An efficient one-pot three-component synthesis of functionalized pyrimido[4,5-b]quinolines and indeno fused pyrido[2,3-d]pyrimidines in water

A simple, efficient, and high yielding one-pot protocol for the synthesis of pyrimido[4,5-b]quinolines and indeno[2′,1′:5,6]pyrido[2,3-d]pyrimidines has been developed by three-component domino coupling of 6-amino-1,3-dimethyluracil, aldehydes, and cyclic 1,3-diketones in ecofriendly solvent water promoted by PTSA. The protocol avoids the use of expensive catalysts, toxic solvents, and chromatographic separation. The generality and functional tolerance of this convergent and environmentally benign method is demonstrated.     

Nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a magnetically separable catalyst for green and efficient synthesis of functionalized pyrimido[4, 5-b]quinolines and indeno fused pyrido[2, 3-d]pyrimidines in water

The magnetic nanoparticles supported silica sulfuric acid was used as an efficient catalyst for the synthesis of pyrimido[4,5-b]quinolines and indeno fused pyrido[2,3-d]pyrimidines in water. The desired products were obtained in excellent yields. Fe3O4@SiO2-SO3H was readily recovered using an external magnet and could be reused several times without significant loss of reactivity.     

Novel ionic liquid supported on Fe3O4 nanoparticles as an efficient catalyst for the synthesis of new chromenes

An efficient procedure for the synthesis of new chromenes by the multicomponent reaction of aldehydes, 4‐hydroxycoumarin and 2‐hydroxynaphthalene‐1,4‐dione in the presence of an ionic liquid supported on Fe₃O₄ nanoparticles is described. The ionic liquid supported on Fe₃O₄ nanoparticles as a magnetic catalyst gives products in high yields. Significant features of this method are: short reaction times, excellent yields, green method and use of an effective catalyst that can be recovered and reused many times without loss of its catalytic activity.     

Post‐synthetic modification of IR-MOF‐3 as acidic-basic heterogeneous catalyst for one-pot synthesis of pyrimido[4,5-b]quinolones

Research on Chemical Intermediates - In this study, a modified IR-MOF-3 via a multi-step post-synthesis modification, namely IR-MOF-3-ILOAc-Fe(acac)3, was prepared as an ion-pair heterogeneous...     

Convenient synthesis of novel pyrimido[4,5-b][1,5]benzothiazepines

Reaction of 4,6-dichloropyrimidine-5-carbaldehyde with amines in chloroform gave 4-(substitutedamino)-6-chloro-pyrimidine-5-carbaldehydes derivatives at low temperature. Treatment of the latter products with 2-aminobenzenethiol in alkaline benzene and then in boiling acetonitrile gave a novel group of 11H-pyrimido[4,5-b][1,5]benzodiazepine derivatives. Structures of the products confirmed by ¹HNMR, IR, and mass spectra.     

Triethanolamine lactate-supported nanomagnetic cellulose: a green and efficient catalyst for the synthesis of pyrazolo[3,4-b]quinolines and theoretical study

Research on Chemical Intermediates - A novel nanomagnetic catalyst has been synthesized by immobilization of triethanolamine lactate cellulose with Fe3O4 NPs. The prepared catalyst has been used as...     

Synthesis of pyrimido[4,5-b]quinolines in the reaction of 6-aminopyrimidines with dimedone and benzaldehydes

The reaction of 6-aminopyrimidines 1a, b with dimedone ( 2 ) and p-substituted benzaldehydes 3a-d in ethanol afforded in all cases new regiospecific synthesis of tricyclic, linear 5-aryl-5,6,7,8,9,10-hexahydropyrimido[4,5-b]quinolines 4a-h in good yields. The linear structures and hence the regiospecificity of the reaction were established by nmr measurements.     

Magnetic nanoparticles Fe3O4-supported guanidine as an efficient nanocatalyst for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free conditions

Research on Chemical Intermediates - Here, the application of guanidine supported on magnetic nanoparticles Fe3O4 (MNPs-guanidine) as a novel magnetically separable base nanocatalyst is described....     

N-Bromosuccinimide as an efficient catalyst for the synthesis of indolo[2,3-b]quinolines

The use of N-bromosuccinimide as a catalyst promoted the synthesis of polycyclic indolo[2,3-b]quinoline derivatives in good to high yields in the reactions of various aryl amines with indole-3-carbaldehyde at room temperature under mild conditions.     

An efficient protocol for synthesis of novel polyheterocyclic chromeno pyrimido[1,2-b]indazolone derivatives using [Et3NH][HSO4] as a reusable catalyst under solvent-free conditions

A convenient and highly efficient method for the synthesis of novel polyheterocyclic chromeno pyrimido[1,2-b]indazolone derivatives via a three-component condensation of 1H-indazol-3-amine, aldehydes and 4-hydroxycoumarin catalyzed by Bronsted acid ionic liquid [Et₃NH][HSO₄] under solvent-free reaction conditions is presented. This ionic liquid is air and water stable and easy to prepare from amine and acid. The main advantages of this protocol includes short reaction time, excellent yield, easy work-up, operational simplicity, a wide range of functional group tolerance and column chromatography-free method. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields.     

Synthesis of a series of diaminobenzo[f]- and diaminobenzo[h]pyrimido[4,5-b]quinolines as 5-deaza tetracyclic nonclassical antifolates

A series of diaminobenzo[f]- and diaminobenzo[h]pyrimido[4,5-b]quinolines 1–11 were designed as 5-deaza tetracyclic nonclassical, lipophilic antifolates. The compounds were designed as conformationally semi-rigid and rigid analogs of 2,4-diamino-6-phenyl- 12 and 2,4-diamino-7-phenylpyrido[2,3-d]pyrimidines 13 and 14 . The target compounds were synthesized by cyclocondensation of chlorovinyl aldehydes obtained from appropriately substituted 1- or 2-tetralone, with 2,4,6-friaminopyrimidine. Compounds 1–11 were evaluated as inhibitors of P. carinii and T. gondii dihydrofolate reductases. These pathogens cause fatal opportunistic infections in AIDS patients. In addition, the selectivity of these agents was evaluated using rat liver dihydrofolate reductase as the mammalian source. In general the benzo[f]pyrimido[4,5-b]quinolines 1–5 were more potent than the corresponding benzo[h]pyrimido[4,5-b]quinoline analogues 6–11 against P. carinii and rat liver dihydrofolate reductase and were equipotent against T. gondii dihydrofolate reductase. Compounds 6–11 were moderately selective towards T. gondii dihydrofolate reductase with IC₅₀S in the 10⁻⁷ M range. In contrast analogues 1–5 lacked selectivity against P. carinii or T. gondii dihydrofolate reductase and were, in general, potent inhibitors of rat liver dihydrofolate reductase with IC₅₀S in the 10⁻⁸ M range. Analogues 1 and 4 were evaluated against a series of tumor cell lines in vitro and were found to have moderate antitumor activity (IC50 10⁻⁶ M). The structure activity/selectivity relationships suggest that benzo[f]pyrimido analogues 1–5 with the phenyl ring substitution in the “upper” portion of the tetracyclic ring are better accommodated within the rat liver (mammalian) dihydrofolate reductase and P. carinii dihydrofolate reductase active sites compared to the benzo[h]pyrimido analogues 6–11 which have the phenyl ring substitution in the “lower” portion of the tetracyclic ring. In contrast T. gondii dihydrofolate reductase does not discriminate between the isomers and binds to both series of compounds with similar affinities.     

Synthesis of some pyrimido[4′,5′:4,5]thieno[2,3-b]quinolines and related heterocycles

Several thieno[2,3-b]quinolines 6a-i have been synthesized. These compounds were used as key intermediates in the synthesis of oxazino[4′,5′:4,5]thieno[2,3-b]quinoline 8 , pyrimido[4′,5′:4,5]-thieno[2,3-b]quinolines 9–12 , triazino[4′,5′:4,5]thieno[2,3-b] quinolines 14 and imidazo[4′,5′:4,5]-thieno[2,3-b]quinolines 17 .     

Silica supported phosphomolybdic acid: an efficient heterogeneous catalyst for Friedlander synthesis of quinolines

Silica supported phosphomolybdic acid, an eco-friendly heterogeneous catalyst, has been found to be highly efficient for Friedlander synthesis of quinolines in excellent yields. A variety of ketones afford the quinolines smoothly. The catalyst can be easily recovered and reused.     

Pyrido[2,3-d]pyrimidines,II. One step synthesis of pyrido[2,3-d]pyrimidines and pyrimido[4,5-b]quinolines from 6-amino uracils

Summary Reduction of 6-azidouracils2 with hydrogen palladium or sodium dithionite afforded the corresponding 6-aminouracils5 which could also be obtained by reaction of2 with triphenylphosphanevia phosphazenes and subsequent hydrolysis (Staudinger reaction). The use of trimethylphosphite instead of phosphanes yields with2b the expected trimethoxyphosphazene3c, whereas2a reacts to the phosphonoaminopyrimidine4. The syntheses of 5-hydroxy pyrido[2,3-d]pryimidine-2,4,7-triones6, pyrido[2,3-d]pyrimidine-2,4,5-triones8, cyclopenta[e]pyrido[2,3-d]pyrimidin-2,4,5-triones7a,c, and tetrahydro-pyrimido[4,5-b]quinolin-2,4,5-triones7b,d by condensation of 6-aminouracils5 with malonates, ethylaceto/benzoylacetate, ethyl 2-oxocyclopentanecarboxylate and ethyl 2-oxocyclohexanecarboxylate, respectively, are described.

---

Pyrido[2,3-d]pyrimidine, 2. Mitt. Einstufige Synthese von Pyrido[2,3-d]pyrimidinen und Pyrimido[4,5-b]chinolinen aus 6-Aminouracilen

Zusammenfassung Reduktion der 6-Azidouracile2 mit Wasserstoff/Palladium oder Natriumdithionit ergibt die entsprechenden 6-Aminouracile5, die auch durch Reaktion von2 mit Triphenylphosphin und anschließende Hydrolyse erhalten werden können (Staudinger-Reaktion). Die Verwendung von Trimethylphosphit anstelle von von Trimethylphosphin ergibt mit2b das erwartete Trimethoxyphosphazin3c, während2a zum Phosphonoaminopyrimidin4 reagiert. Die Synthesen der 5-Hydroxy-pyrido[2,3-d]pyrimidin-2,4,7-trione6, der Pyrido[2,3-d]pyrimidin-2,4,5-trione8, der Cyclopenta[e]pyrido[2,3-d]pyrimidin-2,4,5-trione7a,c und der Tetrahydro-pyrimido[4,5-b]chinolin-2,4,5-trione7b,d durch Kondensation der 6-Aminouracile5 mit Malonat, Acetat, Ethyl-2-oxocyclopentancarboxylat und Ethylcyclohexancarboxylat werden beschrieben.

     

An efficient and regioselective one-pot multi-component synthesis of pyrimido[4,5-d]pyrimidine derivatives in water

Pyrimido[4,5-d]pyrimidine derivatives 4 have been prepared in an efficient and regioselective manner in water via multi-component reaction of isothiocyanate 1, aromatic aldehyde 2, N,N-dimethyl-6-amino uracil 3 in the presence of p-toluenesulfonic acid (p-TSA) as a Lewis acid catalyst.