Gypsum-catalyzed one-pot synthesis of 3,4-Dihydropyrimidin-2(1H)-ones under solvent-free conditions

Article abstract of DOI:10.1155/2011/780271

In view of the emerging importance of the green chemistry principles in chemical and pharmaceutical industries, we disclose, herein, a new economic approach producing the biologically active dihydropyrimidinones in good yields using the solventless one-po

Full text of DOI:10.1155/2011/780271

ISSN: 0973-4945; CODEN ECJHAO
E-Journal of Chemistry
2011, 8(1), 312-318
http://www.e-journals.net
Gypsum-Catalyzed One-Pot Synthesis of
3,4-Dihydropyrimidin-2(1H)-ones
Under Solvent-Free Conditions
TAOUES BOUMOUD§*, BOUDJEMAA BOUMOUD§,
PAUL MOSSET# and ABDELMADJID DEBACHE§
§Laboratoire des Produits Naturels d’origine Végétale et de Synthèse
Organique. Département de Chimie. Faculté des Sciences
Université Mentouri de Constantine 25000 Constantine, Algérie
#ENSChimie de Rennes,CNRS,UMR 6226, Avenue Gal Leclerc
CS 50837, 35708 Rennes Cedex 7, France
ta_boumoud@yahoo.fr
Received 23 April 2010; Accepted 17 June 2010
Abstract: In view of the emerging importance of the green chemistry
principles in chemical and pharmaceutical industries, we disclose, herein,
a
new economic approach producing the biologically active
dihydropyrimidinones in good yields using the solventless one-pot
Biginelli condensation in the presence of gypsum as an environmental
friendly and recycled catalyst.
Keywords: 3,4-Dihydropyrimidin-2(1H)-ones, Solvent-free reactions, Gypsum, MCCs.
Introduction
Due to environmental awareness, the development of simple, efficient and environmentally
benign chemical processes or methodologies for the synthesis of complex structures are the
major challenges for chemists’ world over1. The one-pot multi-component condensations
(MCCs) represent a possible instrument to perform a near ideal synthesis because they
possess several qualities, namely the possibility of building-up complex molecules with
maximum simplicity and brevity. Therefore, in recent years2, MCCs have attracted
considerable interest and have been transformed into one of the most efficient, economic and
environmentally friendly tools for combinatorial and parallel synthesis3.
Today, the one-pot Biginelli reaction, first described more than a century ago4, is
considered as one of the most important multi-component reactions for generating complex
compounds that possess diverse therapeutic and pharmacological properties4-6, therefore, their

Gypsum-catalyzed One-Pot Synthesis
313
synthesis has been the focus of much interest for organic and medicinal chemists. Thus,
several improved synthetic methods have been reported using Lewis acids as well as protic
acids as promoters under classical reflux7-13 or solvent free conditions14-20 and microwave21-24
or ultrasonic irradiation25.
Due to the ever-mounting environmental concern in the field of chemistry, it is
advisable to easily recover and recycle catalysts, especially toxic metallic ones.
Additionally, the challenge for a sustainable environment calls for clean procedures to avoid
harmful organic solvents.26 However, a number of the reported protocols for Biginelli
reaction use volatile toxic organic solvents, as reaction media and many heavy and
unrecovered metallic salts as catalysts which are not acceptable in the context of green
synthesis as they result in the pollution to environment to some extent. Therefore, there is
still room for further searches for better catalysts that could be superior to the existing ones
with regard to toxicity, handling and recyclability. In this respect, we are interested to
introduce potential catalyst to overcome these limitations.
In pursuit of developing a methodology for the preparation of these biologically
important compounds27-29,we herein describe a mild and efficient synthesis of dihydropyrimidinones,
via the solventless one-pot Biginelli condensation protocol, using gypsum, a mineral
composed of calcium sulfate with two molecules of water, as a recyclable, non toxic, easy
available and potential Lewis acid catalyst (Scheme 1).
R
R1
R
H
O
1
O
calcium sulfate dihydrate
(15mol%)
O
NH
NH2
+
R1
H3C
N
H
O
H2N
O
O
H3C
3
2
4
Scheme 1
Experimental
Unless specified all solvents and reagents were of reagent grade and used without further
purification. Melting points were determined in a capillary tube and are uncorrected. 1H and
13C NMR spectra were recorded as solutions in DMSO-d6 and chemical shifts are reported in
parts per million (ppm) on a BRUKER AVANCE DPX spectrometer at 250 and 62.9 MHz
respectively using TMS as internal standard. Spectral patterns are designated as s, singlet; d,
doublet; dd, double doublet; t, triplet; br, broad, m, multiplet. Coupling constants are
reported in hertz (Hz). IR spectra were obtained as potassium bromide (KBr) pellets with a
Shimadzu FT IR-8201 PC spectrometer.
General procedure for the synthesis of 3,4-dihydropyrimidinones (4)
In a typical experiment, a mixture of aldehyde (5 mmol, 535 mg), urea (5 mmol, 300 mg),
1,3-dicarbonyl compound (5 mmol, 650 mg) and CaSO4.2H2O (15 mol%), was heated with
stirring at 100 °C for the required time (Table 2) in a water bath. The reaction was
monitored by TLC using ethyl acetate/hexane (4/6). After completion (100% conversion
using aldehyde as the blank reactant), the resulting solidified mixture was diluted with hot
EtOH (20 mL). The resulting suspension was filtered through a Büchner funnel to recover
the catalyst and the filtrate was poured into ice cold water (30 mL). The resulting precipitate
was collected and recrystallized in EtOH to give the pure product 4. The recovered catalyst
dried for investigation of the recyclability of the catalyst.

314
TAOUES BOUMOUD et al.
All the products 4a-4x were characterized by IR, 1H- 13C NMR, and also by comparing
their physical characteristics with those in the literature.
Physical and spectral data of unknown products
4-(3,5-Dimethoxyphenyl)-5-ethoxycarbonyl-6-methyl-3,4-dihydropyrimidin-2(1H)-
one(4e)
M.p. 205-208 °C, 1H NMR (DMSO-d6): δ (ppm) = 9.26 (s, 1H, N1-H), 7.78 (d, J = 1.87, 1H,
N3-H), 6.37-6.42 (m, 3H, CHarom), 5.10 (d, J = 3.38 , 1H, CH), 3.71(s, 6H, Ar-OCH3)2), 3.6
(s, 3H, COOCH3), 2.25 (s, 3H, CH3); 13C N MR (DMSO-d6): δ (ppm) = 166.3, 160.9,
152.7, 149.3, 147.2, 104.8, 99.0, 98.7, 55.5, 53.9, 51.3, 18.2.
5-Ethoxycarbonyl-4-(3-fluorophenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one(4k)
1
M.p. 209-211 °C, H NMR (DMSO-d6): δ (ppm) = 9.28 (s, 1H, N1-H), 7.88 (s, 1H, N3-H),
7.35-7.44 (m, 1H, CHarom), 6.98-7.13 (m, 3H, CHarom), 5.19 (d, J = 3.42 Hz, 1H, CH), 3.48
(s, 3H, OCH3), 2.27 (s, 3H, CH3); 13C NMR (DMSO-d6): δ (ppm) = 164.5, 166.2, 152.5,
149.6, 147.8, 131.0, 122.6, 114.4, 113.5, 98.9, 53.7, 51.3.
4-(3,5-Dimethoxyphenyl)-5-methoxycarbonyl-6-methyl-3,4-dihydropyrimidin-
2(1H)-one(4n)
M.p. 191-193 °C, 1H NMR (DMSO-d6): δ (ppm)= 9.26 (s, 1H, N1-H), 7.78 (d, J = 1.87, 1H,
N3-H), 6.37-6.42 (m, 3H, CHarom), 5.10 (d, J = 3.38 , 1H, CH), 3.71(s, 6H, Ar-OCH3)2), 3.6
(s, 3H, COOCH3), 2.25 (s, 3H, CH3); 13C NMR (DMSO-d6): δ (ppm) = 166.3, 160.9, 152.7,
149.3, 147.2, 104.8, 99.0, 98.7, 55.5, 53.9, 51.3, 18.2.
4-(3-Fluorophenyl)-5-methoxycarbonyl-6-methyl-3,4-dihydropyrimidin-2(1H)-
one (4q)
M.p. 226-229 °C, 1H NMR (DMSO-d6): δ (ppm)= 9.28 (s, 1H, N1-H), 7.88 (s, 1H, N3-H),
7.35-7.44 (m, 1H, CHarom), 6.98-7.13 (m, 3H, CHarom), 5.19 (d, J = 3.42 Hz, 1H, CH), 3.48
(s, 3H, OCH3), 2.27 (s, 3H, CH3) ; 13C NMR (DMSO-d6): δ (ppm) = 164.5, 166.2, 152.5,
149.6, 147.8, 131.0, 122.6, 114.4, 113.5, 98.9, 53.7, 51.3.
5-Acetyl-4-(3,5-dimethoyphenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one (4t)
1
M.p. 196-198 °C, H NMR (DMSO-d6): δ (ppm)= 9.22 (s, 1H, N1-H), 7.76 (s, 1H, N3-H),
6.49 (s, 3H, CHarom H), 5.22 (d, 3J=3.22Hz, 1H, CH), 3.71 (s, 6H, Ph-(OCH3)2), 2.24 (s, 3H,
COCH3), 2.12 (s, 3H, CH3); 13C NMR (DMSO-d6): δ (ppm)= 194.8, 161.0, 152.6, 148.7,
146.7, 109.5, 105.1, 98.7, 55.5, 54.1, 30.7, 19.3.
5-Acetyl-4-(2,4-dichlorophenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one (4u)
1
M.p. 225-227 °C, H NMR (DMSO-d6): δ (ppm) = 9.35 (s, 1H, N1-H), 7.84 (s, 1H, N3-H),
7.61 (s, 1H, CHarom9), 7.28 (d, J = 8.4 Hz, 1H, CHarom11), 7.42 (d, J = 8.4 Hz, 1H, CHarom12),
5.63 (d, J = 3.27 Hz, 1H, CH), 2.34 (s, 3H, COCH3), 2.09 (s, 3H, CH3); 13C NMR (DMSO-d6):
δ (ppm)= 194.3, 176.3, 149.5, 140.5, 133.3, 133.2, 130.3, 129.4, 128.4, 108.8, 51.6, 30.7, 19.4.
5-Acetyl-4-(3-fluorophenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one(4w)
1
M.p. 254-256 °C, H NMR (DMSO-d6): δ (ppm)= 9.27 (s, 1H, N1-H), 7.91 (s, 1H, N3-H),
7.35-7.44 (m, 3H, CHarom), 7.35-7.44 (m, 1H, CHarom), 5.28 (d, J = 3.50 Hz, 1H, CH), 2.30
(s, 3H, COCH3), 2.15 (s, 3H, CH3); 13C NMR (DMSO-d6): δ (ppm) = 194.6, 164.5, 152.5,
149.1, 147.6, 147.5, 131.0, 130.9, 122.8, 109.8, 53.6, 30.9, 19.4.

Gypsum-catalyzed One-Pot Synthesis
315
5-Acetyl-4-(2-methylphenyl)-6-methyl-3,4-dihydropyrimidin-2(1H)-one (4x)
1
M.p. 208-210 °C, H NMR (DMSO-d6): δ (ppm) = 9.19 (s, 1H, N1-H), 7.72 (s, 1H, N3-H),
7.39-6.87 (m, 4H, CHarom), 5.48 (s, 1H, CH), 3.82 (s, 3H, COCH3), 2.11 (s, 3H, CH3);
13C NMR (DMSO-d6): δ (ppm) = 195.0, 156.7, 152.6, 148.6, 131.5, 129.4, 127.2, 120.8,
111.7, 108.1, 55.8, 49.1, 30.1, 19.1.
Results and Discussion
To evaluate the effect of the catalyst under different reaction conditions, the reaction of
benzaldehyde, ethyl acetoacetate and urea was selected as a model reaction and the results
are presented in Table 1. The best result was achieved by carrying out the reaction with
(1:1:1) mole ratio of benzaldehyde, ethyl acetoacetate and urea at 100 oC.
Although ethanol and acetonitrile (Table 1, entries 4 and 5) were found to be effective,
considering stringent environmental regulations, solvent free reactions are desired.
Therefore, we intended the Biginelli reaction under solvent free conditions to determine the
optimum amount of catalyst (Table 1, entries 6-10). The activity of the recycled catalyst was
also examined under the optimized conditions and the desired product were obtained in 85,
84, 85% yields after 1-3 runs, respectively (Table 1, entry 11).
Table 1. Effect of catalysts under different reaction conditions for condensation of
benzaldehyde, ethyl acetoacetate and ureaa.
Amounts of CaSO4.2 H2O, Refluxing
mol %
20
Entry
Solvent
Yield , %b
time, min
180
1
2
THF
55
70
Toluene
20
20
20
20
20
05
10
15
25
15
180
180
180
180
120
120
120
120
120
120
3
Diethyl ether
Acetonitrile
Ethanol
65
4
88
5
75
6
Free solvent
Free solvent
Free solvent
Free solvent
Free solvent
Solvent-free
85
7
45
8
70
9
85
10
11c
85
85,84, 85
aReaction condition: benzaldehyde (5 mmol), ethylacetoacetate (5 mmol), urea (5 mmol) and catalyst
in solvent, (5 mL, entries 1–5) at reflux. bIsolated yield. cCatalyst was recycled for three times.
Promoted by this success, we extended this reaction of urea with a range of other
1,3-dicarbonyl compounds and aldehydes, under similar conditions, furnishing the
corresponding 3,4-dihydropyimidin-2(1H)-ones (4a-x) in good yields. The generality and
scope of the reaction are summarized in Table 2.
For comparison purposes, yields obtained for 4a, 4c and 4f using Hekmatshoar37
conditions (NiSO4.7H2O in CH3CN, reflux 1.5 h, method B), Shaabani38 conditions
(LiHSO4, solvent free, 4 h, method C) and Reddy39 conditions (Montmonillonite KSF, 48 h,
method D) are given in Table 2. It is remarkable to note that the present method
(CaSO4.2H2O, solvent free at 100 °C, method A) gave good yields in shorter reaction times.

316
TAOUES BOUMOUD et al.
Table 2. CaSO4·2H2O-catalyzed synthesis of dihydropyrimidinones under solvent free
conditions
Yield, %
Melting point, °C
Founde
Reported
Time,
min
R
R1
Ab Bc Cd De
1
2
3
4
5
6
7
8
9
C6H5- OC2H5 90
4-(CH3O)-C6H4- OC2H5 95
85 80 57 82 204-206 206-20730,31
4a
4b
4c
4d
4e
4f
4g
4h
4i
80
85 80 66
204-205 203-20430
218-220 215-21630
204-205 207-20815
4-(CH3)-C6H4-
2-(CH3)-C6H4-
OC2H5 80
OC2H5 120
80
80
3,5-(CH3O)2C6H3- OC2H5 90
4-Cl-C6H4- OC2H5 105
4-N-(CH3)2C6H4- OC2H5 120
205-208
-
82 80
75
85
211-213 212-21415
257-259 256-25832
230-233 230-23233
194-196 193-19532
247-248 248-25034
4-(HO)-C6H4-
3-(Cl)-C6H4-
OC2H5 90
OC2H5 60
OC2H5 90
OC2H5 60
OCH3 65
OCH3 120
80
85
10 2,4-(Cl)2-C6H3-
11 3-F-C6H4-
12 C6H5-
4j
85
80
209-211
-
4k
4l
211-214 211-21335
194-196 193-19615
13 4-(CH3O)-C6H4-
85
82
4m
4n
4o
4p
4q
4r
4s
14 3,5(CH3O)2C6H3- OCH3 55
191-193
-
15 2-(CH3)-C6H4-
16 2,4-(Cl)2-C6H3-
17 3-F-C6H4-
18 4-(Cl)-C6H4-
19 C6H5-
OCH3 60
OCH3 120
OCH3 90
OCH3 75
85
80
239-241 240-24230,31
257-259 255-25735
80
88
226-229
-
203-206 204-20535
233-235 232-23518
CH3
CH3
CH3
CH3
CH3
CH3
65
60
85
70
20 3,5-(CH3O)2-
21 2,4-(Cl)2-C6H3-
22 4-(Cl)-C6H4-
23 3-F-C6H4-
196-198
225-227
227-229 230-23236
-
-
4t
120
75
85
85
4u
4v
4w
4x
70
55
80
85
254-256
208-210
-
-
24 2-(CH3)-C6H4-
1
aAll products were characterized by H, 13C NMR and IR spectroscopy.b Method A: using our new
c
conditions (cat. CaSO4.2H2O, solvent free at 100 °C). Method B : using R. Hekmatshoar conditions
d
(Cat. NiSO4.7H2O in CH3CN, reflux 1.5 h)37. Method C: using A. Shaabani conditions (cat. LiHSO4,
solvent free, 4 h)38. eMethod D: using K. R. Reddy conditions (Montmonillonite KSF, 48 h)39. fMelting
points are uncorrected.
Moreover, the condensation protocol is fairly general and several functionalities
including chloro, hydroxyl, methoxy, fluoro and amino do survive during the course of the
reaction to give the corresponding DHPMs in moderate to good yields with high purity.
Conclusion
We have developed a potential catalyst for the synthesis of an important class of products
known under the acronym of DHPMs. The easy handling and workup combined with the
easy available, non expensive, non toxic and recycled catalyst; good yields, short reaction
periods and the needless reaction solvents are salient features of the catalyst that render the
presented procedure relatively environmentally acceptable. Moreover, the compatibility with
various functional groups should make the present method useful and important in addition
to the known methodologies for the Biginelli reaction.

Gypsum-catalyzed One-Pot Synthesis
317
Acknowledgment
We gratefully acknowledge the MESRES (Ministère de l’Enseignement Supérieur et de la
Recherche Scientifique) for financial support.
References
1.
(a) Zhu J and Bienayme H, Eds.; Multicomponent Reactions, Wiley-VCH Weinheim,
2005; (b) Beck B, Hess S and Dömling A, Bioorg Med Chem Lett., 2000, 10(15),
1701-1705.
2.
3.
(a). Hulme C and Gore V, Curr Med Chem., 2003, 10, 51-80; (b) Grimmett M R,
Imidazole and Benzimidazole Synthesis , Academic Press, London, 1997.
(a) Ugi I, Dömling A and Werner B, J Heterocycycl Chem., 2000, 37, 647; (b) Bienayme
H, Hulme C, Oddon G and Schmitt P, Chem Eur J., 2000, 6, 3221-3227; (c) Danks T N,
Tetrahedron Lett., 1999, 40, 3957-3960; (d) Bougrin K and Soufiaoui M, Tetrahedron
Lett., 1995, 36, 3683-3686; (e) Ohberg L and Westman J, Synlett, 2001, 1296-1298;
(f) Ranu B C, Hajra A and Jana U, Tetrahedron Lett., 2000, 41, 531-533.
Biginelli P, Gazz, Chim Ital., 1893, 23, 360.
4.
5.
6.
Kappe C O, Tetrahedron, 1993, 49, 6937.
(a) Atwal K S, Swanson B N, Unger S E, Floyd D M, Moreland S, Hedberg A and
O’Reilly B C, J Med Chem., 1991, 34, 806-811; (b) Rovnyak G C, Kimball S D,
Beyer B, Cucinotta G, DiMarco J D, Gougoutas J Z, Hedberg A, Malley M F,
McCarthy, J P, Zhang R and Moreland S, J Med Chem., 1995, 38, 119.
(a) Kumar K A, Kasthuraiah M, Reddy C S and Reddy C D, Tetrahedron Lett., 2001,
42, 7873-7875; (b) Chitra S and Pandiarajan K, Tetrahedron Lett., 2009, 50, 2222-2224.
Ranu B C, Hajra A and Jana U, J Org Chem., 2000, 65, 6270.
7.
8.
9.
Reddy Ch V, Mahesh M, Raju P V K, Babu T R and Reddy V V N, Tetrahedron
Lett., 2002, 43, 2657.
10. Yadav J S, Reddy B V S, Srinivas R, Venugopal C and Ramalingam T, Synthesis,
2001,1341.
11. Paraskar A S, Dewkar G K and Sudalai A, Tetrahedron Lett., 2003, 44, 3305-3308.
12. Fu N Y, Yuan Y F, Cao Z and Wang S W, Wang J T and Peppe C, Tetrahedron,
2002, 58, 4801.
13. Tu S, Fang F, Zhu S, Li T, Zhang X and Zhuang Q, Synlett., 2004, 537.
14. Xia M and Wang Y G, Tetrahedron Lett., 2002, 43, 7703.
15. Bose D S, Fatima L and Mereyala H B, J Org Chem., 2003, 68, 587.
16. Dondoni A and Massi A, Tetrahedron Lett., 2001, 42, 7975.
17. Ma Y, Qian C, Wang L and Yang M, J Org Chem., 2000, 65, 3864-3868.
18. Shaabani A, Bazgir A and Teimouri F, Tetrahedron Lett., 2003, 44, 857.
19. Peng J and Deng Y, Tetrahedron Lett., 2001, 42, 5917-5919.
20. (a) Bigi F, Carloni S, Frullanti B, Maggi R and Sartori G, Tetrahedron Lett., 1999,
40, 3465-3468; (b) Zhang H, Zhou Z, Yao Z, Xu F and Shen Q, Tetrahedron Lett.,
2009, 50, 1622-1624.
21. Yadav J S, Reddy B V S, Reddy E J and Ramalingam T, J Chem Research(S), 2000, 354.
22. Kappe C O, Kumar D and Varma R S, Synthesis, 1999, 1799.
23. Stadler A and Kappe C O, J Chem Soc Perkin Trans., 2000, 2, 1363-1368.
24. Stefani H A and Gatti P M, Synth Commun., 2000, 30, 2165-2173.
25. (a)Yadav J S, Reddy B V S, Reddy K B, Raj K S and Prasad A R, J Chem Soc Perkin
Trans., 2001, 1, 1939-1941.

318
TAOUES BOUMOUD et al.
26. Toda F and Tanaka K, Chem Rev., 2000, 100, 1025-1074.
27. Boumoud T, Boumoud B, Rhouati S, Belfaitah A, Debache A and Mosset P, Acta
Chim Slov., 2008, 55, 617-622.
28. Boumoud T, Boumoud B, Rhouati S, Belfaitah A, Debache A and Mosset P, E-J Chem.,
2008, 5, 688.
29. Debache A, Boumoud B, Amimour M, Belfaitah A, Rhouati S and Carboni B,
Tetrahedron Lett., 2006, 47, 5697.
30. Zumpe F L, Flüß M, Schmitz K and Lender A, Tetrahedron Lett., 2007, 48, 1421.
31. Kappe C O, Kumar D and Varma R S, Synthesis, 1999, 1799-1803.
32. Lu J and Bai Y, Synthesis, 2002, 466-470.
33. Fu N-Y, Yuan Y-F, Cao Z, Wang S W, Wang J T and Peppe C, Tetrahedron, 2002,
58, 4801.
34. (a) Tu S, Fang F, Miao C, Jiang H, Feng Y, Shi D and Wang X, Tetrahedron Lett.,
2003, 44, 6153; (b) Lu J, Bai Y, Wang Z, Yang B and Ma H, Tetrahedron Lett.,
2000, 41, 9075.
35. Li J T, Han J F, Yang J H and Li T S, Ultrason Sonochem., 2003, 10, 119-122.
36. Yarim M, Sarac S, Ertan M, Batu O and Erol K, Il Farmaco, 1999, 54, 359.
37. Hekmatshoar R, Heidari M, Heravi M M and Baghernejad B, J Korean Chem Soc.,
2009, 53( 1), 90.
38. Shaabani A, Bazgir A, Arab-Ameri S, Kiasaraie M S and Samadi S, Iran J Chem
Chem Eng., 2005, 24, 67.
39. Reddy K R, Reddy Ch V, Mahesh M, Raju P V K and Reddy V V N, Tetrahedron
Lett., 2003, 44, 8173-8175.

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