FT-IR in KBr phase. 1H and 13C
NMR spectra were recorded at 400 MHz, respectively.
General procedure for the preparation of 3 from 1: A
mixture of 1 (10 mmol), barbituric acid acid 2 (10 mmol) and
L-tyrosine (2 mmol) and water (25 mL) was stirred at room
temperature for a specified period of time (Table-1). After
completion of reaction (as shown by TLC checking), the mix-
ture was poured into ice cold water (50 mL). The separated
solid was filtered, washed with water (100 mL) and dried to
obtain crude product 3. The latter were then recrystallized from
ethyl acetate to afford pure compound 3. Compounds are
known and products were identified by spectral and melting-
point comparison with the authentic samples.
Knoevenagel condensation of meldrum’s acid and alde-
hydes gives rise to substrates for variety of reactions28. They
are used in cycloaddition reactions29, 1,4-conjugate addition
reactions and preparation of mono alkyl meldrum’s acid deri-
vatives, preparation of deuterated carboxylic acid derivatives.
These derivatives are also used in the preparation of ketenes
by α,β-pyrolysis, which are then used for preparation of diffe-
rent compounds such as cyclobutadiene derivatives30, α,β-
unsaturated esters31 and α,β-unsaturated amides32-33
.
Jones et al.34 reported the reaction of meldrum’s acid with
indole-3-carboxaldehyde under flash-vacuum pyrolysis to yield
the Knoevenagel derivative of 5-[(1H-indol-3-yl)methylene]-
2,2-dimethyl-1,3-dioxane-4,6-dione with 61 % yield. This
method is more time-consuming and not so good for the prepa-
ration of large amounts of these products. Moreover, it is a
very good intermediate for the preparation of anticancer drug38.
General procedure for the preparation of 5 from 3: A
mixture of compound 3 (10 mmol), DMS (10 mmol) and
Na2CO3 was physical grinded in solvent free condition under
grindstone method at room temperature for a specified period
of time (Table-1). After completion of reaction (as shown by
TLC checking), the mixture was poured into ice-cold water

8742 Thirupathi et al.
Asian J. Chem.
(50 mL). The separated solid was filtered, washed with water
(100 mL) and dried to obtain crude 5. The latter were then
recrystallised from ethyl acetate to afford pure 5. Compounds
are known and products were identified by spectral and
melting-point comparison with the authentic samples.
General procedure for the preparation of 7 from 3: A
mixture of compound 3 (10 mmol), DES (10 mmol) and
Na2CO3 was physical grinded in solvent free condition under
grindstone method at room temperature for a specified period
of time (Table-1). After completion of reaction (as shown by
TLC checking), the mixture was poured into ice-cold water
(50 mL). The separated solid was filtered, washed with
water(100 mL) and dried to obtain crude compound 7. The
latter were then recrystallised from ethyl acetate to afford pure
compound 7. Compounds are known and products were
identified by spectral and melting-point comparison with the
authentic samples.
s, 1H, NH proton of indole ring); 11.15-11 (brs, s, 2H, NH-
barbituric). 13C spectrum (DMSO-d6/TMS): δ 113.01, 117.74,
122.6, 123.6, 131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31
(N-CO-N); MS: m/z = 301.23 (M + 1).
5-(1-Methyl-1H-indol-3-ylmethylene)-pyrimidine-
2,4,6-trione (5a): Yellow solid; yield = 2.52 g (94 %); m.p.
247-249 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 4.01 (s, 3H, N CH3), 7.31-7.62
(m, 4H, aryl protons of the indole ring), 7.84 (s, 1H, α-proton
of the indole ring), 8.32-8.45 (s, 1H, vinylic proton of the
indole ring), 9.85-9.96 (br, s, 1H, NH proton of indole ring);
11.15-11. (brs, s, 2H, NH-barbituric). 13C spectrum (DMSO-
d6/TMS): δ 34.02 (N-CH), 113.01, 117.74, 122.6, 123.6,
3
131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N);
MS: m/z = 270.26 (M + 1).
5-(5-Methoxy-1-methyl-1H-indol-3-ylmethylene)-
pyrimidine-2,4,6-trione (5b): Yellow solid; yield = 2.78 g
(93 %); m.p. 241-243 ºC; IR (KBr, νmax, cm-1): 3210 (NH-
indole), 3040 (aromatic C-H), 1685 (C=O), 1674 (N-CO-N);
1620 (C=C). 1H NMR (DMSO-d6/TMS): δ 4.01 (s, 3H, N CH3),
3.45 (s, 3H, -OCH3), 7.31-7.62 (m, 4H, aryl protons of the
indole ring), 7.84 (s, 1H, α-proton of the indole ring), 8.32-
8.45 (s, 1H, vinylic proton of the indole ring), 9.85-9.96 (br,
s, 1H, NH proton of indole ring); 11.15-11 (brs, s, 2H, NH-
barbituric).13C spectrum (DMSO-d6/TMS): δ 34.02 (N-CH3),
53.11, 113.01, 117.74, 122.6, 123.6, 131.5, 140.4, 141.5,
144.95, 163.6 (C=O), 171.31 (N-CO-N); MS: m/z = 300.28
(M + 1).
5-(1H-Indol-3-ylmethylene)-pyrimidine-2,4,6-trione
(3a): Yellow solid; yield = 2.448 g (96 %); m.p. 251-253 ºC;
IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040 (aromatic C-H),
1685 (C=O), 1674 (N-CO-N); 1620 (C=C). 1H NMR (DMSO-
d6/TMS): δ 7.31-7.62 (m, 4H, aryl protons of the indole ring),
7.84 (s, 1H, α-proton of the indole ring), 8.32-8.45 (s, 1H,
vinylic proton of the indole ring), 9.85-9.96 (br, s, 1H, NH
proton of indole ring); 11.15-11 (brs, s, 2H, NH barbituric).
13C spectrum (DMSO-d6/TMS): δ 113.01, 117.74, 122.6,
123.6, 131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-
CO-N); MS: m/z = 256.23 (M + 1).
5-(5-Methoxy-1H-indol-3-ylmethylene)-pyrimidine-
2,4,6-trione (3b): Yellow solid; yield = 2.70 g (95 %); m.p.
243-245 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 3.83 (s, 3H, OCH3), 7.31-7.62
(m, 4H, aryl protons of the indole ring), 7.84 (s, 1H, α-proton
of the indole ring), 8.32-8.45 (s, 1H, vinylic proton of the
indole ring), 9.85-9.96 (br, s, 1H, NH proton of indole ring);
11.15-11.(brs, s, 2H, NH-barbituric). 13C spectrum (DMSO-
d6/TMS): δ 54.21, 113.01, 117.74, 122.6, 123.6, 131.5, 140.4,
141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N); MS: m/z =
286.25 (M + 1).
5-(5-Bromo-1-methyl-1H-indol-3-ylmethylene)-pyri-
midine-2,4,6-trione (5c):Yellow solid; yield = 3.27 g (94 %);
m.p. 265-266 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 4.01 (s, 3H, NCH3), 7.31-7.62
(m, 4H, aryl protons of the indole ring), 7.84 (s, 1H, α-proton
of the indole ring), 8.32-8.45 (s, 1H, vinylic proton of the
indole ring), 9.85-9.96 (br, s, 1H, NH proton of indole ring);
11.15-11. (brs, s, 2H, NH-barbituric). 13C spectrum (DMSO-
d6/TMS): δ 34.02 (N-CH3),113.01,117.74, 122.6, 123.6, 131.5,
140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N); MS:
m/z = 349.15 (M + 1).
5-(5-Bromo-1H-indol-3-ylmethylene)-pyrimidine-
2,4,6-trione (3c): Yellow solid; yield = 3.06 g (96 %); m.p.
281-282 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 7.31-7.62 (m, 4H, aryl protons
of the indole ring), 7.84 (s, 1H, α-proton of the indole ring),
8.32-8.45 (s, 1H, vinylic proton of the indole ring), 9.85-9.96
(br, s, 1H, NH proton of indole ring); 11.15-11 (brs, s, 2H,
NH-barbituric). 13C spectrum (DMSO-d6/TMS): δ 113.01,
117.74, 122.6, 123.6, 131.5, 140.4, 141.5, 144.95, 163.6
(C=O), 171.31 (N-CO-N); MS: m/z = 320.11 (M + 1).
5-(5-Nitro-1H-indol-3-ylmethylene)-pyrimidine-2,4,6-
trione (3d): Yellow solid; yield = 2.88 g (96 %); m.p. 262-
263 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040 (aro-
matic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).1H
NMR (DMSO-d6/TMS): δ 7.31-7.62 (m, 4H, aryl protons of
the indole ring), 7.84 (s, 1H, α-proton of the indole ring), 8.32-
8.45 (s, 1H, vinylic proton of the indole ring), 9.85-9.96 (br,
5-(1-Methyl-5-nitro-1H-indol-3-ylmethylene)-pyrimi-
dine-2,4,6-trione (5d): Yellow solid; yield = 2.95 g (94 %);
m.p. 254-257 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 4.01 (s, 3H, N CH3), 7.31-7.62
(m, 4H, aryl protons of the indole ring), 7.84 (s, 1H, α-proton
of the indole ring), 8.32-8.45 (s, 1H, vinylic proton of the
indole ring), 9.85-9.96 (br, s, 1H, NH proton of indole ring);
11.15-11. (brs, s, 2H, NH-barbituric). 13C spectrum (DMSO-
d6/TMS): δ 34.02 (N-CH3),113.01,117.74, 122.6, 123.6, 131.5,
140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N); MS:
m/z = 315.25 (M + 1).
5-(1-Ethyl-1H-indol-3-ylmethylene)-pyrimidine-2,4,6-
trione (7a): Yellow solid; yield = 2.66 g (94 %); m.p. 243-
245 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 1.53 (t, 3H, CH3), 4.03 (q, 2H,

Vol. 25, No. 15 (2013)
Facile Synthesis and Biological Evaluation of Substituted Pyrimidine-2,4,6-trione Derivatives 8743
CH2), 7.31-7.62 (m, 4H, aryl protons of the indole ring), 7.84
(s, 1H, α-proton of the indole ring), 8.32-8.45 (s, 1H, vinylic
proton of the indole ring), 9.85-9.96 (br, s, 1H, NH proton of
min. Thus, L-tyrosine has been found to be efficient and
eco-friendly catalyst for the Knoevenagel condensation
reaction of indole-3-carboxyaldehyde (1) and its N-methyl
derivative 4(a-d), N-ethyl derivative 6(a-d), each with barbi-
turic acid containing cyclic active methylene group (2).
The use of L-tyrosine as a catalyst helps to avoid the use of
environmentally unfavourable organic solvents as reaction
medium.
13
indole ring); 11.15-11 (brs, s, 2H, NH-barbituric). C spectrum
(DMSO-d6/TMS): δ 36.5,47.9,113.01, 117.74, 122.6, 123.6,
131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N);
MS: m/z = 284.28 (M + 1).
5-(1-Ethyl-5-methoxy-1H-indol-3-ylmethylene)-pyri-
midine-2,4,6-trione (7b): Yellow solid; yield = 2.91 g (93
%); m.p. 240-241 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole),
3040 (aromatic C-H), 1685 (C=O), 1674 (N-CO-N);
1620 (C=C). 1H NMR (DMSO-d6/TMS): δ 1.54 (t, 3H, CH3),
3.62 (s, 3H, OCH3), 4.15 (q, 2H, CH2), 7.31-7.62 (m, 4H, aryl
protons of the indole ring), 7.84 (s, 1H, α-proton of the indole
ring), 8.32-8.45 (s, 1H, vinylic proton of the indole ring), 9.85-
9.96 (br, s, 1H, NH proton of indole ring); 11.15-11 (brs, s,2H,
NH-barbituric). 13C spectrum (DMSO-d6/TMS): δ 36.5, 47.9,
56.5, 113.01, 117.74, 122.6, 123.6, 131.5, 140.4, 141.5,
144.95, 163.6 (C=O), 171.31 (N-CO-N); MS: m/z = 314.31
(M + 1).
The above reactions of 1(a-d), 4(a-d) and6(a-d) with
barbituric acid were attempted in the presence of various amino
acids like valine, glycine, alanine and Lysine but, there was
not much progress in the reactions as seen by TLC examination
of crude reaction mixtures. In the presence of phenyl alanine
in water at room temperature, there was a little bit of progress,
but the reaction was not completed for 16 h.
The above reactions of substituted indole-3-aldehydes
1(a-d), 4(a-d) and 6(a-d) with barbituric acid containing
cyclic active methylene group were attempted in the presence
of L-proline and L-tryptophan low yields were obtained for
1 h in water at room temperature.
5-(5-Bromo-1-ethyl-1H-indol-3-ylmethylene)-pyrimi-
dine-2,4,6-trione (7c): Yellow solid; yield = 3.40 g (94 %);
m.p. 261-262 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 1.51 (t, 3H, CH3), 4.23 (q, 2H,
CH2), 7.31-7.62 (m, 4H, aryl protons of the indole ring), 7.84
(s, 1H, α-proton of the indole ring), 8.32-8.45 (s, 1H, vinylic
proton of the indole ring), 9.85-9.96 (br, s, 1H, NH proton of
indole ring); 11.15-11 (brs, s, 2H, NH-barbituric). 13C spectrum
(DMSO-d6/TMS): δ 36.5, 47.9, 113.01, 117.74, 122.6, 123.6,
131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31 (N-CO-N);
MS: m/z = 363.18 (M + 1).
Treatment of substituted indole-3-carboxaldehydes 1(a-d)
and its N-methyl derivative 4(a-d), N-ethyl derivative 6(a-
d), each with barbituric acid containing cyclic active methylene
group (2) were attempted in the presence of various bases like
NaOH, KOH were too strong bases to result in more by-prod-
ucts. Low yield was obtained and 5 h reaction time is needed
using K2CO3, ammonium acetate, piperidine and triethylamine
as catalyst for condensation of substituted indole-3-aldehydes
1(a-d), 4(a-d) and 6(a-d) with barbituric acids containing
cyclic active methylene group (2) in water at room temperature.
Table-1 showed that the condensation of substituted
indole-3-aldehydes 1(a-d), 4(a-d)and 6(a-d) with electron
withdrawing group such as -NO2 and -Br at 5th position with
barbituric acid containing cyclic active methylene compounds
can be carried out in relatively shorter time and higher yield
than with electron donating group such as -OCH3 in water at
room temperature.
5-(1-Ethyl-5-nitro-1H-indol-3-ylmethylene)-pyrimi-
dine-2,4,6-trione (7d): Yellow solid; yield = 3.08 g (94 %);
m.p. 252-253 ºC; IR (KBr, νmax, cm-1): 3210 (NH-indole), 3040
(aromatic C-H), 1685 (C=O), 1674 (N-CO-N); 1620 (C=C).
1H NMR (DMSO-d6/TMS): δ 1.56 (t, 3H, CH3), 4.65 (q, 2H,
N CH2), 7.31-7.62 (m, 4H, aryl protons of the indole ring),
7.84 (s, 1H, α-proton of the indole ring), 8.32-8.45 (s, 1H,
vinylic proton of the indole ring), 9.85-9.96 (br, s, 1H, NH
proton of indole ring); 11.15-11 (brs, s, 2H, NH-barbituric).
13C spectrum (DMSO-d6/TMS): δ 36.5, 47.9, 113.01, 117.74,
122.6, 123.6, 131.5, 140.4, 141.5, 144.95, 163.6 (C=O), 171.31
(N-CO-N); MS: m/z = 329.28 (M + 1).
This method was very facile and convenient for the prepa-
ration of large amounts of Knoevenagel adducts with high
yields in less time. L-Tyrosine acted as base to induce the
reaction. The use of L-tyrosine as a catalyst helps to avoid the
use of environmentally unfavorable organic solvents (DMF,
C6H6, DMSO, CHCl3, CH3CN, etc.) as the reaction medium.
The L-tyrosine was readily reactive in water at room tempe-
rature compared to solvents such as methanol, ethanol, DMF,
C6H6, etc.; that is why the yield was also very high when the
reaction was carried out in water at room temperature.
In some cases, yields were very high when the nucleophile
was very active such as 5-nitroindole-3-carboxaldehyde,
N-methyl-5-nitroindole-3-carboxa-ldehyde and N-ethyl-5-
nitroindole-3-carboxaldehyde.
RESULTS AND DISCUSSION
Treatment of substituted indole-3-carboxaldehydes 1(a-
d) and its N-methyl derivative 4(a-d), N-ethyl derivative 6(a-
d), each with barbituric acid containing c yclic active methylene
group (2) in water at room temperature for 10 min resulted
corresponding Knoevenagel products 3(a-d), 5(a-d) and 7(a-
d) in excellent yields (93-96 %) (Scheme-I) (Table-1). L-
Tyrosine as an eco-friendly and efficient catalyst to induce
the reaction. Structures of all the products have been assigned
based on spectral and analytical data.
However, 5-methoxy indole-3-carboxaldehyde, N-methyl-
5-methoxyindole-3-carboxy aldehyde, N-ethyl-5-methoxy-
indole-3-carboxaldehyde, 5-bromoindole-3-carboxaldehyde,
N-methyl-5-bromo indole-3-carboxy aldehyde, N-ethyl-5-
bromoindole-3-carboxaldehyde under went condensation very
easily with barbituric acid in the presence of L-tyrosine in
water at room temperature.
In the absence of L-tyrosine, the reaction did not proceed
even after refluxing the reactants in water for 20 h. The use of
L-tyrosine as a catalyst helps to complete the reaction in 10

8744 Thirupathi et al.
Asian J. Chem.
O
R
R
O
O
NH
H2O
NH
NH
O
+
L-tyrosine/ 30 min
Water/ r.t.
+
O
O
N
O
N
N
H
CH3
4
CH3
5
2
DMS / Na2CO3 /
DMS / Na2CO3 /
20min / Physical grinding
15min / Physical grinding
R
O
R
O
NH
O
NH
L-tyrosine/ 30 min
H2O
+
+
O
O
N
N
H
O
Water/ r.t.
N
H
NH
H
O
1
3
2
DES / Na2CO3 /
DES / Na2CO3 /
20 min / Physical grinding
15min / Physical grinding
R
O
R
O
NH
NH
O
NH
L-tyrosine/ 30 min
Water/ r.t.
H2O
+
+
O
O
N
C2H5
N
O
N
C2H5
H
O
2
6
7
R = H, NO2, Br, OCH3
Scheme-I: Knoevenagel condensation of indole-3-aldehyde with barbituric acid in presense of L-tyrosine in water at room temperature
TABLE-1
SYNTHESIS OF NOVEL KNOEVENAGEL PRODUCTS BY USING L-TYROSINE
AS ECO-FRIENDLY CATALYST IN WATER AT ROOM TEMPERATURE
S. No.
1
Reactants
Product
Time (min)
Yield (%)
96
m.p. (ºC)
251-253
243-245
281-282
262-264
247-249
240-243
265-266
254-257
243-245
240-242
261-262
252-253
247-249
240-243
265-266
254-257
243-245
240-242
261-262
252-253
2
2
10
12
9
1a (R=H)
1b (R=OMe
1c (R=Br)
1d (R=NO2)
4a (R=H)
3a (R=H)
2
95
3b (R=OMe
3c (R=Br)
3d (R=NO2)
5a (R=H)
3
2
96
4
2
9
96
5
2
11
14
13
13
11
14
13
13
20
23
21
20
20
23
21
20
94
6
2
93
4b (R=OMe
4c (R=Br)
4d (R=NO2)
6a (R=H)
5b (R=OMe
5c (R=Br)
5d (R=NO2)
7a (R=H)
7
2
94
8
2
94
9
2
94
10
11
12
13
14
15
16
17
18
19
20
2
93
6b (R=OMe
6c (R=Br)
6d (R=NO2)
3a (R=H)
7b (R=OMe
7c (R=Br)
7d (R=NO2)
5a (R=H)
2
94
2
94
DMS
DMS
DMS
DMS
DES
DES
DES
DES
94
93
3b (R=OMe
3c (R=Br)
3d (R=NO2)
3a (R=H)
5b (R=OMe
5c (R=Br)
5d (R=NO2)
7a (R=H)
94
94
94
93
3b (R=OMe
3c (R=Br)
3d (R=NO2)
7b (R=OMe
7c (R=Br)
7d (R=NO2)
94
94
Treatment of 3(a-d) independently with DMS and DES
each, in the presence of Na2CO3 as base in solvent free condi-
tion under grindstone method at room temperature for 1 h
resulted corresponding 5(a–d)and 7(a–d), respectively in
excellent yields 93-94 % (Scheme-I). The compounds 5(a-d)
and 7(a-d) could also be synthesized in an alternative manner.
The compounds 4(a-d) and 6(a-d) were obtained from 1(a- d)
by alkylation with DMS and DES each, in the presence of
Na2CO3 as base in solvent free condition under grindstone
method at room temperature.
A comparative study of the progress of condensation
reactions 1(a-d), 4(a-d) and 6(a-d) with 2 were carried out in
different solvents contaning along with L-tyrosine as catalyst
and is summarized in Table-2.

Vol. 25, No. 15 (2013)
Facile Synthesis and Biological Evaluation of Substituted Pyrimidine-2,4,6-trione Derivatives 8745
necessary glassware were sterilized in hot air oven at 190 ºC
TABLE-2
PROGRESS OF REACTION IN DIFFERENT SOLVENT MEDIA
for 45 min. The Mueller HintonAgar and saline (0.82 % NaCl)
media were sterilized in autoclave (121 ºC, 15 psi, 20 min).
Inoculum was prepared in sterile saline (0.82 % NaCl) and
the optical density of all pathogens was adjusted to 0.10 at
625 nm on a chemito spectra scan UV 2600 spectrophoto-
meter that is equivalent to 0.5 Mc Farland standards. The
Mueller Hinton Agar plates were prepared by the pour plate
method. The activity of the compounds was tested by agar
well diffusion method. All the bacterial cells were cultured in
Mueller Hinton Agar plates and the compounds to be tested
were dissolved in N,N-dimethyl formamide and were soaked
in agar well and the Petri plates incubated at 37 ºC for 24 h.
The diameter (mm) of the zone of inhibition around each agar
disc was measured and results were recorded in Table-3. 3(a-
d), 5(a-d) and 7(a-d) compounds tested were found to have
excellent antibacterial activity against Klebsiella pneumoniae
and Escherichia coli. However, they were found to have very
good activity against Staphylococcus aureus and Bacillus
subtilis. 3(a-d) compounds tested were found to have more
antibacterial activities compare with 5(a-d) and 7(a-d) against
Klebsiella pneumoniae, Escherichia coli, Staphylococcus
aureus and Bacillus subtilis.
Time
(h)
Yield
(%)
Entry
Solvent
Temp. (ºC)
1
2
3
4
5
L-Tyrosine/water
L-Tyrosine/EtOH
1
2-5
8
r.t.
93-96
72-76
44-46
38-40
Nil
r.t.
L-Tyrosine/benzene
L-Tyrosine/DMSO
Without catalyst in water
r.t.
10
24
r.t.
r.t./reflux at
100
6
7
8
L-Tyrosine/DMF
L-Tyrosine/CH3CN
L-Tyrosine/CHCl3
7
r.t.
28-30
19-21
Nil
12
18
r.t.
r.t.
A plausible mechanism for the formation of 3 from 1 and
2 in the presence of L-tyrosine as catalyst is shown in the
Scheme-II. The reaction mechanism is supported by literature
reference.
In the mechanism shown in Scheme-II, L-tyrosine, in its
zwitter ionic form (Xb), abstracts a proton from barbituric
acid containing cyclic active methylene group (2) forming
the carbanion of barbituric acid (2I) which then attacks the
protonated indole-3-aldehydes (1I) forming the correspon-
ding intermediate (1II) that loses water to form the end product
3.
Antifungal activity: All the compounds 3(a-d), 5(a-d)
and 7(a-d) were screened for antifungal activity against37,38
Rhizoctonia solani, Fusarium oxysporum, Aspergillus niger
and Aspergillus flavus at concentrations of 50, 100, 200, 300
and 500 µg/mL. Mycostatin was used as a reference standard.
Potato dextrose agar (PDA) was used as basal medium for test
fungi. Glass petridishes used were sterilized. Sterilized melted
PDA medium (ca. 45ºC) was poured at the rate of 15 mL into
each petridish (90 mm). After solidification of the medium,
small portions of the mycelium of each fungus were spread
carefully over the centre of each PDA plate with the help of
Biological evaluation
Antibacterial activity:All the compounds substituted-5-
(1H-Indol-3-ylmethylene)-pyrimidine-2,4,6-trione, N-
alkyl derivatives 3(a-d), 5(a-d) and 7(a-d) were screened for
their antibacterial activities35 against gram positive bacteria
such asBacillus subtilis, Staphylo coccusaureus (ATCC6538)
and also a gainst gram-negative bacteria such as Klebsiella
pneumonia, Escherichia coli (ATCC8739) bacterial strains36
at concentrations of 50, 100, 200, 300 and 500 µg/mL. Strep-
tomycin was used as a reference standard. Petri plates and
O
O
O
OH
NH3
NH2
HO
HO
Xb
Xa
O
O
O
O
NH
NH
O
+
O
H
+
OH
O
NH
NH3
NH3
XC
H
NH
O
HO
HO
R
O
Xb
2I
2
Xb
O
H
H
O
R
OH
+
OH
O
OH
H2N
HO
+
NH2
H
N
H
Xa
N
H
HO
Xc
1I
1
O
R
O
O
O
R
H
H
HO
NH
NH
OH
+
NH
+
H2O
R
O
O
H2O
O
H
O
NH
N
NH
2
O
N
H
H
N
H
N
H
3
1I
1II
Scheme-II: Plausible mechanism for the formation of 3 from 1 and 2 in the presence of L-tyrosine in water at room temperature

8746 Thirupathi et al.
Asian J. Chem.
TABLE-3
ANTIBACTERIAL ACTIVITY OF 3(a-d), 5(a-d) AND 7(a-d) AGAINST
Klebsiella pneumonia, Escherichia Coli, Staphylococcus aureus AND Bacillus subtilis
Zone of inhibition in mm for concentration of
Types of bacteria
Compound
S. No.
No.
50 (µg/mL)
100 (µg/mL)
14
13
10
9
200 (µg/mL)
18
16
14
12
18
15
13
11
18
14
13
11
18
15
13
11
18
16
14
12
18
15
13
11
18
14
13
11
18
16
14
12
18
16
14
11
15
13
11
10
14
13
11
11
18
15
13
11
22
21
17
15
300 (µg/mL)
23
20
18
15
23
20
16
14
23
21
17
15
23
20
16
14
23
20
18
15
23
20
16
14
23
21
17
15
23
20
18
15
23
20
18
14
20
16
14
13
21
17
15
15
23
20
16
14
26
24
20
18
500 (µg/mL)
31
30
25
23
32
31
26
22
32
30
25
23
32
31
26
22
31
30
25
23
32
31
26
22
32
30
25
23
31
30
25
23
31
30
25
22
31
26
22
21
30
25
23
23
32
31
26
22
35
34
29
26
Klebsiella pneumonia
Escherichia coli
9
8
1
2
3a
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13
10
9
8
3b
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13.5
10
9.5
14
13
10
9
8.4
6
3
3c
Staphylococcus aureus
Bacillus subtilis
5
Klebsiella pneumonia
Escherichia coli
9
8
4
3d
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13
10
9
8
5
5a
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13
10
9
8
6
5b
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13.5
10
9.5
14
13
10
9
8.4
6
7
5c
Staphylococcus aureus
Bacillus subtilis
5
Klebsiella pneumonia
Escherichia coli
9
8
8
5d
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
9
14
13
10
9
8
9
7a
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
8
13
10
9
6
10
11
12
13
7b
Staphylococcus aureus
Bacillus subtilis
4
4
8
Klebsiella pneumonia
Escherichia coli
8.4
6
13.4
10
9.5
9.5
14
13
10
9
7c
7d
Staphylococcus aureus
Bacillus subtilis
5
5
Klebsiella pneumonia
Escherichia coli
9
8
Staphylococcus aureus
Bacillus subtilis
6
4
Klebsiella pneumonia
Escherichia coli
11
10
8
16
15
13
12
Streptomycin
Staphylococcus aureus
Bacillus subtilis
7
sterilized needles. Thus, each fungus was transferred to a
number of PDA plates, which were then incubated at (25 2)
ºC and ready for use after 5 days of incubation agar plates
were prepared by the pour plate method. The activity of the
compounds was tested by agar well diffusion method, freshly
seeded with the test organisms with sterile forceps. A control
agar well was also prepared on the test plates to compare the
effect of the test samples and to nullify the effect of solvent,
respectively. The plates were then kept in a refrigerator at 4 ºC
for 24 h so that the materials had sufficient time to diffuse
over a considerable area of the plates. After this, the plates
were incubated at 37 ºC for 72 h. N,N-Dimethyl formamide
was used as solvent to prepare desired solutions of the
compounds and also to maintain proper control. The diameter

Vol. 25, No. 15 (2013)
Facile Synthesis and Biological Evaluation of Substituted Pyrimidine-2,4,6-trione Derivatives 8747
TABLE-4
ANTIFUNGAL ACTIVITY OF 3(a-d), 5(a-d) AND 7(a-d) AGAINST
Rhizoctonia solani, Fusarium oxysporum, Aspergillus niger AND Aspergillus flavus
Zone of inhibition in mm for concentration of
Types of bacteria
Compound
S. No.
No.
50 (µg/mL)
100 (µg/mL)
14
13.8
10
11
13
13
9
200 (µg/mL)
18
17
300 (µg/mL)
23
500 (µg/mL)
31
30
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
Rhizoctonia solani
Fusarium oxysporum
Aspergillus niger
Aspergillus flavus
9
9
22.6
18
1
2
3a
6
14
25
6.5
8
13.6
15
18.3
20
25.2
31
8
14
11
19
14
30
22
3b
4
4.3
8.4
8
8.9
13.5
13
9.5
9
11.1
14
13.9
21
22.1
30
13
11
20
15
29
23
3
3c
5
5
10.8
18
14.8
23
23
9
14
13
10
9
32
31
8
15
12
20
15
4
3d
6
23
22
4
11
14
9
14
13
10
9
18
16
23
20
31
30
8
5
5a
6
14
12
18
15
25
23
4
9
14
13
10
9
18
15
23
20
32
31
8
6
5b
6
13
11
16
14
26
22
4
9
14
13.5
10
9.5
14
13
10
9
18
14
23
21
32
30
8.4
6
7
5c
13
11
17
15
25
23
5
9
18
15
23
20
32
31
8
8
5d
6
13
11
16
14
26
22
4
9
14
14
9
18
17
23
22
31
30
9
9
7a
5
12
15
23
23
4.8
9
8.7
14
13.9
10
9.7
14
13.5
10
9.5
13
12
8
11.8
18
14.6
23
32
9
18
12
22.7
15
31.8
23
10
11
12
13
7b
7c
6
5.4
9
11
14.6
23
22
18
17
32
31
8.4
5.3
5
22
15
11
11
24
23
14.7
22
8
17
16
30
29
8
21
7d
4
11.2
11
14.3
14
22
22
4
8
13
13
9.2
9
16
16
11
11
20
19
28
27
35
35
Mycostanin
14.6
14
21
20
30
29
(mm) of the zone of inhibition around each agar well was
measured and results were recorded in Table-4.
Rhizoctonia solani, Fusarium oxysporum, Aspergillus niger
and Aspergillus flavus.
3(a-d), 5(a-d) and 7(a-d) compounds tested were found
to have very good antifungal activity against Rhizoctonia solani
and Fusarium oxysporum. However, they were found to good
activity against Aspergillus niger and Aspergillus flavus.
3(a-d) compounds tested were found to have more anti-
fungal activities compare with 5(a-d) and 7(a-d) against
Conclusion
In summary, L-tyrosine has been employed as efficient,
eco-friendly catalyst for the preparation of substituted-5-(1H-
Indol-3-ylmethylene)-pyrimidine-2,4,6 trione derivatives
by Knoevenagel reaction in water at room temperature. This

8748 Thirupathi et al.
Asian J. Chem.
10. U.V. Desai, D.M. Pore, R.B. Mane, S.B. Solabanavar and P.P. Wadgaonkar,
Synth. Commun., 34, 25 (2004).
method is applicable to a wide range of indole-3-carboxyl-
dehydes, including N-substituted indole-3-carboxyaldehydes.
The attractive features of this procedure are the mild reaction
conditions, high conversions, operational simplicity and
inexpensive and ready availability of the catalyst, all of which
make it a useful and attractive strategy for the preparation
of substituted-5-(1H-indol-3-ylmethylene)-pyrimidine-2,4,6-
trione derivatives in water at room temperature. The antibac-
terial and antifungal activities of 3(a-d), 5(a-d) and 7(a-d) have
been studied. 3(a-d), 5(a-d) and 7(a-d) compounds tested were
found to have excelent antibacterial activities against Klebsiella
pneumoniae and Escherichia coli. 3(a-d) compounds tested
were found to have excelent antibacterial activities compare
with 5(a-d) and 7(a-d) against Klebsiella pneumoniae and
Escherichia coli. However, they were found to very good
activities against Rhizoctonia solani and Fusarium oxysporum.
3(a-d) compounds tested were found to have very good anti-
fungal activities compare with 5(a-d) and 7(a-d) against
Rhizoctonia solani and Fusarium oxysporum.
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