Abstract
Despite prior reports of several really effective catalytic and non-catalytic approaches towards Biginelli’s 3,4-dihydropyrimidin-2(1H)-ones, an overwhelming number of new catalysts for the Biginelli reaction have been recently published. Most of the catalysts are somewhat exotic, expensive, harmful and even uneffective in the absence of acidic additives. Herein we reduce the “yet-another-one-catalyst” idea to absurdity by proposing NaCl promotes the reaction that actually requires no catalyst, neither rare nor expensive.
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References
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NH2SO3H/grinding/sf/rt: Jin T, Zhao Y, Liu L, Li T (2006) Synthesis of 1,2,3,6-tetrahydropyrimidin-2-one derivatives by grinding method. Chin J Org Chem 26:975–978
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Silica sulfuric acid/sf: Salehi P, Dabiri M, Zolfigol MA, Bodaghi Fard MA (2003) Efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones over silica sulfuric acid as a reusable catalyst under solvent-free conditions. Heterocycles 60:2435–2440
Silica sulfuric acid/sf: Chen WY, Qin SD, Jin JR (2007) Efficient Biginelli reaction catalyzed by sulfamic acid or silica sulfuric acid under solvent-free conditions. Synth Commun 37:47–52
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Montmorillonite KSF clay/MWI/sf: Mitra AK, Banerjee K (2003) Clay catalysed synthesis of dihydropyrimidinones under solvent-free conditions. Synlett 2003:1509–1511
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TMSCl: Zhu Y, Huang S, Pan Y (2005) Highly chemoselective multicomponent Biginelli-type condensations of cycloalkanones, urea or thiourea and aldehydes. Eur J Org Chem 2005: 2354–2367
TMSCl/rt: Zhu Y, Pan Y, Huang S (2004) Trimethylsilyl chloride: a facile and efficient reagent for one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Synth Commun 34:3167–3174
Ag3PW12O40: Yadav JS, Subba Reddy BV, Sridhar P, Reddy JSS, Nagaiah K, Lingaiah N, Saiprasad PS (2004) Green protocol for the Biginelli three-component reaction: Ag3PW12O40 as a novel, water-tolerant heteropolyacid for the synthesis of 3,4-dihydropyrimidinones. Eur J Org Chem 2004:552–557
SmI2/sf: Han X, Xu F, Luo Y, Shen Q (2005) An efficient one-pot synthesis of dihydropyrimidinones by a Samarium diiodide catalyzed Biginelli reaction under solvent-free conditions. Eur J Org Chem 2005:1500–1503
ZnCl2/sf: Sun Q, Wang Y, Ge Z, Cheng T, Li R (2004) A highly efficient solvent-free synthesis of dihydropyrimidinones catalyzed by zinc chloride. Synthesis 2004:1047–1051
PPA/PEG400 support/MWI/sf: Xia M, Wang Y (2003) An efficient protocol for the liquid-phase synthesis of methyl 3,4-dihydropyrimidin-2(1H)-one-5-carboxylate derivatives. Synthesis 2003:262–266
FeCl36H2O or NiCl26H2O/EtOH: Lu J, Bai Y (2002) Catalysis of the Biginelli reaction by ferric and nickel chloride hexahydrates. One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Synthesis 2002:466–470
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[BMim][BF4]: Putilova ES, Troitskii NA, Zlotin SG, Khudina OG, Burgart YaV, Saloutin VI, Chupakhin ON (2006) One-step solvent-free synthesis of fluoroalkyl-sbstituted 4-hydroxy-2-oxo(thioxo)hexahydropyrimidines in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate. Russ J Org Chem 42: 1392–1395
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Polymer-supported IL: Wang ZT, Wang SC, Xu LW (2005) Polymer-supported ionic-liquid-catalyzed synthesis of 1,2,3,4-tetrahydro-2-oxopyrimidine-5-carboxylates via Biginelli reaction. Helv Chim Acta 88:986–989
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[Bmim][FeCl4]: Chen X, Peng Y (2008) Chloroferrate (III) ionic liquid: efficient and recyclable catalyst for solvent-free synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Catal Lett 122:310–313
1-n-Butyl-3-methylimidazolium saccharinate ([BMIm]Sac): Li M, Guo W-S, Wen L-R, Li Y-F, Yang H-Z (2006) One-pot synthesis of Biginelli and Hantzsch products catalyzed by non-toxic ionic liquid (BMImSac) and structural determination of two products. J Mol Catal A Chem 258:133–138
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DSA/H2O/rt: Sharma SD, Gogoi P, Konwar B (2007) A highly efficient and green method for the synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by dodecyl sulfonic acid in water. Green Chem 9:153–157
PEG 400/sf/100◦C: Jain SL, Singhal S, Sain B (2007) PEG-assisted solvent and catalyst free synthesis of 3,4-dihydropyrimidinones under mild reaction conditions. Green Chem 9: 740–741
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Me3SiI/MeCN/rt: Sabitha G, Reddy KB, Srinivas R, Yadav JS (2005) Iodotrimethylsilane-accelerated one-pot synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones: a novel procedure for the Biginelli-like cyclocondensation reaction at room temperature. Helv Chim Acta 88:2996–2999
FeCl36H2O/Me3SiCl: Xu LW, Wang ZT, Xia CG, Li L, Zhao PQ (2004) Improved protocol for the three-component Biginelli reactions and Biginelli-like Mannich reactions of carbamates, aldehydes, and ketones. Helv Chim Acta 87: 2608–2612
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Dowex50W/H2O/70◦C: Mukhopadhyay C, Datta A, Banik BK (2006) Dowex 50W in aqueous medium: highly efficient Biginelli condensation procedure for the synthesis of 4-aryl-3,4-dihydropyrimidones. Heterocycles 71:181–188
K5CoW12O403H2O/sf: Subhas Bose D, Venu Chary M, Mereyala HB (2006) Water-tolerant and reusable catalyst for the one-pot synthesis of dihydropyrimidin-2(1H)-ones under solvent-free conditions. Heterocycles 68:1217–1224
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SnCl22H2O: Kumar S, Saini A, Sandhu JS (2004) Tin (II) chloride catalyzed one pot efficient and novel preparation of dihydropyrimidin-2(1H)-ones. Indian J Chem 43B:1485–1486
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BiOClO4nH2O/MeCN: Thirupathi Reddy Y, Narsimha Reddy P, Sunil Kumar B, Rao GVP, Rajitha B (2005) Bismuth oxide perchlorate catalysed efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones: an improved high yielding protocol for the Biginelli reaction. Indian J Chem 44B:1304–1306
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CaCl2/MWI/sf: Misra AK, Agnihotri G, Madhusudan SK (2004) Microwave induced eco-friendly solvent-free Biginelli reaction catalyzed by calcium chloride. Indian J Chem 43B:2018–2020
CoCl26H2O/MWI/sf, MnCl24H2O/MWI/sf, SnCl22H2O/MWI/sf: Kumar S, Saini A, Sandhu JS (2005) Cobalt(II) chloride or manganese (II) chloride or tin (II) chloride promoted one pot synthesis of dihydropyrimidin-2(1H)-ones using microwave irradiation. Indian J Chem 44B:762–767
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Binol- and H8-binol-based phosphoric acids/CH2Cl2/rt: Chen XH, Xu XY, Liu H, Cun LF, Gong LZ (2006) Highly enantioselective organocatalytic Biginelli reaction. J Am Chem Soc 128:14802–14803
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Propane phosphonic acid anhydride (n-C3H7PO2)3/AcOEt: Zumpe FL, Flüß M, Schmitz K, Lender A (2007) Propane phosphonic acid anhydride: a new promoter for the one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Tetrahedron Lett 48:1421–1423
(L)-Pro-OMe × HCl: Mabry J, Ganem B (2006) Studies on the Biginelli reaction: a mild and selective route to 3,4-dihydropyrimidin-2(1H)-ones via enamine intermediates. Tetrahedron Lett 47:55–56
Cu(NTf2)2, or Ni(NTf2)2, or Yb(NTf2)3/H2O/rt: Suzuki I, Suzumura Y, Takeda K (2006) Metal triflimide as a Lewis acid catalyst for Biginelli reactions in water. Tetrahedron Lett 47:7861–7864
PhB(OH)2/MeCN: Debache A, Boumoud B, Amimour M, Belfaitah A, Rhouati S, Carboni B (2006) Phenylboronic acid as a mild and efficient catalyst for Biginelli reaction. Tetrahedron Lett 47:5697–5699
Zn(NH2SO3)2: Zhang M, Li YQ, Zhou MY (2006) Rapid synthesis of 1,2,3,4-tetrahydropyrimidin-2-ones using Zn(NH2SO3)2 as a catalyst under microwave irradiation. Chin J Chem 24:282–284
Zn(NH2SO3)2: Zhang M, Li YQ (2006) Facile one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-one catalyzed by Zn(NH2SO3)2. Synth Commun 36:835–841
Dowex-50W/130◦C/sf: Singh K, Arora D, Singh S (2006) Dowex-promoted general synthesis of N,N′-disubstituted-4-aryl-3,4-dihydropyrimidinones using a solvent-free Biginelli condensation protocol. Tetrahedron Lett 47:4205–4207
ZnI2/MWI/sf: Liang B, Wang X, Wang JX, Du Z (2007) New three-component cyclocondensation reaction: microwave-assisted one-pot synthesis of 5-unsubstituted-3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. Tetrahedron 63:1981–1986
KHSO4/glycol/100◦C: Tu S, Fang F, Zhu S, Li T, Zhang X, Zhuang Q (2004) A new Biginelli reaction procedure using potassium hydrogen sulfate as the promoter for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one. Synlett 2004:537–539
KHSO4/glycol: Tu S, Fang F, Zhu S, Li T, Zhang X, Zhuang Q (2004) A new Biginelli reaction procedure using potassium hydrogen sulfate as the promoter for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one. J Heterocycl Chem 41:253–257
KHSO4/AcOH/80◦C: Shi F, Jia R, Zhang X, Tu S, Yan S, Zhang Y, Jiang B, Zhang J, Yao C (2007) Extension of the Biginelli-type reaction: one-pot synthesis of Pyrimido-pyrimidines and Spirobi[pyrimidine]s using potassium hydrogen sulfate as a catalyst. Synthesis 2007:2782–2790
Shaabani A, Bazgir A, Arab-Ameri S, Sharifi Kiasaraie M, Samadi S (2005) Comparison of catalytic effect of alkali and alkaline earth metals hydrogen sulfate: as the promoter for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. Iran J Chem & Chem Eng 24(3): 67
LiClO4 or LiOTf/MeCN: Yadav JS, Subba Reddy BV, Srinivas R, Venugopal C, Ramalingam T (2001) LiClO-Catalyzed one-pot synthesis of dihydropyrimidinones: an improved protocol for Biginelli reaction. Synthesis 2001:1341–1345
In(OTf)3/MWI/Na2SO4 solid support: Shanmugam P, Annie G, Perumal PT (2003) Synthesis of novel 3,4-dihydropyrimidinones on water soluble solid support catalyzed by indium triflate. J Heterocycl Chem 40:879–883
Al2O3(acidic)/MWI/sf: Kidwai M, Mohan R, Saxena S (2003) Solid-supported Hantzsch-Biginelli reaction for syntheses of pyrimidine derivatives. Russ Chem Bull Int Ed 52: 2457–2460
Al2O3(acidic) or montmorillonite K10 clay/MWI/sf: Kidwai M, Bala S, Mishra AD (2004) Microwave assisted synthesis of thiadiazolopyrimidin-2-thiones. Indian J Chem 43B: 2485–2487
P2O5/EtOH: Deshmukh MB, Anbhule PV, Jadhav SD, Mali AR, Jagtap SS, Deshmukh SA (2007) An efficient, simple, one-pot synthesis of dihydropyrimidine-2(1H)-ones using phosphorus pentoxide. Indian J Chem 46B:1545–1548
LaCl3 × 7H2O/HCl/EtOH: Lu J, Bai YJ, Wang ZJ, Yang B, Ma HR (2000) One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using lanthanum chloride as a catalyst. Tetrahedron Lett 41:9075–9078
CoCl2 × 6H2O or LaCl3 × 7H2O/HCl/EtOH: Lu J, Bai YJ, Guo YH, Wang ZJ, Ma HR (2002) CoCl2 × 6H2O or LaCl3 × 7H2O Catalyzed Biginelli reaction. One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Chinese J Chem 20:681–687
TsOH/AcOH/MWI: Tu SJ, Fang F, Miao CB, Jiang H, Shi DQ (2003) One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using TsOH as a catalyst under microwave irradiation. Chin J Chem 21:706–709
SnCl2 or CuCl2 × 2H2O or FeCl3 × 6H2O or ZnCl2/HCl/MWI/sf: Xue S, Shen YC, Li YL, Shen XM, Guo QX (2002) Synthesis of 4-Aryl-3,4-dihydropyrimidinones using Microwave-assisted solventless Biginelli reaction. Chin J Chem 20:385–389
La(OTf)3/100◦C/sf: Chen RF, Qian CT (2002) One-pot syntheses of 3,4-dihydropyrimidine-2(1H)-thiones catalyzed by La(OTf)3. Chin J Chem 20:427–430
Zn(OTf)2/100◦C/sf: Xu H, Wang YG (2003) A rapid and efficient Biginelli reaction catalyzed by zinc triflate. Chin J Chem 21:327–331
SmCl3 × 6H2O/Montmorillonite clay/sf/MWI: Li YX, Bao WL (2003) Microwave-assisted solventless Biginelli reaction catalyzed by montmorillonite clay-SmCl3 × 6H2O system. Chin Chem Lett 14:993–995
FeCl3 × 6H2O/HCl/EtOH: Lu J, Ma H (2000) Iron(III)-catalyzed synthesis of dihydropyrimidinones. Improved conditions for the Biginelli reaction. Synlett 2000:63–64
Zorkun IS, Sarac S, Celebib S, Erol K (2006) Synthesis of 4-aryl-3,4-dihydropyrimidin-2(1H)-thione derivatives as potential calcium channel blockers. Bioorg Med Chem 14: 8582–8589
Polyaniline-Bismoclite complex/EtOH: Gangadasu B, Palaniappan S, Rao VJ (2004) One-pot synthesis of dihydropyrimidinones using polyaniline-bismoclite complex. A facile and reusable catalyst for the Biginelli reaction. Synlett 2004:1285–1287
HCl/AcOH: Folkers K, Harwood HJ, Johnson TB (1932) Researches on pyrimidines. CXXX. Synthesis of 2-keto-1,2,3,4-tetrahydropyrimidines. J Am Chem Soc 54:3751–3758
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HCl/AcOH: Aslanoglu F, Akbas E, Sönmez M, Anil B (2007) 5-Benzoyl-4,6-diphenyl-1,2,3,4-tetrahydro-2 thioxopyrimidine. Phosphorus Sulfur Silicon Relat Elem 182: 1589–1597
NBS/EtOH/MWI: Hazarkhani H, Karimi B (2004) N-Bromosuccinimide as an almost neutral catalyst for efficient synthesis of dihydropyrimidinones under microwave irradiation. Synthesis 2004:1239–1242
CdCl2/MeCN: Venkat Narsaiah A, Basak AK, Nagaiah K (2004) Cadmium chloride: an efficient catalyst for one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Synthesis 2004: 1253–1256
I2/EtOH vs HCl/EtOH: Folkers K, Johnson TB (1933) Researches on pyrimidines. CXXXVI. The mechanism of formation of tetrahydropyrimidines by the Biginelli reaction. J Am Chem Soc 55:3784–3791
I2/MeCN: Srinivas KVNS, Das B (2004) Iodine catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones and thiones: a simple and efficient procedure for the Biginelli reaction. Synthesis 2004:2091–2093
I2/PhMe: Bhosale RS, Bhosale SV, Bhosale SV, Wang T, Zubaidha PK (2004) An efficient, high yield protocol for the one-pot synthesis of dihydropyrimidin-2(1H)-ones catalyzed by iodine. Tetrahedron Lett 45:9111–9113
RuCl3/100◦C/sf: De SK, Gibbs RA (2005) Ruthenium(III) chloride-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions. Synthesis 2005:1748–1750
RuCl3 × nH2O/rt/EtOH: Jain SL, Sharma VB, Sain B (2006) Ruthenium-catalyzed Biginelli condensation: a simple and efficient one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones under mild reaction conditions. J Heterocyclic Chem 43: 777–779
Polystyrenesulfonic acid (PSSA)/H2O/MWI: Polshettiwara V, Varma RS (2007) Biginelli reaction in aqueous medium: a greener and sustainable approach to substituted 3,4-dihydropyrimidin-2(1H)-ones. Tetrahedron Lett 48:7343–7346
Bi(NO3)3/sf: Banik BK, Reddy AT, Datta A, Mukhopadhyay C (2007) Microwave-induced bismuth nitrate catalyzed synthesis of dihydropyrimidones via Biginelli condensation under solventless conditions. Tetrahedron Lett 48:7392–7394
Bi(NO3)3 × 5H2O: Khodaei MM, Khosropour AR, Bigzadeh M (2004) An efficient and environmentally friendly method for synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by Bi(NO3)3 × 5H2O. Synth Commun 34:1551–1557
Bakers’ yeast/D-glucose/phosphate buffer pH 7/rt: Kumar A, Maurya RA (2007) An efficient bakers’ yeast catalyzed synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Tetrahedron Lett 48:4569–4571
4-MeC6H4S(O)OH: Shutalev AD, Sivova NV (1998) Synthesis of 4-Alkyl-substituted 1,2,3,4-tetrahydropyrimidin-2-ones by the Biginelli reaction. Chem Heterocycl Comp 34:848–851
H2SO4/H2O: Hassani Z, Islami MR, Kalantari M (2006) An efficient one-pot synthesis of octahydroquinazolinone derivatives using catalytic amount of H2SO4 in water. Bioorg Med Chem Lett 16:4479–4482
H2SO4/EtOH: Bussolari JC, McDonnell PA (2000) A new substrate for the Biginelli cyclocondensation: direct preparation of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones from a β-keto carboxylic acid. J Org Chem 65:6777–6779
H2SO4/AcOH: Folkers K, Johnson TB (1933) Researches on pyrimidines. CXXXIV. The reaction of phenylacetaldehyde and acetophenone with urea. J Am Chem Soc 55:3361–3368
SnCl2 × 2H2O/LiCl: Shailaja M, Manjula A, Vittal Rao B, Parvathi N (2004) Simple protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using SnCl2 × 2H2O-LiCl as an inexpensive catalyst system. Synth Commun 34:1559–1564
Al(HSO4)3/MeOH or sf: Khodaei MM, Salehi P, Zolfigol MA, Sirouszadeh S (2004) Efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones by aluminum hydrogensulfate. Polish J Chem 78:385–388
MeSO3H/EtOH: Jin TS, Wang HX, Xing CY, Li XL, Li TS (2005) An efficient one-pot synthesis of 3,4-dihydropyrimidin-2-ones catalyzed by methanesulfonic acid. Synth Commun 34:3009–3016
Sc(OTf)3/MeCN: De SK, Gibbs RA (2005) Scandium(III) triflate as an efficient and reusable catalyst for synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Synth Commun 35:2645–2651
MgCl2 × 6H2O/80◦C/sf: Zhang GL, Cai XH (2005) Magnesium chloride hexahydrate catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. Synth Commun 35:829–833
H6P2W18O62 × 24H2O/MeCN or sf: Romanelli GP, Sathicq AG, Autino JC, Baronetti G, Thomas HJ (2007) Solvent-free approach to 3,4-dihydropyrimidin-2(1H)-(thio)ones: Biginelli reaction catalyzed by a Wells-Dawson reusable heteropolyacid. Synth Commun 37:3907–3916
BiONO3/MeCN: Reddy YT, Rajitha B, Reddy PN, Kumar BS, Rao VPG (2004) Bismuth subnitrate catalyzed efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones: an improved protocol for the Biginelli reaction. Synth Commun 34:3821–3825
FeCl3 × 6H2O/MWI/sf: Tu SJ, Zhou JF, Cai PJ, Wang H, Feng JC (2002) A convenient ferric chloride catalyzed synthesis of 5-alkoxycarbonyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones under microwave irradiation. Synth Commun 32:147–151
FeCl3 × 6H2O/MWI/sf or no catalyst/MWI/sf: Mirza- Aghayan M, Bolourtchian M, Hosseini M (2004) Microwave-assisted efficient synthesis of dihydropyrimidines in solvent-free condition. Synth Commun 34:3335–3341
Natural phosphate doped with metal halides MCl2 (M = Cu,Zn,Co,Ni)/PhMe: El Badaoui H, Bazi F, Tamani S, Boulaajaj S, Zahouily M, Lazrek HB, Sebti S (2005) Lewis acid-doped natural phosphate: new catalysts for the one-pot synthesis of 3,4-dihydropyrimdin-2(1H)-one. Synth Commun 35:2561–2568
CuCl2/LiCl/EtOH: Manjula A, Rao BV, Neelakantan P (2005) An inexpensive protocol for Biginelli reaction. Synth Commun 34:2665–2671
CuBr2/EtOH: Zhou H, He M, Liu C, Jiang H, Luo G (2006) One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using CuBr2 as catalyst. Prep Biochem Biotechnol 36:375–381
ZnBr2/sf: Yu Y, Liu D, Liu C, Jiang H, Luo G (2007) An efficient one-pot Biginelli condensation of aliphatic aldehydes catalyzed by zinc bromide under solvent-free conditions. Prep Biochem Biotechnol 37(4):381–387
PEG-SO3H/MWI/sf: Wang X, Quan Z, Wang F, Wang M, Zhang Z, Li Z (2006) PEG-SO3H as catalyst for 3,4-dihydropyrimidones via Biginelli reaction under microwave and solvent-free conditions. Synth Commun 36:451–456
CAN or Oxone/MeOH/sonication: Yadav JS, Reddy BVS, Reddy KB, Raj KS, Prasad AR (2001) Ultrasound-accelerated synthesis of 3,4-dihydropyrimidin-2(1H)-ones with ceric ammonium nitrate. J Chem Soc Perkin Trans 1:1939–1941
TiCl3/THF: Ramesha S, Bhojya Naik HS, Harish Kumar HN (2007) Titanium trichloride-catalysed cyclocondensation: synthesis of 2-mercaptoquinoline substituted 1,2,3,4-tetrahydropyrimidinones. J Sulfur Chem 28:573–579
PPE/MWI: Foroughifar N, Mobinikhaledi A, Fathinejad Jirandehi H (2003) Microwave assisted synthesis of some pyrimidine derivatives using polyphosphate ester (PPE) in ceramic bath. Phosphorus Sulfur Silicon Relat Elem 178:1241–1246
PPE/MWI: Foroughifar N, Mobinikhaledi A, Fathinejad Jirandehi H, Memar S (2003) Microwave-assisted synthesis of some Bi- and Tricyclic pyrimidine derivatives. Phosphorus Sulfur Silicon Relat Elem 178:1269–1276
PPE/MWI: Kappe CO, Kumar D, Varma RS (1999) Microwave-assisted high-speed parallel synthesis of 4-aryl-3,4-dihydropyrimidin-2(1H)-ones using a solventless Biginelli condensation protocol. Synthesis 1999:1799–1803
h ν/THF: Foroughifar N, Mobinikhaledi A, Fathinejad Jirandehi H (2003) Synthesis of some Biginelli compounds in solvent medium using a photochemistry method. Phosphorus Sulfur Silicon Relat Elem 178:495–500
CeCl3 × 7H2O/EtOH, H2O or sf: Bose DS, Fatima L, Mereyala HB (2003) Green chemistry approaches to the synthesis of 5-alkoxycarbonyl–4-aryl-3,4-dihydropyrimidin-2(1H)-ones by a three-component coupling of one-pot condensation reaction: comparison of ethanol, water, and solvent-free conditions. J Org Chem 68:587–590
InBr3/EtOH: Fu NY, Yuan YF, Cao Z, Wang SW, Wang JT, Peppe C (2002) Indium (III) bromide-catalyzed preparation of dihydropyrimidinones: improved protocol conditions for the Biginelli reaction. Tetrahedron 58:4801–4807
InBr3 or InCl3 × 4H2O/EtOH: Fu NY, Yuan YF, Pang ML, Wang JT, Peppe C (2003) Indium(III) halides-catalyzed preparation of ferrocenedihydropyrimidinones. J Organomet Chem 672:52–57
ZrCl4/EtOH: Venkateshwar Reddy C, Mahesh M, Raju PVK, Ramesh Babu T, Narayana Reddy VV (2002) Zirconium(IV) chloride catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Tetrahedron Lett 43:2657–2659
ZrOCl2 × 8H2O or ZrCl4/neat/100◦C: Rodriguez-Dominguez JC, Bernardi D, Kirsch G (2007) ZrCl4 or ZrOCl2 under neat conditions: optimized green alternatives for the Biginelli reaction. Tetrahedron Lett 48:5777–5780
Mn(OAc)3 × 2H2O: Kumar KA, Kasthuraiah M, Reddy CS, Reddy CD (2001) Mn(OAc)3 × 2H2O-mediated three-component, one-pot, condensation reaction: an efficient synthesis of 4-aryl-substituted 3,4-dihydropyrimidin-2-ones. Tetrahedron Lett 42:7873–7875
Ytterbium(III)-resin: Dondoni A, Massi A (2001) Parallel synthesis of dihydropyrimidinones using Yb(III)-resin and polymer-supported scavengers under solvent-free conditions. A green chemistry approach to the Biginelli reaction. Tetrahedron Lett 42:7975–7978
CuCl/BF3 × Et2O/AcOH: Hu EH, Sidler DR, Dolling UH (1998) Unprecedented catalytic three component one-pot condensation reaction: an efficient synthesis of 5-alkoxycarbonyl-4-aryl-3,4-dihydropyrimidin-2(1H)-ones. J Org Chem 63:3454–3457
CuCl/BF3 × Et2O/AcOH/mol.sieves/THF: Dondoni A, Massi A, Sabbatini S (2001) Towards the synthesis of C-glycosylated dihydropyrimidine libraries via the three-component Biginelli reaction. A novel approach to artificial nucleosides. Tetrahedron Lett 42:4495–4497
Cu(OTf)2/MeCN: Paraskar AS, Dewkar GK, Sudalai A (2003) Cu(OTf)2: a reusable catalyst for high-yield synthesis of 3,4-dihydropyrimidin-2(1H)-ones. Tetrahedron Lett 44: 3305–3308
PhCH(Me)N+Me2Bu Br−/sf/100°C: Reddy KR, Reddy CV, Mahesh M, Raju PVK, Reddy VVN (2003) New environmentally friendly solvent free synthesis of dihydropyrimidinones catalysed by N-butyl-N,N-dimethyl-α-phenylethylammonium bromide. Tetrahedron Lett 44:8173–8175
NH4Cl/sf/100◦C: Shaabani A, Bazgir A, Teimouri F (2003) Ammonium chloride-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions. Tetrahedron Lett 44:857–859
NH4Cl/ultrasound irradiation/MeOH: Stefani HA, Oliveira CB, Almeida RB, Pereira CMP, Braga RC, Cella R, Borges VC, Savegnago L, Nogueira CW (2006) Dihydropyrimidin-2(1H)-ones obtained by ultrasound irradiation: a new class of potential antioxidant agents. Eur J Med Chem 41:513–518
Phosphotungstic acid (H3PW12O40)/EtOH: Jin TS, Xiao JC, Chen YX, Li TS (2004) Phosphotungstic acid catalysed one-pot synthesis of 5-alkoxycarbonyl-4-aryl-3,4-dihydropyrimidin-2-ones. J Chem Res Synop 3:190–191
CuCl2 × 2H2O/CuSO4 × 5H2O/MWI: Gohain M, Prajapati D, Sandhu JS (2004) A novel Cu-catalysed three-component one-pot synthesis of dihydropyrimidin-2(1H)-ones using microwaves under solvent-free conditions. Synlett 2004:235–238
Ion exchange resins (Amberlyst-15, Nafion H)/AcOH/MWI: Yadav JS, Reddy BVS, Reddy EJ, Ramalingam T (2000) Microwave-assisted efficient synthesis of dihydropyrimidines: improved high yielding protocol for the Biginelli reaction. J Chem Res Synop 7:354–355
SiO2/NaHSO4/MeCN: Adharvana Chari M, Syamasundar K (2004) Silicagel supported sodium hydrogensulfate as a heterogenous catalyst for high yield synthesis of 3,4-dihydropyrimidin-2(1H)-ones. J Mol Catal A Chem 221:137–139
Silica/Fe (Ferrihydrite silica aerogels)/EtOH: Martínez S, Meseguer M, Casas L, Rodríguez E, Molins E, Moreno-Manas M, Roig A, Sabastián RM, Vallribera A (2003) Silica aerogel-iron oxide nanocomposites: recoverable catalysts in conjugate additions and in the Biginelli reaction. Tetrahedron 59:1553–1556
Lanthanide halides derived from mischmetal (LnCl3 × 7H2O)/HCl/EtOH: Lannou M-L, Hélion F, Namy J-L (2008) Applications of lanthanide trichloride hydrates, prepared from mischmetall, in the Biginelli reaction. Synlett 2008:105–107
LaCl3/graphite/HCl/MWI/sf: Khabazzadeh H, Saidi K, Sheibani H (2008) Microwave-assisted synthesis of dihydropyrimidin-2(1H)-ones using graphite supported lanthanum chloride as a mild and efficient catalyst. Bioorg Med Chem Lett 18:278–280
ClCH2CO2H/sf/90◦C: Yu Y, Liu D, Liu C, Luo G (2007) One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones using chloroacetic acid as catalyst. Bioorg Med Chem Lett 17:3508–3510
Aluminia–sulfuric acid: Besoluk S, Kucukislamoglu M, Nebioglu N, Zengin M, Arslan M (2008) Solvent-free synthesis of dihydropyrimidinones catalyzed by alumina sulfuric acid at room temperature. J Iran Chem Soc 5:62–66
Fe(HSO4)3/MeCN or sf/100◦C: Shirini F, Zolfigol MA, Abri AR (2008) Fe (HSO4)3 as an efficient catalyst for the preparation of 3,4-dihydropyrimidin-2(1H)-ones in solution and under solvent-free conditions. J Iran Chem Soc 5:96–99
CuCl2 × 2H2O/C12H25SO3Na/H2O: Xu F, Wang JJ, Tian YP (2008) New procedure for one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones by Biginelli reaction. Synth Commun 38:1299–1310
Pyrazolidine dihydrochloride: Suzuki I, Iwata Y, Takeda K (2008) Biginelli reactions catalyzed by hydrazine type organocatalyst. Tetrahedron Lett 49:3238–3241
Sr(NO3)2/AcOH: Liu CJ, Wang JD, Li YP (2006) One-pot synthesis of 3,4-dihydropyrimidin-2(1H)-(thio)ones using strontium(II) nitrate as a catalyst. J Mol Catal A Chem 258: 367–370
CuI/H2O, MeCN or sf: Kalita HR, Phukan P (2007) CuI as reusable catalyst for the Biginelli reaction. Catal Commun 8:179–182
Uronium hydrogen sulfates/sf: Salehi P, Dabiri M, Zolfigol MA, Baghbanzadeh M (2005) A green approach to the synthesis of 2,3-dihydropyrimidin-2(1H)-ones by uronium hydrogansulfate under solvent-free conditions. Heterocycles 65:1177–1181
H3PMo12O4/AcOH: Heravi MM, Bakhtiari K, Bamoharram FF (2006) 12-Molybdophosphoric acid: a recyclable catalyst for the synthesis of Biginelli-type 3,4-dihydropyrimidine-2(1H)-ones. Catal Commun 7:373–376
TiCl4/sf: Valizadeh H, Gholipur H, Zarrebin R, Amiri M, Sabzi MR (2008) Titanium(IV) Chloride catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under solvent-free conditions via three-component Biginelli reaction. Phosphorus Sulfur Silicon Relat Elem 183:1552–1555
TiCl4/EtOH/80°C: Nagawade RR, Kotharkar SA, Shinde DB (2005) Titanium(IV) chloride catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones and thiones. Mendeleev Commun 15:150–151
Supported H3PW12O40 or H3PMo12O40/MeCN: Fazaeli R, Tangestaninejad S, Aliyan H, Moghadam M (2006) One-pot synthesis of dihydropyrimidinones using facile and reusable polyoxometalate catalysts for the Biginelli reaction. Appl Catal A Gen 309:44–51
Keggin-type heteropolyacids—H3PW12O40, H3PMo12O40 or H4SiW12O40/MeCN: Rafiee E, Jafari H (2006) A practical and green approach towards synthesis of dihydropyrimidinones: using heteropoly acids as efficient catalysts. Bioorg Med Chem Lett 16:2463–2466
H3PW12O40/MWI/sf: Mishra BG, Kumar D, Rao VS (2006) H3PW12O40 catalyzed expeditious synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. Catal Commun 7:457–459
H3PW12O40 or H3PW12O40–SiO2/80°C/sf: Amini MM, Shaabani A, Bazgir A (2006) Tungstophosphoric acid (H3PW12O40): an efficient and eco-friendly catalyst for the one-pot synthesis of dihydropyrimidin-2(1H)-ones. Catal Commun 7:843–847
HBF4/sf/45°C: Chen WY, Qin SD, Jin JR (2007) HBF4- catalyzed Biginelli reaction: one-pot synthesis of dihydropyrimidin-2(1H)-ones under solvent-free conditions. Catal Commun 8:123–126
Trichloroisocyanuric acid/EtOH: Bigdeli MA, Jafari S, Mahdavinia GH, Hazarkhani H (2007) Trichloroisocyanuric acid, a new and efficient catalyst for the synthesis of dihydropyrimidinones. Catal Commun 8:1641–1644
Cu(BF4)2 × xH2O/neat: Kamal A, Krishnaji T, Azhar MA (2007) Copper(II) tetrafluoroborate as a mild and efficient catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions. Catal Commun 8:1929–1933
Fe(CF3CO2)3 or Fe(OTf)3/sf: Adibi H, Samimi HA, Beygzadeh M (2007) Iron(III) trifluoroacetate and trifluoromethanesulfonate: recyclable lewis acid catalysts for one-pot synthesis of 3,4-dihydropyrimidinones or their sulfur analogues and 1,4-dihydropyridines via solvent-free Biginelli and Hantzsch condensation protocols. Catal Commun 8:2119–2124
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Kolosov, M.A., Orlov, V.D., Beloborodov, D.A. et al. A chemical placebo: NaCl as an effective, cheapest, non-acidic and greener catalyst for Biginelli-type 3,4-dihydropyrimidin-2(1H)-ones (-thiones) synthesis. Mol Divers 13, 5–25 (2009). https://doi.org/10.1007/s11030-008-9094-8
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DOI: https://doi.org/10.1007/s11030-008-9094-8