Synthesis and in vitro evaluation of the antifungal activities of dihydropyrimidinones

Article abstract of DOI:10.1016/j.bmcl.2008.10.063

Copper (II) chloride in the absence of any solvent, efficiently catalyses the synthesis of dihydropyrimidinones (80-96% yields) by the Biginelli reaction. Six compounds were selected and examined their antifungal activities against the radial growth of th

Full text of DOI:10.1016/j.bmcl.2008.10.063

Bioorganic & Medicinal Chemistry Letters 18 (2008) 6462–6467
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Synthesis and in vitro evaluation of the antifungal activities
of dihydropyrimidinones
a
b
b
Okram Mukherjee Singh a, , Sarangthem Joychandra Singh , Mutum Babita Devi , Laitonjam Nalini Devi ,
*
Nameirakpam Irabanta Singh b, Sang-Gyeong Lee c,
a Department of Chemistry, Manipur University, Canchipur, Imphal 795003, Manipur, India
*
b Aerobiology, Microbiology & Plant Pathology Laboratory, Department of Life Sciences, Manipur University, Canchipur, Imphal 795003, Manipur, India
c Department of Chemistry & Research Institute of Life Science, Gyeongsang National University, JinJu, GyeongNam 660-701, South Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Copper (II) chloride in the absence of any solvent, efficiently catalyses the synthesis of dihydropyrimid-
inones (80–96% yields) by the Biginelli reaction. Six compounds were selected and examined their anti-
fungal activities against the radial growth of three fungal species viz., Trichoderma hammatum,
Trichoderma koningii and Aspergillus niger.
Received 16 August 2008
Accepted 15 October 2008
Available online 18 October 2008
Ó 2008 Published by Elsevier Ltd.
Keywords:
Dihydropyrimidine
Solvent-free
Antifungal activity
Owing to their remarkable pharmacological properties such as
calcium channel blockers, antitumor and antiinflammatory activi-
ties, dihydropyrimidinones and their derivatives have increasingly
attracted the attention of synthetic chemists.1–5 Moreover, the
dihydropyrimidine-5-carboxylate core has been found in several
marine natural products which are potent HIVgp-120-CD4
inhibitors.6,7
However, despite the potential utility of dihydropyrimidines as
bioactive compounds, their antifungal activities are very rarely
studied.8 Thus we have aimed at further investigation of these syn-
thesized dihydropyridine derivatives as antifungal potential using
Trichoderma hammatum, Trichoderma koningii and Aspergillus niger
as model pathogens.
vent-free conditions. The antifungal activities of six of the selected
compounds are also reported.
The reaction of benzaldehyde 1 (10 mmol), ethylacetoacetate 2
(10 mmol) and urea 3 (12 mmol) was investigated previously using
20 mol% CuCl2ꢀ2H2O at 100 °C for 1 h. The heterogeneous reaction
mixture containing the solid cupric chloride was stirred rapidly.
Cupric chloride and urea dissolves gradually as the reaction pro-
ceeds and after 20 min the mixture turns to be clear oil. After
30 min of stirring, the oil starts solidifying and the solid mass
was heated under the same temperature for 1 h (monitored by
TLC). The resulting solid was crushed, washed with cold water
(200 mL) and filtered. The solid was dried and recrystallized from
hot ethanol to afford the analytically pure product 4a with 96%
yield (Scheme 1).
The same process was successfully extended to a wide range of
structurally varied aldehydes 1, urea/thiourea 3 and b-dicarbonyl
compounds 2, to yield the corresponding 3,4-dihydropyrimidin-
2(1H)-ones 4b–n (Table 1) in excellent yields (80–96%). Many of
the pharmacological relevant substitution patterns on the aromatic
ring could be introduced with high efficiency. Aromatic aldehydes
carrying electron-donating substituent afforded high yields of
products in high purity. The products obtained under solvent-free
conditions are of high purity and do not require any chromato-
graphic separation.15
Polyfunctionalized dihydropyrimidines are prepared by a multi-
component reaction (MCR) that was first reported by Biginelli in
1893, involving a one-pot condensation of an aldehyde, b-ketoester
and urea under strongly acidic conditions.9 Recently, a variety of
methods for promoting the Biginelli reaction including solid phase
12
reactions,10 microwave irradiation,11 and catalytic reactions
have been developed.
In continuation of our studies on the cupric chloride promoted
intramolecular ring cyclization13 and C–C bond forming reac-
tions,14 we are reporting herewith a simple and practical method
for the synthesis of dihydropyrimidinones by an improved Biginelli
protocol using catalytic amount of CuCl2ꢀ2H2O chloride under sol-
The antifungal activity of compounds 4a–n on T. hammatum, T.
koningii and A. niger growth and was evaluated. The results of
in vitro antifungal activities showed that the title compounds were
active against nearly all fungi tested to some extent. Most deriva-
* Corresponding author. Tel.: +91 0385 2435307.
E-mail address: ok_mukherjee@yahoo.co.in (O.M. Singh).
0960-894X/$ - see front matter Ó 2008 Published by Elsevier Ltd.
doi:10.1016/j.bmcl.2008.10.063

O. M. Singh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6462–6467
6463
C6H5
O
C6H5
H
O
H
O
1
O
O
O
EtO
N
+
20mol%CuCl2.2H2O
100oC
CH3
H2N
NH2
OC2H5
H3C
N
H
2
3
4a, 96%
Scheme 1.
Table 1
CuCl2ꢀ2H2O-catalyzed synthesis of dihydropyrimidines under solvent-free conditions.
O
R1
O
O
O
X
H
R2O
N
20mol% CuCl2.2H2O
NH2
+
OR2
+
R1
H
100oC
CH3
H2N
H3C
N
H
4a-n
X
3
1
2
Dihydropyridines
R1
R2
X
Yield (%)
Mp (°C) found
Mp (°C) reported
4a
4b
4c
4d
4e
4f
4g
4h
4i
C6H5
C6H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
C2H5
O
S
O
S
96
90
95
86
85
85
96
90
92
90
208–209
208–209
199–200
811–182
209–210
253–254
200–202
237–238
215–216
205–206
209–21012g
207–20812e
200–20212h
183–18512b
209–21012e
256–25812j
199–20112k
236–23812g
216–21712g
205–20612e
2-HOC6H4
2-HOC6H4
4-Me2NC6H4
4-Me2NC6H4
4-CH3OC6H4
4-HOC6H4
4-ClC6H4
S
O
O
O
O
O
4j
4-CH3C6H4
H3CO
4k
4l
C2H5
C2H5
C2H5
C2H5
O
O
O
O
90
80
92
89
174–175
250–252
188–190
247–248
—
—
—
—
H3CO
N
O
4m
4n
O
tives showed significant in vitro antifungal activities against tested
fungi. However, we have selected the best six compounds (4a–f)
exhibiting higher growth inhibition of the tested fungi with low
minimum inhibitory concentration (MIC)16 values included in the
solutions of tested compounds were prepared in acetone. Each
compound from the stock solution was added to the molten steril-
ized PDA medium in conical flasks separately to get a final concen-
tration of 0.5%, 1%, 3%, 5% and 7%, respectively. Each PDA medium
(20 mL) containing the compounds of the five different concentra-
tions was mixed thoroughly and poured into each 90 mm
petriplate.
Petriplates without any chemical compounds serve as control.
In each case, three replicates were taken. The petriplates after
solidification were inoculated separately with mycelial disc
(9 mm) of test fungi taken from 4 days old pure cultures aseptically
range of 0.025–0.35 lg/mL and a detailed report of the evaluation
of the six selected compounds are given below.
Poison food technique of Falck17 was used for in vitro study of
the antifungal activities. The effect of six different chemical com-
pounds 4a–f on the radial growth of three fungal species viz., T.
hammatum, T. koningii and A. niger was assessed by amending
the compounds in potato dextrose agar (PDA) medium.18 Stock

6464
O. M. Singh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6462–6467
and incubated at 25 1 °C in B.O.D. incubator till the mycelial
growth in the control reached a maximum growth. The radial
growth of the test fungi were recorded at 24 h intervals by measur-
ing the colony diameter, compared with control, were taken as a
measure of fungitoxicity. Growth inhibition (%) of test fungus
was determined by using the formula given by Vincent.19
fungi by these six compounds in relation to untreated plates are
also provided (Table 2.1–7.1). Regarding T. hammatum, the highest
growth inhibition, that is, 100% growth inhibition was shown by
compound 4a at 7% concentration (0.35 lg/mL) followed by com-
pound 4d and 4e, respectively. After 24 and 48 h, 50% growth inhi-
bition was shown at 3% concentration of all the compounds and
after 72 h except compounds 4b and 4e, the remaining compounds
4a, 4c, 4d and 4f show 50% growth inhibition.
The increase growth of T. koningii and A. niger over control were
also recorded from 0.5% to 1% of some compounds. In case of T.
koningii, highest growth inhibition was shown by the compound
4c, followed by 4a and 4e, respectively, at 7% concentration.
Control ꢁ Treatment
Growth inhibition ð%Þ ¼
ꢂ 100
Control
The effect of six compounds 4a-f on radial growth (colony
diameter) of the three fungal species are presented in Table 2–7
4a–f and the percent inhibition on radial growth of the three test
Table 2
Evaluation of different concentrations of dihydropyrimidine 4a on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
24 h
48 h
72 h
24 h
72 h
24 h
48 h
72 h
9.66
12.33
10.41
4.41
0
0.5
1
3
5
14.66
13.00
11.00
2.62
—
48.25
32.33
37.66
13.50
1.50
81.00
79.00
71.00
29.66
5.50
—
11.66
11.00
10.25
—
—
—
31.50
25.75
25.00
11.87
—
78.25
77.00
69.75
23.33
6.62
2.16
2.58
1.50
0.66
0.33
—
4.41
7.25
5.00
2.08
0.83
0.91
2.58
2.25
7
—
—
—
3.50
—, no growth.
Table 2.1
Inhibition rates of radial growth (%) of test fungi by different concentrations of dihydropyrimidine 4a (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
48 h 72 h
32.99
Trichoderma koningii
Aspergillus niger
24 h
11.32
24 h
5.66
12.09
100
100
100
48 h
18.25
20.63
62.31
100
100
72 h
1.59
10.86
70.18
91.53
95.52
24 h
0.00 (19.44)
30.55
69.44
84.72
48 h
72 h
0.5
1
3
5
7
2.46
12.34
63.38
93.20
0.00 (64.39)
0.00 (13.37)
52.83
81.17
79.36
0.00 (27.63)
0.00 (7.76)
54.34
73.29
76.70
24.96
82.12
21.94
72.02
96.89
100
100
100
100
100
The values in parentheses denoted percentage of increase growth over control.
Table 3
Evaluation of different concentrations of dihydropyrimidine 4b on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
48 h
5.50
24 h
48 h
72 h
24 h
72 h
24 h
72 h
8.25
17.00
14.50
5.25
3.66
—
0
0.5
1
3
5
18.50
15.33
9.66
6.08
2.00
—
64.33
58.66
52.33
20.83
4.50
81.00
81.00
81.00
50.50
4.08
17.33
23.58
22.00
7.62
1.87
1.50
55.33
64.33
57.50
17.66
7.00
78.66
81.00
81.00
29.33
15.87
12.25
3.00
7.00
3.00
2.00
2.00
—
10.83
8.25
2.87
2.50
—
7
—
3.25
5.00
Table 3.1
Inhibition rates of radial growth (%) of test fungi by different concentrations of dihydropyrimidine 4b (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
24 h 48 h 72 h
8.81
Trichoderma koningii
Aspergillus niger
48 h
0.00 (96.90)
0.00 (50.00)
47.81
24 h
0.00 (36.06)
0.00 (26.94)
56.03
89.20
91.34
48 h
0.00 (16.26)
0.00 (3.92)
68.08
87.34
90.96
72 h
0.00 (2.97)
0.00 (2.97)
62.71
79.82
84.42
24 h
0.00 (133.00)
0.00
33.33
33.33
100.00
72 h
0.5
1
3
5
7
17.13
47.78
67.13
89.18
100.00
0.00
0.00
0.00 (106.06)
0.00 (75.75)
36.36
55.63
100.00
18.65
67.62
37.65
94.96
95.98
93.00
54.54
100.00
100.00
The values in parentheses denoted percentage of increase growth over control.

O. M. Singh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6462–6467
6465
Table 4
Evaluation of different concentrations of dihydropyrimidine 4c on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
24 h
48 h
72 h
24 h
72 h
24 h
48 h
72 h
0
0.5
1
3
5
19.00
20.08
15.00
6.87
2.00
—
52.00
62.16
40.33
16.25
3.00
77.83
81.00
65.50
31.83
3.83
17.25
18.37
18.25
8.50
3.50
—
48.00
53.75
45.50
29.37
14.00
—
74.50
79.25
74.00
55.75
33.00
2.00
5.00
5.16
5.37
3.83
3.00
—
12.00
7.83
9.87
4.25
4.12
—
14.00
9.33
11.75
5.50
4.75
1.00
7
—
2.50
—, no growth.
Table 4.1
Inhibition rates of radial growth (%) of test fungi by different concentrations of dihydropyrimidine 4c (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
Trichoderma koningii
Aspergillus niger
24 h
0.00 (5.68)
21.05
63.84
89.47
100.00
48 h
72 h
0.00 (4.07)
15.84
59.10
95.07
96.78
24 h
0.00 (6.49)
0.00 (5.79)
50.72
79.71
100.00
48 h
0.00 (11.97)
5.20
38.81
70.83
100.00
72 h
0.00 (6.37)
0.67
25.16
55.70
97.31
24 h
0.00 (3.20)
0.00 (7.40)
37.60
40.00
48 h
72 h
0.5
1
3
5
7
0.00 (19.53)
22.44
68.75
94.23
100.00
34.75
17.75
64.58
65.66
100.00
33.35
16.07
60.71
66.07
92.85
100.00
The values in parentheses denoted percentage of increase growth over control.
Table 5
Evaluation of different concentrations of dihydropyrimidine 4d on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
24 h
48 h
72 h
24 h
72 h
24 h
48 h
72 h
0
0.5
1
3
5
13.25
9.75
6.66
2.50
—
51.16
48.00
24.83
9.75
—
80.66
81.00
49.83
19.00
2.00
11.41
13.66
10.00
5.66
—
32.00
49.00
36.33
30.66
2.75
80.00
81.00
68.50
53.83
9.33
3.33
6.33
2.66
1.50
1.25
1.25
5.66
13.00
11.00
3.50
2.83
2.16
7.83
15.16
16.00
6.00
5.33
5.00
7
—
—
1.33
—
2.00
7.16
—, no growth.
Table 5.1
Inhibition rates of radial growth (%) of test fungi by different concentrations dihydropyrimidine 4d (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
48 h 72 h
61.76 0.00 (0.42)
Trichoderma koningii
Aspergillus niger
48 h
0.00 (129.68)
0.00 (94.34)
38.16
24 h
26.41
24 h
0.00 (19.71)
12.35
50.39
100.00
100.00
48 h
0.00 (53.12)
0.00 (113.53)
4.18
91.40
93.75
72 h
0.00 (1.25)
14.37
32.71
88.33
91.05
24 h
0.00 (90.09)
20.12
54.95
62.46
62.46
72 h
0.5
1
3
5
7
0.00 (93.61)
0.00 (104.34)
23.37
31.92
36.14
49.73
81.13
51.46
80.94
38.22
76.44
97.52
98.35
100.00
100.00
100.00
100.00
50.00
61.83
The values in parentheses denoted percentage of increase growth over control.
After 24, 48 and 72 h, 50% growth inhibition was shown at 3%
concentration of the compounds 4a, 4b and 4f.
and compounds 4b, 4e and 4f were the most potent against A. ni-
ger, with MIC value of 0.35 g/mL each.
l
Similarly, 100% growth inhibition of A. niger were recorded from
the compounds 4b, 4e and 4f, respectively. At 3% concentration,
the compounds 4a and 4f show 50% growth inhibition of A. niger.
Inhibitory effects of the six compounds on each test fungus
were different. Thus compound 4a was the most potent against
T. hammatum resulting in 100% growth inhibition with MIC value
In conclusion, a broad range of structurally diverse 1,3-dicar-
bonyl compounds, aldehydes and urea/thiourea are subjected un-
der the one-pot Biginelli cyclocondensation catalyzed by cupric
chloride under solvent-free conditions to produce the correspond-
ing dihydropyrimidinones. In view of the simplicity, environmen-
tally friendly nature and high yields, the present procedure of the
synthesis of dihydropyrimidin-2(1H)-ones provides a simple, effi-
cient, cost-effective and green modification of the Biginelli’s reac-
of 0.35
lg/mL. The radial growth of T. koningii after 24 and 48 h
were found to be inhibited completely (100%) by compound 4c

6466
O. M. Singh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6462–6467
Table 6
Evaluation of different concentrations of dihydropyrimidine 4e on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
24 h
48 h
72 h
24 h
72 h
24 h
48 h
72 h
8.33
16.66
16.00
4.00
1.80
—
0
0.5
1
3
5
14.00
12.75
11.00
3.50
—
44.33
42.00
38.83
11.33
—
75.50
69.16
65.00
45.00
2.50
13.00
15.00
12.50
7.58
1.00
—
32.00
38.00
37.83
26.00
4.41
74.00
76.00
75.00
62.33
8.66
2.50
4.00
2.16
1.75
—
5.00
10.16
9.33
3.00
—
7
—
—
1.83
1.50
6.58
—
—
—, no growth.
Table 6.1
Inhibition rates of radial growth (%) of test fungi by different concentrations of dihydropyrimidine 4e (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
24 h 48 h 72 h
5.25
Trichoderma koningii
Aspergillus niger
48 h
0.00 (103.20)
0.00 (86.60)
40.00
24 h
0.00 (15.38)
3.84
41.69
92.30
100.00
48 h
0.00 (18.75)
0.00 (18.21)
18.75
86.21
95.31
72 h
0.00 (2.70)
0.00 (1.35)
15.77
88.29
91.10
24 h
0.00 (60.00)
13.60
30.00
100.00
100.00
72 h
0.5
1
3
5
7
8.92
21.42
8.39
13.90
40.39
96.68
97.57
0.00 (100.00)
0.00 (92.07)
51.98
78.39
100.00
12.40
74.44
75.00
100.00
100.00
100.00
100.00
100.00
100.00
The values in parentheses denoted percentage of increase growth over control.
Table 7
Evaluation of different concentrations of dihydropyrimidine 4f on the growth of the test fungi (average of three replicates).
Concentration (%)
Radial growth (mm)
Trichoderma koningii
48 h
Trichoderma hammatum
Aspergillus niger
24 h
48 h
72 h
24 h
72 h
24 h
48 h
72 h
0
0.5
1
3
5
15.83
17.25
16.33
3.58
2.50
—
55.33
57.16
56.16
13.66
3.66
81.00
81.00
81.00
21.83
10.66
5.00
12.50
12.00
11.33
2.00
—
31.00
28.00
16.00
11.00
4.00
78.33
42.66
40.50
31.66
16.33
15.66
3.50
2.16
2.00
—
—
—
12.00
7.00
6.33
3.00
1.50
—
18.66
12.00
10.00
4.83
2.16
—
7
2.00
—
4.00
—, no growth.
Table 7.1
Inhibition rates of radial growth (%) of test fungi by different concentrations of dihydropyrimidine 4f (average of three replicates).
Concentration (%)
Percentage inhibition of radial growth over control (mm)
Trichoderma hammatum
Trichoderma koningii
Aspergillus niger
24 h
0.00 (8.97)
0.00 (3.15)
77.38
84.20
100.00
48 h
72 h
0.00
0.00
73.04
86.83
93.82
24 h
4.00
9.36
84.00
100.00
100.00
48 h
9.67
48.38
64.51
87.09
87.09
72 h
24 h
48 h
72 h
0.5
1
3
5
7
0.00 (3.30)
0.00 (1.50)
75.31
93.38
96.38
45.53
48.29
59.58
79.15
80.00
38.28
41.66
47.25
75.00
87.50
100.00
35.69
46.40
74.11
88.42
100.00
42.85
100.00
100.00
100.00
The values in parentheses denoted percentage of increase growth over control.
—, no growth.
tion. Evaluation of the antifungal activities revealed that 4-aryl-
1,4-dihydropyridines 4a–f showed significant in vitro antifungal
activities against tested fungi with low MIC values in the range
References and notes
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0.025–0.35 lg/mL.
Acknowledgments
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O.M.S. is thankful to CSIR project (No. 01(2135)/07/EMR-II) for
financial assistance. We also thank SAIF, CDRI, Lucknow & SAIF,
NEHU, Shillong for the spectral recordings.

O. M. Singh et al. / Bioorg. Med. Chem. Lett. 18 (2008) 6462–6467
6467
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15. To a mixture of aldehyde 1 (10 mmol), b-dicarbonyl compound 2 (10 mmol)
and urea 3 (12 mmol), CuCl2ꢀ2H2O (2 mmol, 20 mol%) was added at room
temperature. After it was stirred for 5 min, the resulting mixture was heated at
100 °C in a preheated oil bath for 20 min–1 h (monitored by TLC). The reaction
mixture was brought to room temperature, crushed and 100 mL of cold water
was added and stirred for 5–10 min. The solid was filtered, washed with ice-
cold water (100 mL) and then recrystallized from hot ethanol to afford pure
product.
8.90 (br s, NH); IR (KBr): 3253, 1721, 1687 cmꢁ1. EIMS: m/z (%) 320 (M+), 292,
273, 247, 138, 97.
Compound 4l: 1H NMR (DMSO-d6): d 1.15 (t, J = 7.1 Hz, 3H), 2.30 (s, 3H), 4.00 (q,
J = 7.1 Hz, 2H), 5.35(s, 1H), 7.20–7.25 (m, 2H), 8.40–8.58 (m, 2H), 9.00 (br s, 1H,
NH), 9.40 (br s, NH); 13C NMR: d 13.7, 17.7, 49.6, 59.9, 106.4, 124.7, 124.8,
139.3, 146.6, 150.8, 156.8, 165.2; IR (KBr): 3290, 1712, 1679, 1589 cmꢁ1. EIMS:
m/z (%) 261 (M+), 233, 216. Anal. Calcd for C13H15N3O3: C, 59.76; H, 5.79; N,
16.08. Found: C, 59.70; H, 5.63; N, 16.28.
Compound 4m: 1H NMR (DMSO-d6): d 1.15 (t, J = 7.1 Hz, 3H), 2.35 (s, 3H), 4.10
(q, J = 7.1 Hz, 2H), 5.95 (s, 2H), 6.75–6.85 (m, 3H), 8.25 (br s, 1H, NH), 8.90 (br s,
NH); IR (KBr): 3353, 1701, 1647 cmꢁ1. EIMS: m/z (%) 304 (M+), 275, 258, 231,
183, 69.
Compound 4n: 1H NMR (DMSO-d6): d 0.95 (t, J = 7.1 Hz, 3H), 2.45 (s, 3H), 3.95
(q, J = 7.1 Hz, 2H), 5.25 (s, 1H), 6.91–7.20 (m, 2H), 7.45–7.60 (m, 2H), 7.85 (t,
J = 8.2 Hz, 1H), 7.95 (d, J = 8.2 Hz, 1H), 8.35 (d, J = 8.2 Hz, 1H), 9.15 (br s, NH); IR
(KBr): 3253, 1699, 1647, 1435 cmꢁ1. EIMS: m/z (%) 310 (M+), 217, 176, 231,
133, 69.
16. Massa, S.; Di Santo, R.; Retico, A.; Simonetti, N.; Fabrizi, G.; Lamba, D. Eur. J.
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17. (a) Pani, B. K.; Patra, A. K. Mush. Res. 1997, 6, 37; (b) Vidal, C.; Fargues, J.; Lacey,
L. A. J. Invert. Pathol. 1997, 70, 18; (c) Wraight, S. P.; Carruthers, R. I.; Bradley, C.
A.; Jaronskic, S. T.; Lacey, L. A.; Wood, P.; Galaini-Wraight, S. J. Invert. Pathol.
1998, 71, 217; (d) Wraight, S. P.; Carruthers, R. I.; Bradleyc, C. A.; Jaronski, S. T.;
Lacey, L. A.; Wood, P.; Galaini-Wraight, S. Biol. Control 2000, 17, 203.
18. Two hundred and fifty grams of peeled and sliced potatoes were washed in tap
water and boiled in 500 mL distilled water for 30 min or till it could be crushed
by a glass rod and the extract was filtered into a beaker (1000 mL) through a
muslin cloth. Twenty grams of dextrose was added to the extract and its
volume was made up to 1000 mL by adding additional distilled water to make
potato dextrose broth. Agar was dissolved to the potato dextrose broth. The
medium thus prepared was dispensed into conical flasks and sterilized in an
autoclave at 15l bs psi pressure for 20 min after wrapping the cotton plugs
with paper. This sterilized PDA medium was stored for further experiment.
19. (a) Vincent, J. M. Nature 1947, 96, 596; (b) Seth, P. K.; Bhardwaj, S. C. Indian J.
Mush. 1986, 12, 81; (c) Lopez-Herrera, C. J.; Zea-Bonilla, T. Crop Prot. 2007, 26,
1186.
5-(Ethoxycarbonyl)-6-methyl-4-phenyl-3,4-dihydropyrimidin-2(1H)-one 4a: 1H
NMR (DMSO-d6): d 1.17 (t, J = 7.1 Hz, 3H), 2.30 (s, 3H), 4.05 (q, J = 7.1 Hz,
2H), 5.25 (s, 1H), 7.19–7.35 (m, 6H), 8.98 (br s, 1H, NH); IR (KBr): 3242, 1721,
1637 cmꢁ1. EIMS: m/z (%) 260 (M+), 232, 184, 156, 138, 43. Anal. Calcd for
C14H16N2O3: C, 64.60; H, 6.20; N, 10.76. Found: C, 64.64; H, 6.25; N, 10.92.
Compound 4k: 1H NMR (DMSO-d6): d 1.15 (t, J = 7.1 Hz, 3H), 2.30 (s, 3H), 3.85 (s,
6H), 4.05 (q, J = 7.1 Hz, 2H), 5.25 (s, 1H), 6.80–6.85 (m, 3H), 7.25 (br s, 1H, NH),