Showing papers on "Benzopyran published in 2010"
TL;DR: An expeditious construction of a benzopyran skeleton via Lewis acid-catalyzed C-H functionalization was achieved, affording the desired compounds in excellent chemical yields with short reaction times.
119 citations
TL;DR: Various aliphatic aldehydes and substituted (E)-2-(2-nitrovinyl)phenols were proven to be well tolerated in this tandem reaction and could be conveniently transformed to synthetically and biologically significant chiral dihydrocoumarin, chroman, and 4H-chromene derivatives.
Abstract: Asymmetric tandem Michael addition−hemiacetalization between aliphatic aldehydes and (E)-2-(2-nitrovinyl)phenols was investigated for constructing benzopyran backbones. Interestingly, the diastereo- and enantioselectivities changed markedly when the reaction was mediated by different types of secondary amine catalysts. The diphenylprolinol silyl ether 7 promoted the reaction with excellent enantioselectivities (up to 99% ee) but with moderate diastereoselectivities (2.8:1 to 10:1). Prolylprolinols are another type of efficient catalyst. Among them, l,l-prolylprolinol 5c is identified as the optimal species, showing high catalytic activity, good enantioselectivities (up to 89% ee), and excellent diasereoselectivities (up to 50:1 dr). Various aliphatic aldehydes and substituted (E)-2-(2-nitrovinyl)phenols were proven to be well tolerated in this tandem reaction. In addition, the chroman-2-ols 3 yielded in the above reactions could be conveniently transformed to synthetically and biologically significant chi...
72 citations
TL;DR: In this article, a new series of eight derivatives of 4-pyrazolyl-4H-4P-P-O-Pyran and sixteen derivatives of naphthopyran has been synthesized by one-pot base-catalyzed cyclocondensation reactions of 1-phenyl-3-(het)aryl- pyrazole-4-carbaldehyde, malononitrile and substituted pyrazolin-5-ones or dimedone or naphthsols respectively.
Abstract: A new series of eight derivatives each of 4-pyrazolyl-4H-pyrazolopyran, -benzopyran and sixteen derivatives of naphthopyran has been synthesized by one-pot base-catalyzed cyclocondensation reactions of 1-phenyl-3-(het)aryl-pyrazole-4-carbaldehyde, malononitrile and substituted pyrazolin-5-ones or dimedone or naphthols respectively. All the synthesized compounds were subjected to in vitro antimicrobial screening against a panel of pathogenic strains of bacteria and fungi. Some of the compounds were found to be equipotent or more potent than commercial antibiotics against most of employed strains.
35 citations
TL;DR: Novel chloromethylated and hydroxymethylated 2-oxo-2H-benzo[h]benzopyran derivatives bearing a methoxy substituent were designed and used in the synthesis of a series of fluorescent bioconjugates by linking through an ester or urethane bond to several model neurotransmitter amino acids.
Abstract: Aiming at the development of new benzopyran-based photocleavable protecting groups, novel chloromethylated and hydroxymethylated 2-oxo-2H-benzo[h]benzopyran derivatives bearing a methoxy substituent were designed and used in the synthesis of a series of fluorescent bioconjugates, by linking through an ester or urethane bond to several model neurotransmitter amino acids (glycine, alanine, β-alanine and γ-aminobutyric acid, GABA). The resulting fluorescent bioconjugates with emission in the visible range and high fluorescent quantum yields, were subjected to photocleavage reaction in methanol/HEPES buffer (80:20) solution at different wavelengths of irradiation (250, 300, 350 and 419 nm) and photocleavage kinetic data were obtained.
29 citations
TL;DR: In this paper, the synthesis of pentacyclic benzopyran-annulated thiopyrano[2,3-b ] thiochromen-5(4 H )-ones has been described.
28 citations
TL;DR: The linear 9-methoxy-2,2-dimethyl-2H-benzofuro[2,3-g][1]benzopyran exhibiting a good antimycobacterial activity and devoid of cytotoxicity appeared to be the most promising compound.
27 citations
TL;DR: In this article, a benzopyran entity annulated with a 15crown-5 ether unit and three metal cations, Mg 2+, Ba 2+ and Pb 2+ has been investigated by UV-vis and NMR spectroscopy.
Abstract: Complexation between a benzopyran entity annulated with a 15-crown-5 ether unit and three metal cations, Mg 2+ , Ba 2+ , and Pb 2+ has been investigated by UV–vis and NMR spectroscopy. The complexes composition, the stability constants and the structural arrangements have been determined. The photochemical and thermal properties of the photochromic benzopyran derivative in absence and in the presence of metals have been studied. The metal-ion-binding ability of the fused macrocyclic entity drastically modifies photochromism by decreasing the thermal stability of photomerocyanines, whereas the metal cations are partially ejected from crown-ether cavity when benzopyran is in open configuration.
26 citations
23 citations
TL;DR: A key role of Phe544 is demonstrated in the binding of the benzopyran IRAP inhibitors and for optimal positioning of enzyme substrates during catalysis.
Abstract: Inhibitors of insulin-regulated aminopeptidase (IRAP) improve memory and are being developed as a novel treatment for memory loss. In this study, the binding of a class of these inhibitors to human IRAP was investigated using molecular docking and site-directed mutagenesis. Four benzopyran-based IRAP inhibitors with different affinities were docked into a homology model of the catalytic site of IRAP. Two 4-pyridinyl derivatives orient with the benzopyran oxygen interacting with the Zn2+ ion and a direct parallel ring-stack interaction between the benzopyran rings and Phe544. In contrast, the two 4-quinolinyl derivatives orient in a different manner, interacting with the Zn2+ ion via the quinoline nitrogen, and Phe544 contributes an edge-face hydrophobic stacking point with the benzopyran moiety. Mutagenic replacement of Phe544 with alanine, isoleucine, or valine resulted in either complete loss of catalytic activity or altered hydrolysis velocity that was substrate-dependent. Phe544 is also important for inhibitor binding, because these mutations altered the Ki in some cases, and docking of the inhibitors into the corresponding Phe544 mutant models revealed how the interaction might be disturbed. These findings demonstrate a key role of Phe544 in the binding of the benzopyran IRAP inhibitors and for optimal positioning of enzyme substrates during catalysis.
21 citations
TL;DR: The synthesis of novel fused-ring bicyclic and tricyclic nicotine derivatives from natural (S)-nicotine are described and attempts to synthesize furonicotines resulted in formation of the furonicotine dimers 42 and 49.
Abstract: The synthesis of novel fused-ring bicyclic (4-6) and tricyclic (7-10) nicotine derivatives from natural (S)-nicotine are described. Enantiopure bicyclic dioxino, dihydrofuro, and dihydropyranol nicotine derivatives as well as tricylic benzofuro and benzopyran derivatives were synthesized from simple alkoxy or halonicotine intermediates. Attempts to synthesize furonicotines (11, 12) resulted in formation of the furonicotine dimers 42 and 49.
19 citations
TL;DR: InCl3 catalyzed reactions of 2-C-acetoxymethylglycal derivatives with different phenolic compounds resulted in the formation of sugar-based pyrano-arenopyrans in good yields and moderate to excellent diastereoselectivity as discussed by the authors.
TL;DR: In this paper, the photocatalytic transformation of HHCB (1,3,4,6,7,8-hexahydro-4, 6,6.7, 8,8, 8-hexamethylcyclopenta[γ]-2-benzopyran, trade name Galaxolide), under simulated solar irradiation using titanium dioxide as a photocatalyst, was investigated.
Abstract: The present paper deals with the photocatalytic transformation of HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran, trade name Galaxolide), under simulated solar irradiation using titanium dioxide as a photocatalyst. The investigation has involved a study of HHCB decomposition under a variety of experimental conditions, the identification of intermediate compounds, as well as the assessment of mineralization. A fully nested experimental design was applied to study the effect of various matrices (i.e. distilled water, surface water and wastewater) as well as the initial HHCB concentration on the variation of the photocatalytic efficiency. GC/MS and LC/MS were brought to bear in assessing the temporal course of the photocatalyzed process. A first pathway involves the hydroxylation, that is confined to the benzopyran moiety. Another route proceeds through the detachment of the hexamethylpentacycle moiety, with the formation of the ketoderivative. A parallel transformation involves benzopyran moiety with the ring cleavage. All the identified transformation products are degraded themselves until 2 h of irradiation, while complete mineralization is achieved until 8 h.
TL;DR: During a synthesis of coumarins to obtain new candidates for treating Alzheimer’s Disease (AD), an unusual rearrangement of a benzopyran group to a benzofuran group occurred, offering a novel synthesis pathway of these benz ofuran derivatives.
Abstract: During a synthesis of coumarins to obtain new candidates for treating Alzheimer’s Disease (AD), an unusual rearrangement of a benzopyran group to a benzofuran group occurred, offering a novel synthesis pathway of these benzofuran derivatives. The possible mechanism of the novel rearrangement was also discussed. All of the benzofuran derivatives have weak anti-AChE activities compared with the reference compound, donepezil.
TL;DR: In this article, a single-step reaction of 4-hydroxydithiocoumarin with O-allylated salicylaldehyde and O-propargylated Salicyl-aldehyde in aqueous medium is described.
Abstract: Benzopyran-annulated thiopyrano[2,3-b]thiochromen-5(4H)-ones have been synthesized by the domino Knoevenagel-hetero-Diels-Alder (DKHDA) reaction of 4-hydroxydithiocoumarin with O-allylated salicylaldehyde and O-propargylated salicyl-aldehyde in aqueous medium. The reaction requires only a single step operation and is highly regio- and stereoselective providing potentially bioactive polycyclic heterocycles in high yields.
TL;DR: A mild and efficient protocol for the synthesis of the benzopyran ring has been described and a series of chromans compounds are reported, the yield is from 72% to 95% as mentioned in this paper.
Abstract: A mild and efficient protocol for the synthesis of the benzopyran ring has been described and a series of chromans compounds is reported, the yield is from 72% to 95%. The diadduct tended to angular product and showed good regioselectivity. This strategy was applied for the benzopyran derived natural products (±)-xyloketals and (±)-alboatrin. The crystal of compound 9 exhibited centro-symmetric space group, containing two isomers in one unit. The relative configurations were 1R,10R,15S and 34S,22R,30S, respectively.
TL;DR: In this article, 2-(Alkyl/arylamino)chromone-3-carbaldehyde reacts with Meldrum's acid, hippuric acid, 4-hydroxycoumarin, diethyl malonate, ethyl acetoacetate, or ethyl benzoylacetate to produce 1-benzopyrano[2,3-b]pyridine-2,5-dione moiety.
TL;DR: In this paper, the synthesis of 4H-benzopyran derivatives using dialdehyde as a key starting material was investigated using microwave irradiation in good yield (87%-95%) with short reaction time (5-8 min).
Abstract: The syntheses of 4H-benzopyran derivatives were investigated using dialdehyde as a key starting material. The reaction proceeds under microwave irradiation in good yield (87%-95%) with short reaction time (5-8 min), therefore providing a rapid and efficient method of synthesizing a variety of compounds containing two 4H-benzopyran units.
TL;DR: In this paper, the conformation of the dihydropyran ring and the chemical shift differences in the pairs of isomeric adducts are discussed, as well as the properties of these products and related compounds.
Abstract: Reaction of 1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indolines] with 1,1-bis[4-(dimethylamino)phenyl]ethylene can give two types of isomeric products, 2,2-bis[4-(dimethylamino)-phenyl]-4-{2-methylidene-1,3,3-trimethylindoline}chromans (2a–e) and 1′,3′,3′-trimethyl-4-{2,2-bis[4-(dimethylamino)phenyl]vinyl}-spiro[chroman-2,2′-indolines] (3a–d).
These products and related compounds have been analysed by spectroscopic methods. The conformation of the dihydropyran ring and the chemical shift differences in the pairs of isomeric adducts are discussed.
TL;DR: A new series of 3,4‐dihydro‐3‐amino‐2H‐1‐benzopyran derivatives bearing various substituents on the 5‐position was successfully prepared via palladium‐mediated cross‐coupling reactions and some of the new compounds showed high affinity for 5‐HT1A and5‐HT7 receptors.
Abstract: A new series of 3,4-dihydro-3-amino-2H-1-benzopyran derivatives (1 and 2) bearing various substituents on the 5-position was successfully prepared via palladium-mediated cross-coupling reactions. Some of the new compounds showed high affinity for 5-HT1A and 5-HT7 receptors. The best affinity for the 5-HT1A and 5-HT7 receptors was obtained for 2b (Ki = 0.3 nM for 5-HT1A and 3.1 nM for 5-HT7). The anxiolytic activity of compound 2b was evaluated.
TL;DR: The molecule of O-acetylswietenolide, C29H36O9, isolated from the seeds of Swietenia macrophylla, features four six-membered rings connected together in the shape of a bowl; one of the inner rings adopts a twisted chair conformation owing to the C=C double bond.
Abstract: The molecule of O-acetylswietenolide, C29H36O9, isolated from the seeds of Swietenia macrophylla, features four six-membered rings connected together in the shape of a bowl; one of the inner rings adopts a twisted chair conformation owing to the C=C double bond The furyl substitutent is connected to an outer ring, and it points away from the bowl cavity The hydroxy group is connected to a carbonyl O atom of an adjacent molecule by an O—H⋯O hydrogen bond, generating a chain running along the b axis
TL;DR: A series of novel six-membered tetracyclic compounds, the title benzopyranoquinolines, was synthesized by reaction of 2-amino-3-cyanobenzopyrans (I) with 5-substituted 1,3-cyclohexanedione derivatives.
TL;DR: In this paper, the synthesis of new flavonoid derivatives, which possess a 1,4-dihydropyridine (1, 4-DHP) moiety on the phenyl ring of flavone were realized.
Abstract: In this study, the synthesis of new flavonoid derivatives, which possess a 1,4-dihydropyridine (1,4-DHP) moiety on the phenyl ring of flavone were realized. 3' or 4'-Formyl-flavones were synthesized, then the aldehyde groups of these compounds were converted to the 1,4-DHP moiety by the Hantzsch method. A series of 23 new derivatives having different substituents at C-3 and C-5 of the 1,4-DHP ring were prepared. Two compounds (8a, 8b) were tested for their calcium channel blocker activity and 8b exhibited the best result.
TL;DR: The title compound, C18H16O7·H2O, is a flavonoid isolated from Dodonaea viscosa that is involved in extensive hydrogen bonding, assembling the molecules into a supramolecular network via classical intermolecular O—H⋯O hydrogen bonding.
Abstract: The title compound, C18H16O7·H2O, is a flavonoid isolated from Dodonaea viscosa. The benzopyran ring system of the flavonoid is essentially planar [maximum deviation = 0.025 (2) A] and inclined at 5.83 (2)° to the attached benzene ring. The water of hydration is involved in extensive hydrogen bonding, assembling the molecules into a supramolecular network via classical intermolecular O—H⋯O hydrogen bonding. The crystal structure is further stabilized by π–π stacking interactions [centroid–centroid distance between benzene rings = 3.564 (3) A].
TL;DR: A new benzopyran derivative, malloapeltic acid (1), along with seven known compounds, was isolated from the roots of Mallotus apelta.
Abstract: A new benzopyran derivative, malloapeltic acid (1), along with seven known compounds, was isolated from the roots of Mallotus apelta. The structure of the new compound 1 was elucidated by spectroscopic data analysis. The known compounds 2–8 were identified by comparison of their spectroscopic data with reported values in the literature. Compound 1 showed strong anti-HIV activity in vitro.
TL;DR: In this paper, the in vitro activities of the obtained euryfurylquinones and hydroquinones against Leishmania amazonensis were described, and one of these Michael adducts undergoes a facile stereoselective cyclisation under oxidant conditions to afford a naphthofuro[4,3-c]benzopyran derivative.
Abstract: (+)-Euryfuran adds regiospecifically to activated monosubstituted 1,4-benzoquinones under mild conditions to give the corresponding Michael adducts which, depending on the quinone substituent, undergo in situ redox reactions to the respective euryfurylbenzoquinones. One of these Michael adducts undergoes a facile stereoselective cyclisation under oxidant conditions to afford a naphthofuro[4,3-c]benzopyran derivative. The in vitro activities of the obtained euryfurylquinones and hydroquinones against Leishmania amazonensis are described.
TL;DR: In this article, the conformation of 7-decanoyloxy-3-(4′-methylphenyl)-4H-1-benzopyran-4-one was determined by single crystal X-ray diffraction analysis of which the title compound crystallized into triclinic lattice with P-1 space group.
TL;DR: In this article, the authors add 9,10-phenanthrenequinone or 3,5-di-tert-butyl-o-benzoquinone to N,N-dialkyl-3-alken-1-ynyl-1amines R2-CHCH-C≡C-NR12 (4) gives quinoid α-ALKENyl-γ-oxo-α,β-unsaturated carboxamides 6 or 8, respectively; these undergo a spontaneous ring-closure, or can be cycl
Abstract: Addition of 9,10-phenanthrenequinone or 3,5-di-tert-butyl-o-benzoquinone to N,N-dialkyl-3-alken-1-ynyl-1-amines R2-CHCH-C≡C-NR12 (4) gives quinoid α-alkenyl-γ-oxo-α,β-unsaturated carboxamides 6 or 8, respectively; these undergo a spontaneous ring-closure, or can be cyclised photochemically into 2H-phenanthro[9,10-b]pyran-4-carboxamides 7 or 2H-1-benzopyran-4-carboxamides 9.
TL;DR: In this article, an efficient and improved procedure for the synthesis of benzopyran derivatives has been achieved with Keggin-type and Preyssler-type HPA catalysts in one-pot reaction under solvent-free conditions.
Abstract: An efficient and improved procedure for the synthesis of benzopyran derivatives has been achieved with Keggin-type and Preyssler-type heteropolyacids (HPA) catalysts in one-pot reaction under solvent-free conditions.
TL;DR: In this article, 3-Iodo-4-chalcogen-2 H -benzopyran derivatives underwent a direct Sonogashira cross-coupling reaction with several terminal alkynes in the presence of a catalytic amount of Pd(PPh 3 ) 2 Cl 2 with CuI as a co-catalyst, using Et 3 N as base and solvent.