Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.
Scientific Reports volume 13, Article number: 16501 (2023 ) Cite this article Formamidinium Acetate
![Multicomponent synthesis of pyrimido[4,5-b] quinolines over a carbocationic catalytic system | Scientific Reports](http://cdn.globalso.com/hschemraw/Formamidine-acetate.jpg)
Trityl chloride (TrCl) was efficiently used as a neutral catalyst for the multicomponent cyclization reaction of an aldehyde with dimedone and 6-amino-1,3-dimethyluracil for the preparation of pyrimido[4,5-b] quinolines in chloroform under reflux condition.
Organic catalysts with high stability, insensitivity to moisture and oxygen, specific molecular structure, low toxicity and the absence of metal in their structure are notable for the catalyze of the organic reactions1,2.
Recently, the application of trityl chloride as an organic catalyst has been considered in organic synthesis due to some advantages such as cheapness and commercially available. Also, neutral and mild reaction condition in terms of temperature and pressure is another benefits for trityl chloride as a catalyst3.
Trityl chloride was applied as an organic catalyst for the preparation of various organic compounds such as bis(indolyl) methanes3, N-sulfonyl imines4, 1-amidoalkyl-2-naphtols5, 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-ones6, 1-thioamido-alkyl-2-naphthols, 1-carbamato-alkyl-2-naphthols7, 3-(2,6-diarylpyridin-4-yl)-1H-indoles, 2,4,6-triarylpyridines8, pyranopyrazoles9, gem-bisamides10, 1,2,4,5-tetrasubstitutedimidazoles11, and α,α′-bis(arylidene)cycloalkanones12.
Pyrimido[4,5-b]quinolones are important compounds in medicinal chemistry due to some biological properties such as antifungal13, antimalarial14, anticancer15,16, antiviral17, antihistaminic18, anti-oxidant, anti-microbial19, and anti-inflammatory activities19,20. The one pot multi-component synthesis of pyrimido[4,5-b]quinolones by the reaction of aldehyde with dimedone and 6-amino-1,3-dimethyluracil is an important method for the preparation of these compounds19. Multi-component reactions are notable for the chemists due to prepare of the target product in one step without the produce of side products. High atomic economy, high yields, short reaction times, saving energy, reaction times, materials and solvents and compliance with green chemistry protocols are some important advantages of these reactions21,22,23,24,25,26.
Various catalysts were used in the multi-component synthesis of pyrimido[4,5-b]quinolines such as [TSSECM]27, SBA-15/PrN(CH2PO3H2)228, Nano-[Fe3O4@SiO2/N-propyl-1-(thiophen-2-yl)ethanimine][ZnCl2]29, [H2-DABCO][ClO4]230, nano-[Fe3O4@- SiO2@R-NHMe2][H2PO4]31, N,N-diethyl-N-sulfoethanaminium chloride32, Fe3O4@Cellulose sulfuric acid33, [bmim]Br34, nanocrystalline MgO35, glycolic acid-supported cobalt ferrite36, Agar-entrapped sulfonated DABCO37, [C4(DABCO)2]·2OH38, DABCO39, Nano‑[Cu‑4C3NSP](Cl)240, and Cellulose sulfuric acid41, nano-[Fe3O4@SiO2@BDIL]42 and Cs2.3H0.7PW10Mo2O4043. Most of the reported methods are performed by acidic or basic catalysts. In the presented work, the preparation of pyrimido[4,5-b]quinolines was reported in the presence of trityl chloride (TrCl) as a neutral and cheap compound which is commercially available. This method was carried out under mild reaction condition. In the presented work, it is interesting that, the reaction was carried out using carbocationic catalytic system.
In continues to our investigation on the catalytic application of carbocationic system to carry out the organic reactions, we have used of trityl chloride (TrCl) as a neutral catalyst for the preparation of pyrimido[4,5-b] quinolines by the multi component reaction of aromatic aldehydes with dimedone and 6-amino-1,3-dimethyluracil (Fig. 1).
The preparation of pyrimido[4,5-b]quinolines.
In the first step, to find the best reaction condition, the reaction of 2, 4-dichlorobenzaldehyde with dimedone and 6-amino-1,3-dimethyluracil was selected as a model reaction and kinds of catalysts, catalyst amounts and temperature were studied on this reaction. Also, the model reaction was carried out in various solvents such as chloroform, ethanol, ethyl acetate, n-hexane, acetone, dichloromethane and acetonitrile in comparison with solvent-free condition. According that, the best result was obtained using 10 mol % of trityl chloride as a catalyst in chloroform under reflux condition (Table 1).
The catalytic effect of trityl chloride has been compared with its other derivatives such as trityl alcohol, monomethoxytrityl chloride and dimethoxytrityl chloride on the three-component reaction of dimedone, 6-amino-1,3-dimethyluracil and 2, 4-dichlorobenzaldehyde. In this study, trityl chloride showed the best catalytic performance and in the presence of this catalyst, the shortest reaction time and the highest efficiency for the desired product were obtained. The presence of electron-donating groups on the trityl chloride ring stabilizes the carbocation and reduces its acid strength. The order of stability and acid strength of some carbocations of the trityl derivatives is specified in Fig. 244.
The comparison of trityl carbocation derivatives with each other in term of acidity and stability.
Turn-over frequency (TOF) and Turn-over number (TON) of TrCl in comparison with other derivatives of TrCl such as monomethoxytrityl chloride and dimethoxytrityl chloride on the three-component reaction of dimedone, 6-amino-1,3-dimethyluracil and 2, 4-dichlorobenzaldehyde to show the superiority of TrCl as a catalyst for the synthesis of pyrimido[4,5-b]quinolines were given in Fig. 3. As it is shown in Fig. 3, indicates that TrCl is more efficient than the other catalysts in terms of TOF and TON for the preparation of this compounds.
Catalytic activity of various triarylmethyl chlorides on the reaction of 2, 4-dichlorobenzaldehyde with dimedone and 6-amino-1,3-dimethyluracil in chloroform under reflux condition.
After the optimization of the reaction condition, various aromatic aldehydes containing releasing or withdrawing groups and halogen on their ring, were reacted with dimedone and 6-amino-1,3-dimethyluracil to give pyrimido[4,5-b]quinolines derivatives. All products were obtained in high yields and short reaction times (Table 2).
To discuss the mechanism for the preparation of the pyrimido[4,5-b]quinolines compounds in the presence of carbocationic catalytic system under neutral media, as it is reported on previous literature3,4,5,6,7,8,9,10,11,12, firstly, aldehyde was converted to activated forms (I and II) by the reaction with trityl cation which in situ generated from trityl chloride. Then, dimedone in enole form reacted with activated forms of aldehyde (I and II) to give (III) which could be converted to (IV) and (V). Then, 6-amino-1,3-dimethyluracil was reacted with intermediate (V) to prepare (VI). Lastly, by the intramolecular nucleophilic attack in intermediate (VI), the expected product was synthesized after removing of one molecule of H2O. Trityl chloride was regenerated by the reaction of trytil alcohol with (VII) and removing of one molecule of H2O (Fig. 4).
The proposed mechanism for the preparation of pyrimido[4,5-b]quinolines.
All chemicals were purchased from Merck or Fluka Chemical Companies. The known products were identified by comparison of their melting points and spectral data with those reported in the literature. Progress of the reactions was monitored by TLC using silica gel SIL G/UV 254 plates. The 1H NMR (250 MHz) and 13C NMR (62.5 MHz) were recorded on a Bruker Avance DPX FT-NMR spectrometer (δ in ppm). Melting points were recorded on a Büchi B-545 apparatus in open capillary tubes.
In a round-bottomed flask which connected to a reflux condenser, aromatic aldehydes (1 mmol), dimedone (1 mmol, 0.140 g), 6-amino-1,3-dimethyluracil (1 mmol, 0.155 g) and trityl chloride (TrCl) (10 mol %, 0.0278 g) as a catalyst were added and stirred in chloroform (10 mL) as a solvent under reflux condition for appropriate time (Table 2). After completion of the reaction as monitored by TLC, the solvent was removed and finally, the desired product was purified by the recrystallization in aqueous ethanol (70%).
White Solid; M.p: 350–355 °C;IR (KBr, cm−1): 3281, 3224, 3094, 2960, 1702, 1641, 753, 538; 1H NMR (250 MHz, DMSO-d6): δ 0.85 (s, 3H), 1.00 (s, 3H), 1.93 (d, J = 16 Hz, 1H), 2.16 (d, J = 16 Hz, 1H), 2.52 (s, 2H), 3.01 (s, 3H), 3.42 (s, 3H), 5.15 (s, 1H), 7.05 (d, J = 6.75 Hz, 1H), 7.14 (d, J = 7.25 Hz, 2H), 7.29 (s, 1H), 8.97 (s, 1H); 13C-NMR (DMSO-d6, 62.5 MHz): δ 26.7, 27.9, 29.5, 30.6, 32.3, 34.1, 50.5, 89.9, 111.2, 126.7, 127.7, 129.5, 132.4, 133.0, 143.8, 144.5, 150.2, 150.9, 160.8, 194.7.
White Solid; M.p: 340 °C;IR (KBr, cm−1): 3278, 3218, 3093, 2950, 2875, 1705, 1661, 1643, 1610, 1495,1379, 1211, 1045,755, 508; 1H NMR (250 MHz, DMSO-d6): δ 0.85 (s, 3H), 1.00 (s, 3H), 1.94 (d, J = 16.25 Hz, 1H), 2.16 (d, J = 16 Hz, 1H), 2.49 (d, J = 12 Hz, 2H), 3.01(s, 3H), 3.41 (s, 3H), 5.10 (s, 1H), 7.22 (d, J = 8 Hz, 2H), 7.30 (s, 1H), 8.98 (s, 1H); 13C-NMR (DMSO-d6, 62.5 MHz): δ 26.8, 27.9, 29.4, 30.6, 32.3, 34.0, 49.8, 50.4, 89.5, 110.8, 126.,9 128.7, 131.2, 133.6, 134.0, 143.0, 144.6,150.5,150.9,160.9,194.8.
White Solid; M.p: 332–335 °C;IR (KBr, cm−1): 3281, 3220, 3090, 2961, 1702, 1662, 1603, 1507, 1380, 962, 756; 1H NMR (250 MHz, DMSO-d6): δ 0.86 (s, 3H), 1.01 (s, 3H), 1.99 (d, J = 16 Hz, 1H), 2.16 (s, 3H), 2.18 (d, J = 16 Hz, 1H), 2.50 (d, J = 12.5 Hz, 2H), 3.05 (s, 3H), 3.42 (s, 3H), 4.80 (s, 1H), 6.94 (d, J = 7.5 Hz, 1H), 7.07 (d, J = 7.5 Hz, 2H), 8.94 (s, 1H); 13C-NMR (DMSO-d6, 62.5 MHz): δ 21.0, 26.9, 28.0, 29.5, 30.5, 32.5, 33.7, 50.5, 90.7, 112.2, 127.9, 128.6, 135.2, 143.9, 144.1, 149.7, 150.9, 161.1, 194.9.
White Solid; M.p: 307–309 °C; 1H NMR (250 MHz, DMSO-d6): δ 0.86 (s, 3H), 1.01 (s, 3H), 2.00 (d, J = 16.00 Hz, 1H), 2.18 (d, J = 16.00 Hz, 1H), 2.48–2.54 (m, 2H), 3.06 (s, 3H), 3.41 (s, 3H), 3.64 (s, 3H), 4.78 (s, 1H), 6.70 (d, J = 8.00 Hz, 1H), 7.09 (d, J = 7.75 Hz, 1H), 8.94(s, 1H); 13C-NMR (DMSO-d6, 62.5 MHz): δ 26.9, 28.0, 29.5, 30.6, 32.5, 33.3, 44.7, 50.5, 55.3, 90.8, 112.3, 113.5, 125.2, 129.0, 139.1, 144.0, 149.6, 151.0, 157.8, 161.1, 195.0, 202.2.
White Solid; M.p: 298–300 °C; 1H NMR (250 MHz, DMSO-d6): δ 0.91 (s, 3H), 1.02 (s, 3H), 2.04 (d, J = 15.75 Hz, 1H), 2.23 (d, J = 15.75 Hz, 1H), 2.57 (d, J = 8.75 Hz, 2H), 3.08 (s, 3H), 3.67 (s, 3H), 4.96 (s, 1H), 6.55–6.64 (m, 3H), 9.09 (s, 1H), 9.15(s, 1H); 13C-NMR (DMSO-d6, 62.5 MHz): δ 27.0, 28.3, 29.4, 30.8, 32.5, 50.3, 55.9, 110.5, 119.6, 120.9, 134.3, 151.4, 196.0.
In summary, TrCl was used as a homogeneous organocatalyst for the synthesis of pyrimido[4,5-b]quinolines derivatives in neutral condition. The products were prepared in high yields and short reaction times. The low cost of trityl choride, commercially availability of the catalyst, short reaction times and the avoidance of harsh acidic conditions are important advantages of this work.
All data generated or analysed during this study are included in this published article (and its Supplementary Information files).
Pandey, J., Anand, N. & Tripathi, R. P. L-Proline catalyzed multicomponent reaction of 3,4-dihydro-(2H)-pyran, urea/thiourea, and aldehydes: Diastereoselective synthesis of hexahydropyrano pyrimidinones (thiones). Tetrahedron 65, 9350–9356 (2009).
Chandrasekhar, S., Johny, K. & Reddy, C. R. Proline–threonine dipeptide as an organocatalyst for the direct asymmetric aldol reaction. Tetrahedron Asymmetry 20, 1742–1745 (2009).
Khalafi-Nezhad, A. et al. Trityl chloride as a novel and efficient organic catalyst for room temperature preparation of bis (indolyl) methanes under solvent-free conditions in neutral media. Synthesis 4, 617–621 (2008).
Khalafi-Nezhad, A. et al. Triarylmethyl chlorides as novel, efficient, and mild organic catalysts for the synthesis of N-sulfonyl imines under neutral conditions. Can. J. Chem. 86, 456–461 (2008).
Khazaei, A. et al. Trityl chloride as an efficient organic catalyst for the synthesis of 1-amidoalkyl-2-naphtols in neutral media at room temperature. Appl. Catal. A Gen. 386, 179–187 (2010).
Khazaei, A. et al. Organocatalyst trityl chloride efficiently promoted the solvent-free synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-ones by in situ formation of carbocationic system in neutral media. Catal. Commun. 20, 54–57 (2012).
Khazaei, A. et al. Discovery of an in situ carbocationic system using trityl chloride as a homogeneous organocatalyst for the solvent-free condensation of β-naphthol with aldehydes and amides/thioamides/alkyl carbamates in neutral media. Tetrahedron 69, 212–218 (2013).
Moosavi-Zare, A. R., Zolfigol, M. A. & Rezanejad, Z. Trityl chloride promoted the synthesis of 3-(2,6-diarylpyridin-4-yl)-1H-indoles and 2,4,6-triarylpyridines by in situ generation of trityl carbocation and anomeric based oxidation in neutral media. Can. J. Chem. 94, 626–630 (2016).
Moosavi-Zare, A. R., Zolfigol, M. A. & Mousavi-Tashar, A. Synthesis of pyranopyrazole derivatives by in situ generation of trityl carbocation under mild and neutral media. Res. Chem. Intermed. 42, 7305–7312 (2016).
Moosavi-Zare, A. R., Goudarziafshar, H., Jalilian, Z. & Hajilouie, Z. The synthesis of gem-bisamides using a carbocationic catalytic system in neutral media. Org. Prep. Proced. Int. 54, 440–448 (2022).
Moosavi-Zare, A. R., Asgari, Z., Zare, A., Zolfigol, M. A. & Shekouhy, M. One pot synthesis of 1, 2, 4, 5-tetrasubstituted-imidazoles catalyzed by trityl chloride in neutral media. RSC Adv. 4, 60636–60639 (2014).
Zare, A., Merajoddin, M., Hasaninejad, A., Moosavi-Zare, A. R. & Khakyzadeh, V. Study of in situ generation of carbocationic system from trityl chloride (Ph3CCl) which efficiently catalyzed cross-aldol condensation reaction. C. R. Chimie 16, 380–384 (2013).
Drabczynska, A. et al. Phenylethyl-substituted pyrimido[2,1-f]purinediones and related compounds: Structure–activity relationships as adenosine A1 and A2A receptor ligands. Bioorg. Med. Chem. 15, 6956–6974 (2007).
Joshi, A. A. & Viswanathan, C. L. Recent developments in antimalarial drug discovery. Agents Med. Chem. https://doi.org/10.2174/187152106774755626 (2006).
Valderrama, J. A. et al. Studies on quinones. Part 44: Novel angucyclinone N-heterocyclic analogues endowed with antitumoral activity. Bioorg. Med. Chem. 16, 10172–10181 (2008).
Alqasoumi, S. I., Al-Taweel, A. M., Alafeefy, A. M., Noaman, E. & Ghorab, M. M. Novel quinolines and pyrimido [4, 5-b] quinolines bearing biologically active sulfonamide moiety as a new class of antitumor agents. Eur. J. Med. Chem. 45, 738–744 (2010).
Nair, V., Chi, G., Shu, Q., Julander, J. & Smee, D. F. A heterocyclic molecule with significant activity against dengue virus. Bioorg. Med. Chem. Lett. 19, 1425–1427 (2009).
CAS PubMed PubMed Central Google Scholar
Alagarsamy, V. Synthesis and pharmacological investigation of some novel 2-methyl-3-(substituted methylamino)-(3H)-quinazolin-4-ones as histamine H1-receptor blockers. Pharmazie 59, 753–755 (2004).
El-Gazzar, A. B. A., Hafez, H. N. & Nawwar, G. A. M. New acyclic nucleosides analogues as potential analgesic, anti-inflammatory, anti-oxidant and anti-microbial derived from pyrimido [4, 5-b] quinolones. Eur. J. Med. Chem. 44, 1427–1436 (2009).
Alagarsamy, V. et al. Synthesis and pharmacological investigation of some novel 2-phenyl-3-(substituted methyl amino) quinazolin-4 (3H)-ones as H1-receptor blockers. Pharmazie 57, 306–307 (2002).
Baghernejad, B. & Harzevili, M. R. Nano-cerium oxide/aluminum oxide: An efficient and useful catalyst for the synthesis of tetrahydro[a]xanthenes-11-one derivatives. Chem. Methodol. 5, 90–95 (2021).
Moosavi-Zare, A. R., Goudarziafshar, H., Jalilian, Z. & Hosseinabadi, F. Efficient pseudo-six-component synthesis of tetrahydro-pyrazolopyridines using [Zn-2BSMP]Cl2. Chem. Methodol. 6, 571–581 (2022).
Abedini, E. & Shaterian, H. R. L-Leucine supported on silica gel encapsulating γ-Fe2O3 nanoparticles: A new recoverable magnetic catalyst for preparation of 1, 3-thiazole derivatives. Eurasian Chem. Commun. 5, 228–245 (2023).
Baghernejad, B. & Taromsari, S. M. H. Aqueous media preparation of 2-amino-4H-benzopyran derivatives using cerium oxide nanoparticles as a recyclable catalyst. Asian J. Green Chem. 6, 194–202 (2022).
Muhiebes, R. M., Fatolahi, L. & Sajjadifar, S. L-proline catalyzed multicomponent reaction for simple and efficient synthesis of tetrahydropyridines derivatives. Asian J. Green Chem. 7, 121–131 (2023).
Deb, M. L., Borpatra, P. J. & Baruah, P. K. A one-pot catalyst/external oxidant/solvent-free cascade approach to pyrimidines via a 1,5-hydride transfer. Green Chem. 21, 69–74 (2019).
Zare, A., Dianat, M. & Eskandari, M. M. A novel organic–inorganic hybrid material: production, characterization and catalytic performance for the reaction of arylaldehydes, dimedone and 6-amino-1,3-dimethyluracil. New J. Chem. 44, 4736–4743 (2020).
Jalili, F., Zarei, M., Zolfigol, M. A., Rostamnia, S. & Moosavi-Zare, A. R. SBA-15/PrN(CH2PO3H2)2 as a novel and efficient mesoporous solid acid catalyst with phosphorous acid tags and its application on the synthesis of new pyrimido[4,5-b]quinolones and pyrido[2,3-d]pyrimidines via anomeric based oxidation. Microporous Mesoporous Mater. 294, 109865–109897 (2020).
Esmaili, S., Moosavi-Zare, A. R. & Khazaei, A. Nano-[Fe3O4@SiO2/N-propyl-1-(thiophen-2-yl)ethanimine][ZnCl2] as a nano magnetite Schiff base complex and heterogeneous catalyst for the synthesis of pyrimido[4,5-b]quinolones. RSC Adv. 12, 5386–5394 (2022).
ADS CAS PubMed PubMed Central Google Scholar
Shirini, F., Langarudi, M. S. N., Daneshvar, N., Jamasbi, N. & Irankhah-Khanghah, M. Preparation and characterization of [H2-DABCO][ClO4]2 as a new member of DABCO-based ionic liquids for the synthesis of pyrimido[4,5-b]-quinoline and pyrimido[4,5-d]pyrimidine derivatives. J. Mol. Struct. 1161, 366–382 (2018).
Zare, A., Lotfifar, N. & Dianat, M. Preparation, characterization and application of nano-[Fe3O4@-SiO2@R-NHMe2][H2PO4] as a novel magnetically recoverable catalyst for the synthesis of pyrimido[4,5-b]quinolones. J. Mol. Struct. 1211, 128030 (2020).
Zare, A. & Dianat, M. A highly efficient and green approach for the synthesis of pyrimido[4,5-b]quinolines using N, N-diethyl-N-sulfoethanaminium chloride. Z. Naturforsch. 76, 85–90 (2021).
Osanlou, F., Nemati, F. & Sabaqian, S. An eco-friendly and magnetized biopolymer cellulose-based heterogeneous acid catalyst for facile synthesis of functionalized pyrimido[4,5-b]quinolines and indeno fused pyrido[2,3-d]pyrimidines in water. Res. Chem. Intermed. 43, 2159–2174 (2017).
Shi, D.-Q. et al. An Efficient synthesis of pyrimido[4,5-b]quinoline and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives via multicomponent reactions in ionic liquid. J. Heterocyclic Chem. 45, 693–702 (2008).
Rad, A. M. & Mokhtary, M. Efficient one-pot synthesis of pyrido[2,3-d]pyrimidines catalyzed by nanocrystalline MgO in water. Int. Nano Lett. 5, 109–123 (2015).
Gholami, A., Mokhtary, M. & Nikpassand, M. Glycolic acid-supported cobalt ferrite-catalyzed one-pot synthesis of pyrimido[4,5-b]quinoline and indenopyrido[2,3-d]pyrimidine derivatives. Appl. Organomet Chem. 34, e6007 (2020).
Moghaddampour, I. M., Shirini, F. & Langarudi, M. S. N. Agar-entrapped sulfonated DABCO: Agelly acidic catalyst for the acceleration of one-pot synthesis of 1,2,4-triazoloquinazolinone and some pyrimidine derivatives. J. Mol. Struct. 1226, 129336 (2021).
Jolodar, O. G., Shirini, F. & Seddighi, M. Efficient synthesis of pyrano[2,3-d]pyrimidinone and pyrido[2,3-d]pyrimidine derivatives in presence of novel basic ionic liquid catalyst. Chin. J. Catal. 38, 1245–1251 (2017).
Esmaili, S., Moosavi-Zare, A. R., Khazaei, A. & Najafi, Z. The synthesis of novel pyrimido[4,5-b] quinolines containing benzyloxy and 1,2,3-triazole moieties by DABCO as a basic catalys. ACS Omega 7, 45314–45324 (2022).
CAS PubMed PubMed Central Google Scholar
Moosavi-Zare, A. R., Goudarziafshar, H. & Bahrami, Z. Nano-[Cu-4C3NSP](Cl)2 as a new catalyst for the preparation of pyrimido[4,5-b]quinoline derivatives. Res. Chem. Intermed. 49, 507–523 (2023).
Azimi, S. C. Cellulose sulfuric acid catalyzed multicomponent reaction for efficient synthesis of pyrimido and pyrazolo[4,5-b]quinolines under solvent-free conditions. Iran. J. Catal. 4, 113–120 (2014).
Zare, A. & Barzegar, M. Dicationic ionic liquid grafted with silica-coated nano-Fe3O4 as a novel and efficient catalyst for the preparation of uracil-containing heterocycles. Res. Chem. Intermed. 46, 3727–3740 (2020).
Khillare, K. R., Aher, D. S., Chavan, L. D. & Shankarwar, S. G. Cesium salt of 2-molybdo-10-tungstophosphoric acid as an efficient and reusable catalyst for the synthesis of uracil derivatives via a green route. RSC Adv. 11, 33980–33989 (2021).
ADS CAS PubMed PubMed Central Google Scholar
Naidu, V. R., Ni, S. & Franzen, J. The carbocation: A forgotten Lewis acid catalyst. ChemCatChem 7, 1896–1905 (2015).
Department of Chemical Engineering, Hamedan University of Technology, Hamedan, 65155, Iran
Ahmad Reza Moosavi-Zare & Raha Najafi
You can also search for this author in PubMed Google Scholar
You can also search for this author in PubMed Google Scholar
A.R.M.-Z. defined the research project and wrote the article. R.N. has done relevant exprimental and do the identification of products.
Correspondence to Ahmad Reza Moosavi-Zare.
The authors declare no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Moosavi-Zare, A.R., Najafi, R. Multicomponent synthesis of pyrimido[4,5-b] quinolines over a carbocationic catalytic system. Sci Rep 13, 16501 (2023). https://doi.org/10.1038/s41598-023-43793-5
DOI: https://doi.org/10.1038/s41598-023-43793-5
Anyone you share the following link with will be able to read this content:
Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
Scientific Reports (Sci Rep) ISSN 2045-2322 (online)
![Multicomponent synthesis of pyrimido[4,5-b] quinolines over a carbocationic catalytic system | Scientific Reports](http://cdn.globalso.com/hschemraw/CAS-3473-63-0.jpg)
Mdl Mfcd00012866 Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.