An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium-catalyzed multi-component domino reaction.
ABSTRACT: Various novel pyrano [2,3-d]pyrimidines 5 and furopyrano [2,3-d]pyrimidines 7 were synthesized in 80-99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III) chloride. The reaction also proceeds in aqueous media without using any catalyst, but the yield is comparatively less (65-70%).
Project description:Pyrano[2,3-c]pyrazoles are obtained via mixing ethyl acetoacetate, hydrazine hydrate, aldehydes or ketones and malononitrile in the absence of solvent. These same products were also obtained by reacting arylidenemalononitriles 3 with 3-methyl-2-pyrazolin-5-ones. NOE difference experiments confirmed that these products exist solely in the 2H form. Similar treatments of 3-amino-2-pyrazolin-5-one with arylidene-malononitrile afforded adduct 6. Similarly mixing ethyl cyanoacetate, hydrazine hydrate, aldehydes, with malononitrile gave the same product 6. A novel synthesis of 4-oxo-4H-pyrano[2,3-c]pyrazole (8) could be achieved via reacting 3-methyl-2-pyrazolin-5-one with a mixture of cyanoacetic acid and acetic anhydride. Similar treatment of 3-aminopyrazole 11 with the benzylidene-malononitrile produced the pyrazolo[2,3-a]pyrimidines 12a,b.
Project description:A straightforward and efficient method for the synthesis of pyrano[2,3-d]pyrimidine diones derivatives from the reaction of barbituric acid, malononitrile and various aromatic aldehydes using SBA-Pr-SO3H as a nanocatalyst is reported.Reactions proceed with high efficiency under solvent free conditions. Urease inhibitory activity of pyrano[2,3-d]pyrimidine diones derivatives were tested against Jack bean urease using phenol red method. Three compounds of 4a, 4d and 4l were not active in urease inhibition test, but compound 4a displayed slight urease activation properties. Compounds 4b, 4k, 4f, 4e, 4j, 4g and 4c with hydrophobic substitutes on phenyl ring, showed good inhibitory activity (19.45-279.14 ?M).The compounds with electron donating group and higher hydrophobic interaction with active site of enzyme prevents hydrolysis of substrate. Electron withdrawing groups such as nitro at different position and meta-methoxy reduced urease inhibitory activity. Substitution of both hydrogen of barbituric acid with methyl group will convert inhibitor to activator.
Project description:Capillasterin A (<b>1</b>), a novel pyrano[2,3-f]chromene, together with seven known naphthopyrones including comaparvin (<b>2</b>), TMC-256C1 (<b>3</b>), 6-methoxycomaparvin-5- methyl ether (<b>4</b>), 5,8-dihydroxy-6-methoxy-2-propyl-4H-naphtho[2,3-b]pyran-4-one (<b>5</b>), 5,8-dihydroxy-6,10-dimethoxy-2-propyl-4H-naphtho[2,3-b]pyran-4-one (<b>6</b>), TMC-256A1 (<b>7</b>) and 6-methoxycomaparvin (<b>8</b>) were isolated from an EtOH/H?O extract from the Australian crinoid <i>Capillaster multiradiatus</i>. The structures of all the compounds were determined by detailed spectroscopic (1D/2D NMR and MS) data analysis. This is the first report of a natural product that contains the pyrano[2,3-f]chromene skeleton. Compounds <b>2</b>?<b>6</b> were observed to display moderate inhibition of in vitro HIV-1 replication in a T cell line with EC<sub>50</sub> values ranging from 7.5 to 25.5 µM without concomitant cytotoxicity.
Project description:Antibiotic resistance is a global crisis that threatens our ability to treat bacterial infections, such as tuberculosis, caused by Mycobacterium tuberculosis Of the 10 million cases of tuberculosis in 2017, approximately 19% of new cases and 43% of previously treated cases were caused by strains of M. tuberculosis resistant to at least one frontline antibiotic. There is a clear need for new therapies that target these genetically resistant strains. Here, we report the discovery of a new series of antimycobacterial compounds, 4-amino-thieno[2,3-d]pyrimidines, that potently inhibit the growth of M. tuberculosis To elucidate the mechanism by which these compounds inhibit M. tuberculosis, we selected for mutants resistant to a representative 4-amino-thieno[2,3-d]pyrimidine and sequenced these strains to identify the mutations that confer resistance. We isolated a total of 12 resistant mutants, each of which harbored a nonsynonymous mutation in the gene qcrB, which encodes a subunit of the electron transport chain (ETC) enzyme cytochrome bc 1 oxidoreductase, leading us to hypothesize that 4-amino-thieno[2,3-d]pyrimidines target this enzyme complex. We found that addition of 4-amino-thieno[2,3-d]pyrimidines to M. tuberculosis cultures resulted in a decrease in ATP levels, supporting our model that these compounds inhibit the M. tuberculosis ETC. Furthermore, 4-amino-thieno[2,3-d]pyrimidines had enhanced activity against a mutant of M. tuberculosis deficient in cytochrome bd oxidase, which is a hallmark of cytochrome bc 1 inhibitors. Therefore, 4-amino-thieno[2,3-d]pyrimidines represent a novel series of QcrB inhibitors that build on the growing number of chemical scaffolds that are able to inhibit the mycobacterial cytochrome bc 1 complex.IMPORTANCE The global tuberculosis (TB) epidemic has been exacerbated by the rise in drug-resistant TB cases worldwide. To tackle this crisis, it is necessary to identify new vulnerable drug targets in Mycobacterium tuberculosis, the causative agent of TB, and develop compounds that can inhibit the bacterium through novel mechanisms of action. The QcrB subunit of the electron transport chain enzyme cytochrome bc 1 has recently been validated to be a potential drug target. In the current work, we report the discovery of a new class of QcrB inhibitors, 4-amino-thieno[2,3-d]pyrimidines, that potently inhibit M. tuberculosis growth in vitro These compounds are chemically distinct from previously reported QcrB inhibitors, and therefore, 4-amino-thieno[2,3-d]pyrimidines represent a new scaffold that can be exploited to inhibit this drug target.
Project description:In this study, a multicomponent reaction involving carbohydrates, ?-dicarbonyl compounds, and malononitrile was disclosed to synthesize a new class of polyhydroxy compounds incorporating pyrano[2,3-d]pyrimidine, pyrido[2,3-d]pyrimidine and chromene heterocycles under mild conditions. For the synthesis of this class of compounds, glucose, galactose, arabinose, maltose, and lactose were used as aldehyde component in the reaction with barbituric acid and malononitrile to produce pyrano[2,3-d]pyrimidine derivatives. By use of 1,3-cyclohexanedione instead of barbituric acid, chromene derivatives incorporating carbohydrate moieties were obtained. Also, the four-component condensation reaction between d-glucosamine, aldehyde, malononitrile, and barbituric acid was efficiently provided polyhydroxy-substituted pyrido[2,3-d]pyrimidine derivatives. This new combinatorial approach gave a range of carbohydrate-derived heterocycles in good to excellent yields with high potential biological applications. The antioxidant activities were evaluated using 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) antioxidant measuring system, and the data were expressed as Trolox equivalent antioxidant capacity. All of these compounds display significant antioxidant activity. The maximum and minimum antioxidant activities were observed for 4j and 6b, respectively. Our results indicated encouraging perspectives for the improvement and usage of this type of synthetic compounds, indicating significant levels of antioxidant activity.
Project description:In the title compound, C(14)H(12)N(2)O(2), the dihedral angle between the phenyl ring and the 3,4-dimethyl-pyrano[2,3-c]pyrazol-6(1H)-one system is 7.28?(6)°. An intra-molecular C-H?O inter-action generates an S(6) ring. In the crystal, the mol-ecules are linked by C-H?O hydrogen bonds, forming C(8) chains. C-H?? and ?-? inter-actions [centroid-centroid separation = 3.6374?(12)?Å] further consolidate the packing.
Project description:The title compound, C(20)H(15)N(5)O(3), was synthesized by the one-pot reaction of a four-component reaction protocol in aqueous medium. The pyrano[2,3-c]pyrazole system is essentially planar, with a maximum deviation of 0.026?(2)?Å. The 3-nitro-phenyl and phenyl rings make dihedral angles of 81.11?(5) and 13.36?(1)°, respectively, with the mean plane of the pyrano[2,3-c]pyrazole ring. The crystal structure is stabilized by N-H?N hydrogen bonds, which form infinite chain propagating along the c axis and by N-H?O hydrogen bonds, which form infinite chains propagating along the a axis. There are also N-O?N-C dipole-dipole inter-actions along the a axis with an O?N distance of 3.061?(3)?Å, which is shorter than that of the N-H?O hydrogen bond [3.196?(3)?Å].
Project description:The Pd/C-CuI-PPh(3) catalytic system facilitated C-C bond formation between 4-chlorothieno[2,3-d]pyrimidines and terminal alkynes in methanol with high selectivity without generating any significant side products arising from C-O bond formation between the chloro compounds and methanol. A variety of novel 4-alkynylthieno[2,3- d]pyrimidines were prepared via alkynylation of 4-chlorothieno[2,3-d]pyrimidines in good to excellent yields. Some of the compounds synthesized were tested for cytotoxic activity in vitro.
Project description:In the title compound, C(15)H(9)Cl(2)F(3)N(2)O(2), the 1,6-dihydro-pyrano[2,3-c]pyrazole ring system is almost planar, with a maximum deviation of 0.0226?(14)?Å, and forms a dihedral angle of 69.90?(6)° with the benzene ring. In the crystal, mol-ecules are linked into a helical chain along the c axis by C-H?O hydrogen bonds.