Specific phosphorylation of 5-ethyl-2′-deoxyuridine by herpes simplex virus-infected cells and incorporation into viral DNA

First-in-class pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones against leishmaniasis and tuberculosis: Rationale, in vitro, ex vivo studies and mechanistic insights

Pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones were synthesized, for the first time, from indole chalcones and 6-aminouracil, and their ability to inhibit leishmaniasis and tuberculosis (Tb) infections was evaluated. The in vitro antileishmanial activity against promastigotes of Leishmania donovani revealed exceptional activities of compounds 3, 12 and 13, with IC₅₀ values ranging from 10.23 ± 1.50 to 15.58 ± 1.67 µg/ml, which is better than the IC₅₀ value of the standard drug pentostam of 500 μg/ml. The selectivity of the compounds towards Leishmania parasites was evaluated via ex vivo studies in Swiss albino mice. The efficiency of these compounds against Tb infection was then evaluated using the in vitro anti-Tb microplate Alamar Blue assay. Five compounds, 3, 7, 8, 9 and 12, showed MIC₁₀₀ values against the Mycobacterium tuberculosis H₃₇ Rv strain at 25 µg/ml, and compound 20 yielded an MIC₁₀₀ value of 50 µg/ml. Molecular modelling of these compounds highlighted interactions with binding sites of dihydrofolate reductase, pteridine reductase and thymidylate kinase, thus establishing the rationale of their pharmacological activity against both pathogens, which is consistent with the in vitro results. From the above results, it is clear that compounds 3 and 12 are promising lead candidates for Leishmania and Mycobacterium infections and may be promising for coinfections.

Metal-free syntheses of new azocinesviaaddition reactions of enaminones with acenaphthoquinone followed by oxidative cleavages of the corresponding vicinal diols

A one-pot, clean and green procedure is described for the syntheses of new azocine derivatives via addition reactions of enaminones with acenaphthoquinone followed by periodic acid-mediated oxidative cleavages of the corresponding vicinal diols. Various derivatives of azocine were prepared and well characterized. The excellent yields, simple synthesis procedure, lack of a need to carry out any tedious work-up and column chromatography, metal-free catalysis, and mild reaction conditions are important features of this protocol.

One-pot metal-free periodic acid-mediated syntheses of azocine rings with high yields under mild reaction conditions via the addition reactions of enaminones and acenaphthoquinone.

TBHP-mediated oxidative synthesis of substituted pyrimido[4,5-d]pyrimidines from N-uracil amidines and methylarenes under metal free conditions

An efficient and operationally simple protocol has been demonstrated for the synthesis of 1,3,5,7-tetrasubstituted pyrimido[4,5-d]pyrimidines via TBHP-mediated direct oxidative coupling of N-uracil amidines and methylarenes under metal-free conditions. Due to the inherent stability of methylarenes compared to aldehydes, the presented synthetic protocol is adaptable to a broad substrate scope, is operationally simple, has no need for stringent protection in the whole preparation process, and has the potential to prepare valuable products that are currently inaccessible or challenging to prepare using conventional methods. It is a significantly important complement to the conventional synthetic methods. The reaction possesses an efficient tandem oxidation-imination-cyclization process.

Convenient One-Pot Four-Component Synthesis of 6,8-Disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones via a Triple Mannich Reaction

An efficient and simple one-pot four-component protocol has been developed and performed for the synthesis of 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones, involving a triple Mannich reaction of 6-amino-2-(ethylthio)pyrimidin-4(3H)-one, formaldehyde, primary amines, and alcohols. Secondary amines were also utilised instead of alcohols as Mannich nucleophiles, and a variety of functional groups and electronically varied reaction partners were tolerated. This one-pot reaction facilitated the generation of a library of pyrimido[4,5-d]pyrimidin-4(3H)-ones in very good to excellent yields. The regioselectivity of this reaction was investigated using atomic charge calculations, and spectroscopic data confirmed that the triple Mannich products were 6,8-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones rather than the isomeric 3,6-disubstituted-5,6,7,8-tetrahydropyrimido[4,5-d]pyrimidin-4(3H)-ones. The structures of all compounds synthesised using the triple Mannich reaction were confirmed via spectroscopic and elemental analyses. The reaction mechanism was studied and confirmed by isolation of the intermediate.

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

This review article summarizes the results of a long-term investigation of 5-alkoxymethyluracil analogues and is aimed, in particular, at methods of syntheses. Most of the presented compounds were synthesized in order to evaluate their biological activity, therefore, a brief survey of biological activity, especially antiviral, cytotoxic and antibacterial, is also reported.

Synthesis of some novel annulated pyrido[2,3-d]pyrimidines via stereoselective intramolecular hetero Diels-Alder reactions of 1-oxa-1,3-butadienes

Some novel annulated pyrido[2,3-d]pyrimidines 6 and 7 were synthesized stereoselectively by intramolecular hetero Diels-Alder reactions involving 1-oxa-1,3-butadienes.

Rapid and efficient synthesis of fused heterocyclic pyrimidines under ultrasonic irradiation

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.

Synthesis of 5,5′-(arylmethylene)bis(pyrimidinone) derivatives in aqueous media

The condensation and addition reactions of aromatic aldehydes and 4,6-dihydroxypyrimidine or 2,4-dihydroxy-6-aminopyrimidine in water in the presence of triethylbenzylammonium chloride (TEBAC) afford a one-pot synthesis of 5,5′-(arylmethylene)bis[6-hydroxypyrimidine-4(3H)-one]s and 5,5′-(arylmethylene)bis[6-aminopyrimidine-2,4 (1H,3H)-dione]s. These compounds were characterised by elemental analysis and IR and 1H NMR spectra and further confirmed by a single crystal X-ray diffraction analysis.

Synthesis of Some New Pyrazolo[1,5-a]Pyrimidines

Pyrazolo[1,5-a]pyrimidines were synthesised from the the reaction of β-diketone, β-keto ester, 1,2-disubstituted acrylonitrile or sodium (3-oxocycloalkylidene) methenolate. Elemental analysis, spectral data and alternative synthesis route elucidated structures of the newly synthesised compounds.

A new microwave-assisted synthetic approach to novel pyrimido[4,5-d]pyrimidines

An environmentally benign approach for the synthesis of novel 7-substituted 5-aryl-1H-pyrimido[4,5-d]pyrimidine-2,4-diones, using mineral supports for their catalytic role and as energy transfer media, is described. The methodology eliminates the usage of solvent during the reaction. The rate enhancement and high yield is attributed to the coupling of solvent-free conditions with microwaves. Further, the role of various supports is studied during the reaction and it is concluded that a MW-assisted basic alumina catalysed reaction is the best in terms of catalysis as well as reaction time and yield.Key words: microwave (MW) irradiation, SBT, pyrimido[4,5-d]pyrimidines, alumina, environmentally benign.

Regiospecific one-pot synthesis of pyrimido[4,5-d]pyrimidine derivatives in the solid state under microwave irradiations

Electron rich 6-[(dimethylamino)methylene]amino uracil 1, undergoes [4+2] cycloaddition reactions with various in situ generated glyoxylate imine and imine oxides 6 to provide novel pyrimido[4,5-d]pyrimidine derivatives of biological significance, after elimination of dimethylamine from the (1:1) cycloadducts and oxidative aromatisation. This procedure provides a convenient method for the direct synthesis of pyrimido[4,5-d]pyrimidines in excellent yields when carried out in the solid state and under microwave irradiations.