Rapid and efficient synthesis of fused heterocyclic pyrimidines under ultrasonic irradiation

Article abstract of DOI:10.1016/j.ultsonch.2009.07.002

Some fused heterocyclic pyrimidines have been synthesized in high yields using ultrasound irradiation in a one-pot, three-component and efficient process by condensation reaction of barbituric acids, aldehydes and a series of enamines in water. Prominent among the advantages of this new method are operational simplicity, good yields in short reaction times and easy work-up procedures employed.

Full text of DOI:10.1016/j.ultsonch.2009.07.002

Ultrasonics Sonochemistry 17 (2010) 162–167
Contents lists available at ScienceDirect
Ultrasonics Sonochemistry
journal homepage: www.elsevier.com/locate/ultsonch
Rapid and efficient synthesis of fused heterocyclic pyrimidines under
ultrasonic irradiation
*
Mohammad Hossein Mosslemin , Mohammad Reza Nateghi
Department of Chemistry, Islamic Azad University, Yazd Branch, P.O. Box 89195-155, Yazd, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 22 April 2009
Received in revised form 28 June 2009
Accepted 16 July 2009
Available online 21 July 2009
Some fused heterocyclic pyrimidines have been synthesized in high yields using ultrasound irradiation in
a one-pot, three-component and efficient process by condensation reaction of barbituric acids, aldehydes
and a series of enamines in water. Prominent among the advantages of this new method are operational
simplicity, good yields in short reaction times and easy work-up procedures employed.
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
Uracil
Barbituric acid
Aldehyde
Pyrimidine
Ultrasound
1. Introduction
cyclic systems have attracted considerable attention in search for a
rapid entry to these heterocycles.
Recently published comprehensive books [1] and papers [2]
indicate chemical applications of ultrasounds. ‘‘Sonochemistry”,
is a new trend in organic chemistry, offering a versatile and facile
pathway for a large variety of syntheses. Thus, a large number of
organic reactions can be carried out under ultrasonic irradiation
in high yields, short reaction times and mild conditions [1–3].
Heterocycles containing a pyrimidine moiety are of interest be-
cause they constitute an important class of natural and non-natu-
ral products, many of which exhibit useful biological activities and
clinical applications [4]. Furthermore, the pyrimidopyrimidines are
an important class of annelated uracils with biological significance
because of their connection with purine pteridine system [5].
Numerous reports delineate the antitumor [6], antiviral [7], and
antioxidant [8] activity of these compounds. In addition, some
pyrimidine fused heterocyclic systems like furo [9], pyrazolo
[10], pyrrolo [11], pyridopyrazolo [12], and pyrazolotriazolo [13]
pyrimidine have long been important to the pharmaceutical indus-
try. Therefore, for the preparation of these complex molecules
large efforts have been directed towards the synthetic manipula-
tion of amino-uracils or amino-pyrazoles. As result, a number of re-
ports have appeared in literature, which usually requires forcing
conditions, long reaction times, and complex synthetic pathway
[14]. Thus new routes for the synthesis of pyrimidine fused hetero-
With the emphasis on the search for atom-efficient transforma-
tions of easily available starting materials into complex organic
molecules [15], reactions that provide maximum diversity are
especially desirable. Here, expeditious domino [16], and multi-
component reactions (MCRs) [17] have emerged as powerful
strategies. MCRs are economically and environmentally very
advantageous because multi-step syntheses produce considerable
amounts of waste mainly due to complex isolation procedures
often involving expensive, toxic and hazardous solvents after each
step.
Considering the above reports we wish to report a one-pot,
three-component condensation reaction of barbituric acids 1a–c,
aldehydes 2a–f and amino-uracils (3a,b) for the synthesis of some
fused heterocyclic pyrimidines in water under ultrasonic irradia-
tion (Scheme 1). In fact, as clearly stated by Sheldon, it is generally
recognized that ‘‘the best solvent is no solvent and if a solvent (dil-
uent) is needed it should preferably be water” [18].
2. Experimental
2.1. Chemicals and apparatus
The chemical used in this work were obtained from Fluka and
Merck, and amino-uracil was from Merck. 1,3-Diphenyl-1H-pyra-
zol-5-amine was prepared according to the literature procedure
[19]. Melting points were measured on an Electrothermal 9200
* Corresponding author. Fax: +98 351 8214813.
E-mail address: mosleminemh@yahoo.com (M.H. Mosslemin).
1350-4177/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.ultsonch.2009.07.002

M.H. Mosslemin, M.R. Nateghi / Ultrasonics Sonochemistry 17 (2010) 162–167
163
O
Ar
O
O
X
RN
NR1
H2O/ 60 oC
R1N
RN
NR
+
ArCHO
+
Piperidine
))))))
1 h
NH2
X
N
R
N
H
N
O
R1
O
N
O
O
R1
X=O, R=H 1a
X=O, R=Me 1b
X=S, R=H 1c
R1=Me 3a
R1=H 3b
2a-f
4a-l
Scheme 1.
apparatus. IR spectra were recorded on a FT-IR 102 MB BOMEM
apparatus. Mass spectra were recorded on a FINNIGAN-MAT
8430 mass spectrometer operating at an ionization potential of
70 eV. 1H and 13C NMR spectra were recorded on a BRUKER DRX-
300 AVANCE spectrometer at 300.13 and 75.47 MHz. 1H and 13C
NMR spectra were obtained on solutions in DMSO-d6 using TMS.
Ultrasonication was performed in a EUROSONICÒ 4D ultrasound
cleaner with a frequency of 50 kHz and an output power of
350 W. The reactions were performed in open vessels.
2.2.4. 1,3-Dimethyl-5-(4-methylphenyl)-9,10-dihydropyrido[2,3-d:6,
5-d]dipyrimidine-2,4,6,8(1H,3H,5H,7. H)-tetraone (4d)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3260, 3145,
1700, 1670; 1H NMR (300 MHz, DMSO-d6 dH (ppm) 2.31 (3H, s,
CH3), 3.05 (3H, s, CH3), 3.40 (3H, s, CH3), 4.72 (1H, s, CH), 6.69–
7.09 (4H, m, H–Ar), 8.94 (1H, s, NH), 10.08 (1H, bs, NH), 10.93
(1H, s, NH) 13C NMR (75 MHz, DMSO-d6): dC (ppm) 21.1, 28.3,
29.8, 34.1, 90.1, 90.3, 114.4, 120.5, 129.0, 143.1, 146.2, 148.9,
151.0, 159.6, 161.0, 162.6. MS (m/z): 367. Anal. Calcd. for
C18H17N5O4: C, 58.85; H, 4.66; N, 19.06%. Found: C, 58.89; H,
4.60; N, 19.0%.
2.2. General procedure
Solubility of the products 4e–j is very low and we can not report
the 13C NMR data for these products.
A mixture of barbituric acid (1 mmol), aromatic aldehyde
(1 mmol), enamine (1 mmol), and piperidine (0.5 mmol) in water
(5 mL) was sonicated at 60 °C for 1 h. The progress of the reaction
was monitored by TLC. After completion, the reaction mixture was
allowed to cool to room temperature. The solid was collected by fil-
tration and washed with ethanol (10 mL) to afford the pure
product.
2.2.5. 5-Phenyl-9,10-dihydropyrido[2,3-d:6,5-d]dipyrimidine-2,4,6,
8(1H,3H,5H,7H)-tetraone (4e)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3225, 3080,
1698, 1660. 1H NMR (300 MHz, DMSO-d6): dH 4.70 (1H, s, CH),
7.02–7.21 (5H, m, H–Ar), 9.97 (2H, s, 2NH), 10.90 (2H, s, 2NH).
MS (m/z): 326 (M++1). Anal. Calcd. for C15H11N5O4: C, 55.39; H,
3.41, N, 21.53%. Found: C, 55.44; H, 3.37; N, 21.46%.
2.2.1. 1,3-Dimethyl-5-phenyl-9,10-dihydropyrido[2,3-d:6,5-d]dipyri-
midine-2,4,6,8(1H,3H,5H,7H)-tetraone (4a)
2.2.6. 5-(4-Chlorophenyl)-9,10-dihydropyrido[2,3-d:6,5-d]dipyri-
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3320, 1715,
midine-2,4,6,8(1H,3H,5H,7H)-tetraone (4f)
1685; 1H NMR (300 MHz, DMSO-d6): dH 3.04 (3H, s, CH3), 3.40 (3H,
s, CH3), 4.72 (1H, s, CH), 7.12–7.29 (5H, m, H–Ar), 8.90 (1H, s, NH),
10.09 (1H, s, NH), 10.81 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6):
28.0, 30.2, 34.8, 90.4, 90.9, 126.0, 128.2, 143.4, 146.8, 149.9, 150.7,
160.0, 162.6. MS (m/z): 353 (M+). Anal. Calcd. for C17H15N5O4: C,
57.79; H, 4.28; N, 19.82%. Found: C, 57.85; H, 4.32; N, 19.75%.
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3261, 3200,
3012, 1711, 1700, 1685. 1H NMR (300 MHz, DMSO-d6): dH 4.60 (1H,
s, CH), 7.23–7.30 (4H, m, H–Ar), 10.80 (2H, s, 2NH), 11.12 (2H, s,
2NH). MS (m/z): 360 (M++1). Anal. Calcd. for C15H10ClN5O4: C,
50.08; H, 2.80; N, 19.47%. Found: C, 50.13; H, 2.74; N, 19.53%.
2.2.7. 5-(Thiophen-2-yl)-9,10-dihydropyrido[2,3-d:6,5-d]dipyri-
2.2.2. 1,3-Dimethyl-5-(4-chlorophenyl)-9,10-dihydropyrido[2,3-d:6,5-
midine-2,4,6,8(1H,3H,5H,7H)-tetraone (4g)
Brown powder; 168 °C dec.; IR (KBr) (m
max, cmꢀ1): 3320, 3165,
d]dipyrimidine-2,4,6,8(1H,3H,5H,7H)-tetraone (4b)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3389, 3188,
3056,1732, 1676, 1655. 1H NMR (300 MHz, DMSO-d6): dH 4.91
(1H, s, CH), 7.50 (1H, m, thienyl), 7.98 (1H, d, 3JHH = 4.3 Hz, thienyl),
1698; 1H NMR (300 MHz, DMSO-d6): dH 3.03 (3H, s, CH3), 3.30 (3H,
s, CH3), 4.79 (1H, s, CH), 7.09–7.30 (4H, m, H–Ar), 8.90 (1H, s, NH),
10.10 (H, s, NH), 10.88 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6):
28.3, 30.9, 34.0, 91.0, 91.9, 127.5, 128.7, 142.6, 147.2, 148.8,
152.7, 161.4, 162.9. MS (m/z): 387 (M+). Anal. Calcd. for
C17H14ClN5O4: C, 52.65; H, 3.64; N, 18.06%. Found: C, 52.60; H,
3.60; N, 18.13%.
3
8.08 (1H, d, JHH = 4.1 Hz, thienyl), 9.99 (2H, s, 2NH), 10.95 (2H, s,
2NH). MS (m/z): 331 (M+). Anal. Calcd. for C13H9N5O4S: C, 47.13;
H, 2.74, N, 21.14%. Found: C, 47.19; H, 2.70; N, 21.08%.
2.2.8. 5-(Furyl-2-yl)-9,10-dihydropyrido[2,3-d:6,5-d]dipyrimidine-
2,4,6,8(1H,3H,5H,7H)-tetraone (4h)
Red powder; 160 °C dec.; IR (KBr) (m
max, cmꢀ1): 3332, 3175,
3076, 1728, 1698, 1659. 1H NMR (300 MHz, DMSO-d6): dH 4.98
2.2.3. 1,3-Dimethyl-5-(4-nitrophenyl)-9,10-dihydropyrido[2,3-d:6,5-
3
(1H, s, CH), 7.53 (1H, m, furyl), 7.97 (1H, d, JHH = 4.1 Hz, furyl),
d]dipyrimidine-2,4,6,8(1H,3H,5H,7H)-tetraone (4c)
3
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3360, 1688;
8.18 (1H, d, JHH = 4.2 Hz, furyl), 10.02 (2H, s, 2NH), 10.97 (2H, s,
2NH). MS (m/z): 315 (M+). Anal. Calcd. for C13H9N5O5: C, 49.53;
1H NMR (300 MHz, DMSO-d6): dH 3.08 (3H, s, CH3), 3.45 (3H, s,
3
H, 2.88, N, 22.22%. Found: C, 49.45; H, 2.82; N, 22.31%.
CH3), 4.91 (1H, s, CH), 7.54 (2H, d, JHH = 9.0 Hz, H–Ar), 8.06 (2H,
3
d, JHH = 8.9 Hz, H–Ar), 9.01 (1H, s, NH), 10.09 (1H, s, NH), 10.90
(1H, s, NH). 13C NMR (75 MHz, DMSO-d6): 28.0, 30.0, 35.2, 88.5,
89.0, 123.1, 128.3, 129.4, 146.4, 149.4, 150.9, 153.8, 154.5, 160.9,
162.0. MS (m/z): 398 (M+). Anal. Calcd. for C17H14N6O6: C, 51.26;
H, 3.54; N, 21.10%. Found: C, 51.29; H, 3.50; N, 21.05%.
2.2.9. 5-Phenyl-8-thioxo-9,10-dihydropyrido[2,3-d:6,5-d]dipyri-
midine-2,4,6(1H,3H,5H,7H)-trione (4i)
Yellow powder; m.p. > 300 °C. IR (KBr) (
1696, 1678. 1H NMR (300 MHz, DMSO-d6): dH 4.78 (1H, s, CH),
m
max, cmꢀ1): 3270, 3065,

164
M.H. Mosslemin, M.R. Nateghi / Ultrasonics Sonochemistry 17 (2010) 162–167
7.13–7.19 (5H, m, H–Ar), 9.06 (1H, s, NH), 9.72 (1H, s, NH), 10.78
(1H, s, NH), 12.40 (1H, s, NH). MS (m/z): 341 (M+). Anal. Calcd.
for C15H11N5O3S: C, 52.78; H, 3.25; N, 20.52%. Found: C, 52.82; H,
3.20; N, 20.59%.
s, NH), 10.83 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 21.3,
26.4, 28.8, 32.3, 33.8, 39.4, 50.2, 96.7, 118.2, 125.1, 127.0, 129.1,
145.9, 148.5, 154.0, 160.0, 162.1, 192.1. MS (m/z): 351 (M+). Anal.
Calcd. for C20H21N3O3: C, 68.36; H, 6.02; N, 11.96%. Found: C,
68.30; H, 5.97; N, 11.89%.
2.2.10. 5-(4-Chlorophenyl)-8-thioxo-9,10-dihydropyrido[2,3-d:6,5-d]-
dipyrimidine-2,4,6(1H,3H,5H,7H)-trione (4j)
2.2.16. 1,3,8,8-Tetramethyl-5-phenyl-7,8,9,10-tetrahydro-
Yellow powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3255,
pyrimido[4,5-b]quinoline-2,4,6(1H,3H,5H)-trione (6d)
3050, 1711, 1648. 1H NMR (300 MHz, DMSO-d6): dH (ppm) 4.61
(1H, s, CH), 722–7.25 (4H, m, H–Ar), 9.01 (1H, s, NH), 9.73 (1H, s,
NH), 10.72 (1H, s, NH), 11.70 (1H, s, NH). MS (m/z): 375 (M+). Anal.
Calcd. for C15H10ClN5O3S: C, 47.94; H, 2.68; N,18.64%. Found: C,
48.0; H, 2.71; N, 18.69%.
White powder; m.p. 268 °C (dec.); IR (KBr) (m
max, cmꢀ1): 3222,
1700, 1673, 1679. 1H NMR (300 MHz, DMSO-d6): dH 1.0 (3H, s,
CH3), 1.02 (3H, s, CH3), 2.45 (2H, s, CH2), 2.56 (2H, s, CH), 3.03
(3H, s, CH3), 3.41 (3H, s, CH3), 4.91 (1H, s, CH), 7.21–7.26 (5H, m,
H–Ar). 8.93 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.6,
28.4, 28.8, 31.3, 32.2, 33.3, 39.7, 50.4, 96.0, 119.0, 125.2, 127.4,
129.0, 146.4, 148.0, 154.3, 160.1, 162.0, 192.5. MS (m/z): 365
(M+). Anal. Calcd. for C21H23N3O3: C, 69.02; H, 6.34; N, 11.50%.
Found: C, 69.06; H, 6.29; N, 11.56%.
2.2.11. 1,3-Dimethyl-5-phenyl-8-thioxo-9,10-dihydropyrido[2,3-d:6,
5-d]dipyrimidine-2,4,6(1H,3H,5H,7H)-trione (4k)
Cream powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3234, 3178,
1698, 1689. 1H NMR (300 MHz, DMSO-d6): 3.07 (3H, s, CH3), 3.40
(3H, s, CH3), 4.67 (1H, s, CH), 7.10–7.28 (5H, m, H–Ar), 8.97 (1H,
s, NH), 11.78 (1H, s, NH), 12.30 (1H, s, NH). 13C NMR (75 MHz,
DMSO-d6): dC 28.3, 30.0, 34.4, 89.7, 94.8, 125.8, 128.3, 128.7,
143.0, 144.6, 150.2, 160.1, 160.9, 172.6. MS (m/z): 369. Anal. Calcd.
for C17H15N5O3S: C, 55.27; H, 4.09; N, 18.96%. Found: C, 55.22; H,
4.05; N, 18.89%.
2.2.17. 5-(4-Chlorophenyl)-1,3,8,8-tetramethyl-7,8,9,10-tetrahydro-
pyrimido[4,5-b]quinoline-2,4,6(1H,3H,5H)-trione (6e)
White powder; m.p. 291 °C (dec.) (lit., [20] m.p. 292 °C); IR (KBr)
(m
max, cmꢀ1): 3330, 1703, 1691, 1688. 1H NMR (300 MHz, DMSO-
d6): dH 1.03 (6H, s, 2CH3), 2.42 (2H, s, CH2), 2.50 (2H, s, CH), 3.02
(3H, s, CH3), 3.41 (3H, s, CH3), 4.89 (1H, s, CH), 7.24–7.26 (4H, m,
H–Ar). 8.98 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.4,
28.7, 28.9, 31.5, 32.1, 33.4, 39.9, 50.9, 96.9, 119.6, 127.4, 128.9,
129.1, 146.4, 148.2, 154.7, 160.2, 162.5, 192.2. MS (m/z): 399
(M+). Anal. Calcd. for C21H22ClN3O3: C, 63.08; H, 5.55; N, 10.51%.
Found: C, 63.02; H, 5.59; N, 10.59%.
2.2.12. 1,3-Dimethyl-5-(4-chlorophenyl)-8-thioxo-9,10-dihydro-
pyrido[2,3-d:6,5-d]dipyrimidine-2,4,6(1H,3H, 5H,7H)-trione (4l)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3240, 1697,
1662. 1H NMR (300 MHz, DMSO-d6): dH 3.08 (3H, s, CH3), 3.41 (3H,
s, CH3), 4.76 (1H, s, CH), 7.20–7.27 (4H, m, H–Ar). 9.07 (1H, s, NH),
11.43 (1H, s, NH), 12.30 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6):
dC 28.1, 30.4, 34.3, 89.9, 95.1, 125.9, 128.0, 128.6, 143.2, 144.5,
151.2, 162.1, 163.7, 172.8. MS (m/z): 404 (M++1). Anal. Calcd. for
C17H14ClN5O3S: C, 50.56; H, 3.49; N, 17.34%. Found: C, 50.50; H,
4.54; N, 17.26%.
2.2.18. 8,8-Dimethyl-5-phenyl-2-thioxo-2,3,7,8,9,10-hexahydro-
pyrimido[4,5-b]quinoline-4,6(1H,5H)-dione (6f)
Cream powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3311, 3109,
1703, 1669. 1H NMR (300 MHz, DMSO-d6): dH 0.99 (3H, s, CH3),
1.04 (3H, s, CH3), 2.46 (2H, s, CH2), 2.56 (2H, s, CH), 4.89 (1H, s,
CH), 7.24–7.28 (5H, m, H–Ar). 8.99 (1H, s, NH), 10.06 (1H, s, NH),
12.46 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.5, 28.7,
32.4, 33.6, 39.8, 50.7, 89.4, 119.0, 125.6, 127.6, 129.0, 146.6,
148.9, 154.3, 161.2, 169.8, 192.7. MS (m/z): 353 (M+). Anal. Calcd.
for C19H19N3O2S: C, 64.57; H, 5.42; N, 11.89%. Found: C, 64.51; H,
5.47; N, 11.80%.
2.2.13. 8,8-Dimethyl-5-phenyl-7,8,9,10-tetrahydropyrimido[4,5-b]-
quinoline-2,4,6(1H,3H,5H)-trione (6a)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3336, 1708,
1665. 1H NMR (300 MHz, DMSO-d6): dH 0.94 (3H, s, CH3), 1.02 (3H,
s, CH3), 2.47 (2H, s, CH2), 2.56 (2H, s, CH), 4.86 (1H, s, CH), 7.20–
7.24 (5H, m, H–Ar). 8.91 (1H, s, NH), 10.08 (1H, s, NH), 10.82
(1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.6, 28.8, 32.3,
33.5, 39.9, 50.2, 96.3, 118.3, 125.5, 127.4, 129.3, 146.7, 148.4,
154.1, 160.2, 162.3, 192.7. MS (m/z): 337 (M+). Anal. Calcd. for
C19H19N3O3: C, 67.64; H, 5.68; N, 12.46%. Found: C, 67.69; H,
5.64; N, 12.40%.
2.2.19. 5-(4-Chlorophenyl)-8,8-dimethyl-2-thioxo-2,3,7,8,9,10-hexa-
hydropyrimido[4,5-b]quinoline-4,6(1H,5H)-dione (6g)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3331, 3114,
1711, 1673, 1645. 1H NMR (300 MHz, DMSO-d6): dH 0.98 (3H, s,
CH3), 1.03 (3H, s, CH3), 2.47 (2H, s, CH2), 2.52 (2H, s, CH), 4.91
(1H, s, CH), 7.26–7.29 (4H, m, H–Ar). 8.98 (1H, s, NH), 10.09 (1H,
s, NH), 12.53 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.6,
28.4, 32.8, 33.6, 39.7, 50.5, 89.1, 119.3, 126.6, 127.9, 129.4, 146.0,
148.7, 154.6, 161.5, 171.0, 192.8. MS (m/z): 387 (M+). Anal. Calcd.
for C19H18ClN3O2S: C, 58.83; H, 4.68; N, 10.83%. Found: C, 58.88;
H, 4.64; N, 10.90%.
2.2.14. 5-(4-Chlorophenyl)-8,8-dimethyl-7,8,9,10-tetrahydro-
pyrimido[4,5-b]quinoline-2,4,6(1H,3H,5H)-trione (6b)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3345, 1708,
1673. 1H NMR (300 MHz, DMSO-d6): dH 0.94 (3H, s, CH3), 1.01 (3H,
s, CH3), 2.47 (2H, s, CH2), 2.57 (2H, s, CH), 4.92 (1H, s, CH), 7.22–
7.26 (4H, m, H–Ar). 8.93 (1H, s, NH), 10.07 (1H, s, NH), 10.84
(1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 26.7, 28.7, 32.4,
33.6, 39.8, 50.5, 96.4, 118.6, 127.5, 129.4, 130.3, 145.7, 148.4,
154.5, 160.3, 162.8, 192.7. MS (m/z): 371 (M+). Anal. Calcd. for
C19H18ClN3O3: C, 61.38; H, 4.88; N, 11.30%. Found: C, 61.42; H,
4.92; N, 11.25%.
2.2.20. 1,3,4-Triphenyl-4,9-dihydro-1H-pyrazolo[40,30:5,6]pyrido[2,
3-d]pyrimidine-5,7(6H,8H)-dione (8a)
White powder; m.p. 295 °C (dec.); IR (KBr) (m
max, cmꢀ1): 3223,
3089, 1698, 16671H NMR (300 MHz, DMSO-d6): dH 5.30 (1H, s,
CH), 7.07–7.46 (15H, m, H–Ar), 9.11 (1H, s, NH), 10.01 (1H, s,
NH), 10.78 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 35.1,
90.1, 102.3, 123.5, 126.0, 127.2, 128.6, 128.2, 130.1, 133.4, 136.9,
138.6, 145.5, 146.0, 147.9, 150.7, 163.8. MS (m/z): 433 (M+). Anal.
Calcd for C26H19N5O2: C, 72.04; H, 4.42; N, 16.16%. Found: C,
72.00; H, 4.36; N, 16.22%.
2.2.15. 8,8-Dimethyl-5-p-tolyl-7,8,9,10-tetrahydropyrimido[4,5-b]-
quinoline-2,4,6(1H,3H,5H)-trione (6c)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3340, 1699,
1670. 1H NMR (300 MHz, DMSO-d6): dH 0.99 (3H, s, CH3), 1.01 (3H,
s, CH3), 2.32 (3H, s, CH3), 2.44 (2H, s, CH2), 2.56 (2H, s, CH), 4.87
(1H, s, CH), 7.22–7.25 (4H, m, H–Ar). 8.90 (1H, s, NH), 10.06 (1H,

M.H. Mosslemin, M.R. Nateghi / Ultrasonics Sonochemistry 17 (2010) 162–167
165
2.2.21. 4-(4-Chlorophenyl)-1,3-diphenyl-4,9-dihydro-1H-pyra-
zolo[40,30:5,6]pyrido[2,3-d]pyrimidine-5,7. (6H,8H)-dione (8b)
White powder; m.p. > 300 °C; IR (KBr) (
max, cmꢀ1): 3234, 3089,
3. Results and discussion
m
To achieve suitable conditions for the synthesis of fused hetero-
cyclic pyrimidines, we investigated the reaction of barbituric acid
1a, benzaldehyde 2a and 6-amino-uracil 3a in different conditions.
In refluxing various solvent or under solvent-free conditions, the
reaction was very slow and the yield of product was very low.
We found that the best results were obtained in the presence of
piperidine under ultrasound irradiation at 60 °C in water (Table
1). As indicated in Table 1, ultrasonic irradiation (Table 1, entry
6) relative to refluxing water (Table 1, entry 4) induces acceleration
for reaction, the reaction time decreases from 6 h to 1 h. Also, un-
der ultrasonic irradiation the yield of product is higher. In absence
of piperidine under ultrasonic irradiation at 60 °C yield was found
to be low even after 3 h (Table 1, entry 7). Table 1 demonstrates
that water was the best choice of solvent and the use of ultrasound
radiation in water improves the rate of the reaction and also the
yield of the product. To study the effect of temperature on this syn-
thesis, we also performed three experiments in 40, 50, and 60 °C
under sonication (Table 1). It was observed that a lower reaction
temperature leads to a lower yield.
1704, 1639. 1H NMR (300 MHz, DMSO-d6): dH 5.31 (1H, s, CH),
7.14–7.67 (14H, m, H–Ar), 9.11 (1H, s, NH), 10.05 (1H, s, NH),
10.72 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 35.8, 89.7,
101.0, 123.1, 127.5, 128.1, 128.8, 128.2, 130.5, 131.4, 133.1,
137.4, 137.9, 145.2, 145.0, 147.2, 150.4, 163.7. MS (m/z): 467
(M+). Anal. Calcd for C26H18ClN5O2: C, 66.74; H, 3.88; N, 14.97%.
Found: C, 66.66; H, 3.84; N, 15.03%.
2.2.22. 4-(4-Methylphenyl)-1,3-diphenyl-4,9-dihydro-1H-pyra-
zolo[40,30:5,6]pyrido[2,3-d]pyrimidine-5,7. (6H,8H)-dione (8c)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3226, 3032,
1718, 1643. 1H NMR (300 MHz, DMSO-d6): dH 2.11 (3H, s, CH3),
5.30 (1H, s, CH), 704–7.70 (14H, m, H–Ar), 9.03 (1H, s, NH), 9.99
(1H, s, NH), 10.70 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC
21.2, 35.6, 89.7, 102.0, 123.1, 127.4, 128.0, 128.1, 128.4, 128.7,
130.1, 133.7, 135.0, 137.8, 138.5, 143.2, 145.5, 147.4, 150.5,
163.1. MS (m/z): 447 (M+). Anal. Calcd for C27H21N5O2: C, 72.47;
H, 4.73; N, 15.65%. Found: C, 72.52; H, 4.68; N, 15.60%.
To explore the scope and limitation of this reaction, we have ex-
tended the reaction of barbituric acids (1a–c) with a range of aro-
matic or heteroaromatic aldehydes (2a–f) and uracils (3a,b) under
2.2.23. 5,8-Dimethyl-1,3,4-triphenyl-4,9-dihydro-1H-pyra-
zolo[40,30:5,6]pyrido[2,3-d]pyrimidine-5,7(6H,8H)-dione (8d)
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3210, 1714,
1632. 1H NMR (300 MHz, DMSO-d6): dH 3.01 (3H, s, CH3), 3.43 (3H,
s, CH3), 5.31 (1H, s, CH), 7.11–7.77 (15H, m, H–Ar), 9.01 (1H, s, NH).
13C NMR (75 MHz, DMSO-d6): dC 28.6, 31.4, 35.5, 90.5, 102.5, 123.6,
127.2, 128.0, 128.1, 128.9, 129.7, 130.6, 133.6, 135.2, 137.6, 138.0,
143.4, 145.1, 147.7, 150.3, 163.4. MS (m/z): 461 (M+). Anal. Calcd.
for C28H23N5O2: C, 72.87; H, 5.02; N, 15.17%. Found: C, 72.81; H,
5.06; N, 15.10%.
Table 1
Conditions effect on reactiona.
Entry
Conditions
Catalyst
Time (h)
Yields (%)
1
2
3
4
5
6
7
8
CH3CN (Reflux)
EtOH (Reflux)
DMF (Reflux)
H2O (Reflux)
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
12
12
12
6
12
1
3
1
1
1
<40
<40
54
71
50
87
56
71
55
77
65
69
<40
75
56
Solvent-free/100 °C
H2O/60 °C/Ultrasound
H2O/60 °C/Ultrasound
H2O/50 oC/Ultrasound
H2O/40 °C/Ultrasound
H2O/60 °C/Ultrasound
H2O/60 °C/Ultrasound
H2O/60 °C/Ultrasound
H2O/60 °C/Ultrasound
EtOH/60 °C/Ultrasound
CH3CN/60 °C/Ultrasound
2.2.24. 4-(4-Chlorophenyl)-5,8-dimethyl-1,3-diphenyl-4,9-dihydro-
1H-pyrazolo[40,30:5,6]pyrido[2,3-d]pyrimidine-5,7(6H,8H)-dione (8e)
b
–
White powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3231, 1721,
Piperidine
Piperidine
Et3N
Na2CO3
K2CO3
KOH
Piperidine
Piperidine
1631. 1H NMR (300 MHz, DMSO-d6): dH 3.03 (3H, s, CH3), 3.40 (3H,
s, CH3), 5.34 (1H, s, CH), 7.16–7.79 (14H, m, H–Ar), 9.11 (1H, s, NH).
13C NMR (75 MHz, DMSO-d6): dC 28.7, 31.4, 35.7, 90.0, 102.6, 123.9,
127.6, 128.3, 128.6, 128.9, 129.6, 130.5, 133.8, 135.0, 137.5, 138.1,
143.3, 145.4, 147.9, 150.8, 163.9. MS (m/z): 495 (M+). Anal. Calcd.
for C28H22ClN5O2: C, 67.81; H, 4.47; N, 14.12%. Found: C, 67.76;
H, 4.51; N, 14.17%.
9
10
11
12
13
14
15
1
1
1
1
1
a
Barbituric acids (1 mmol), benzaldehyde (1 mmol), 6-amino-uracil (1 mmol),
Cat. (0.5 mmol).
b
In the absence of catalyst.
2.2.25. 1,3,4-Triphenyl-5-thioxo-1,4,5,6,8,9-hexahydro-7H-pyrazolo-
[40,30:5,6]pyrido[2,3-d]pyrimidine-7-dione (8f)
Cream powder; m.p. 258 °C (dec.); IR (KBr) (m
max, cmꢀ1): 3256,
3180, 1709, 1677. 1H NMR (300 MHz, DMSO-d6): dH 5.39 (1H, s,
CH), 7.07–7.70 (15H, m, H–Ar), 9.21 (1H, s, NH), 10.17 (1H, s,
NH), 10.77 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 35.9,
90.5, 102.7, 123.4, 127.2, 128.4, 128.6, 129.9, 130.2, 131.6, 133.8,
135.0, 137.2, 138.0, 143.1, 145.6, 147.7, 150.6, 163.3. MS (m/z):
449 (M+). Anal. Calcd. for C26H19N5OS: C, 69.47; H, 4.26; N,
15.58%. Found: C, 69.40; H, 4.33; N, 15.50%.
Table 2
Preparation of pyrido[2,3-d:6,5-d]dipyrimidines.
Product 4
R
R1
Ar
X
Yield (%)a
a
b
c
d
a
b
c
d
e
f
g
h
i
j
k
l
H
H
H
H
Me
Me
Me
Me
H
Me
Me
Me
Me
H
H
H
H
H
C6H5
O
O
O
O
O
O
O
O
O
O
O
O
S
85
87
85
81
86
89
90
91
87
88
81
78
91
88
90
87
4-Cl–C6H4
4-NO2–C6H4
4-Me–C6H4
C6H5
4-Cl–C6H4
4-NO2–C6H4
4-Me–C6H4
C6H5
4-Cl–C6H4
Thiophen-2-yl
Furan-2-yl
C6H5
4-Cl–C6H4
C6H5
2.2.26. 4-(4-Chlorophenyl)-1,3-diphenyl-5-thioxo-1,4,5,6,8,9-hexa-
hydro-7H-pyrazolo[40,30:5,6]pyrido[2,3-d]pyrimidine-7-dione (8g)
Cream powder; m.p. > 300 °C; IR (KBr) (m
max, cmꢀ1): 3250, 3171,
H
H
1700, 1667. 1H NMR (300 MHz, DMSO-d6): dH 5.34 (1H, s, CH),
7.16–7.76 (14H, m, H–Ar), 9.25 (1H, s, NH), 10.21 (1H, s, NH),
10.81 (1H, s, NH). 13C NMR (75 MHz, DMSO-d6): dC 35.8, 91.0,
102.3, 123.8, 127.5, 128.3, 128.7, 129.3, 130.0, 131.9, 132.9,
135.2, 137.0, 138.4, 143.5, 145.9, 147.4, 150.1, 163.6. MS (m/z):
483 (M+). Anal. Calcd. for C26H18ClN5OS: C, 64.52; H, 3.75; N,
14.47%. Found: C, 64.56; H, 3.70; N, 14.53%.
H
H
H
H
H
H
H
H
S
S
S
H
H
Me
H
4-Cl–C6H4
a
Isolated yields.

166
M.H. Mosslemin, M.R. Nateghi / Ultrasonics Sonochemistry 17 (2010) 162–167
O
Ar
O
O
X
RN
H2O/ 60 o
C
RN
NR
+
ArCHO
+
Piperidine
))))))
NH2
X
N
R
N
H
1 h
O
O
1
2
5
6a-g
Product 6
R
H
H
H
Me
Me
H
Ar
C6H5
4-Cl-C6H4
4-Me-C6H4
C6H5
4-Cl-C6H4
C6H5
X
Yield (%)
a
b
c
d
e
f
O
O
O
O
O
S
82
83
81
83
84
78
g
H
4-Cl-C6H4
S
80
Scheme 2.
O
Ar
X
Ph
N
Ph
H2O/ 60 oC
RN
RN
NR
+
Piperidine
))))))
ArCHO
+
N
NH2
1 h
N
N
X
N
R
N
H
O
O
Ph
Ph
1
2
7
8a-g
Product 8
R
Ar
X
Yield (%)
M.P. (oC)
Found Reported
a
b
c
d
e
f
H
H
H
Me
Me
H
C6H5
4-Cl-C6H4
4-Me-C6H4
C6H5
4-Cl-C6H4
C6H5
O
O
O
O
O
S
86
85
87
83
86
81
295 (dec.) 297 (dec.)21
>300
>300
320 (dec.)21
314 (dec.)21
>300
>300
258 (dec.)
-
-
-
g
H
4-Cl-C6H4
S
83
>300
-
Scheme 3.
X
RN
NR
O
Ar
X
X
O
O
RN
-H2O
NH2
RN
Ar
NR
NH2
RN
NR
ArCHO
Ar
X
N
R
N
H
O
O
O
O
9
Scheme 4.
similar conditions (H2O/60 °C/Ultrasound/piperidine), furnishing
the respective pyrido[2,3-d:6,5-d]dipyrimidines (4a–l) in good
yields (Scheme 1). The optimized results are summarized in Table
2. The results were excellent in terms of yields and product purity
using aromatic aldehydes carrying electron-donating or electron-
withdrawing substituents. Under the same conditions, with ali-
phatic aldehydes the yields of the reaction notably decreased
(i.e., 20%, with butanal or hexanal), probably due to the possible al-
dol condensation side reaction.
As expected, when the uracils (3) was replaced by 3-amino-5,5-
dimethylcyclohex-2-enone (5), another series of fused heterocyclic
pyrimidines, tetrahydropyrimido[4,5-b]quinolines (6), were ob-
tained in good yields under the same reaction conditions (Scheme
2).

M.H. Mosslemin, M.R. Nateghi / Ultrasonics Sonochemistry 17 (2010) 162–167
167
(c) K.S. Suslick, Sonochemistry in Comprehensive Coordination Chemistry, vol.
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217;
Recently, Bazgir et al. reported the synthesis of pyrazolo-
[40,30:5,6]pyrido[2,3-d]pyrimidine-diones (8) under solvent-free
conditions at 100 °C for 4 h [21]. Therefore, when 1,3-diphenyl-
1H-pyrazol-5-amine (7) was selected as enamine, the pyrazol-
o[40,30:5,6]pyrido[2,3-d]pyrimidine-dione derivatives 8 produced
in good yields for 1 h under ultrasound irradiation (Scheme 3).
The formation of pyrimidine derivatives (4), (6) and (8), can be
explained by the tentative mechanism presented in Scheme 4. The
Knoevenagel condensation product (9) reacted with enamine to
give the corresponding product.
(b) K. Jadidi, R. Gharemanzadeh, M. Mehrdad, H.R. Darabi, H.R. Khavasi, D.
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70;
(d) K.M. Al-Zaydi, Ultrason. Sonochem. 16 (2009) 805.
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Chemistry, vol. 13, Pergamon Press, Oxford, 1984, p. p. 57;
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The nature of these compounds as 1:1:1 adducts was apparent
from their mass spectra, which displayed, in each case, the molec-
ular ion peak at appropriate m/z values. Compounds (4), (6) and (8),
are stable solids whose structures are fully supported by IR, 1H and
13C NMR spectroscopy, mass spectrometry, and elemental analysis.
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4. Conclusion
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G.J. Cutler, L. Kane-Carson, W. Liu, D.K. Jung, Bioorg. Med. Chem. Lett. 15
(2005) 3778.
In conclusion, we have developed a simple, efficient and green
protocol for the synthesis of pyrimidine derivatives by a one-pot
and three-component reaction under ultrasound irradiation in
water. The simple work-up in isolation of the products in good
yields with high purity, mild reaction conditions, high atom econ-
omy of the reaction are features of this new procedure.
[13] P.G. Baraldi, H. El-Kashef, A.R. Farghaly, P. Vanellec, F. Fruttaroloa, Tetrahedron
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Acknowledgements
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We gratefully acknowledge the financial support from the Re-
search Council of Islamic Azad University, Yazd Branch.
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