Pyranone Moiety Research Articles

An Overview of the Synthesis of 3,4-Fused Pyrrolocoumarins of Biological Interest.

3,4-Fused pyrrolocoumarins, synthetically prepared or naturally occurring, possess interesting biological properties. In this review, the synthetic strategies for the synthesis of the title compounds are presented along with their biological activities. Two routes are followed for that synthesis. In one, the pyrrole ring is formed from coumarin derivatives, such as aminocoumarins or other coumarins. In the other approach, the pyranone moiety is built from an existing pyrrole derivative or through the simultaneous formation of coumarin and pyrrole frameworks. The above syntheses are achieved via 1,3-dipolar cycloaddition reactions, Michael reaction, aza-Claisen rearrangement reactions, multi-component reactions (MCR), as well as metal-catalyzed reactions. Pyrrolocoumarins present cytotoxic, antifungal, antibacterial, α-glucosidase inhibition, antioxidant, lipoxygenase (LOX) inhibition, and fluorescent activities, as well as benzodiazepine receptor ability.

An Overview on the Synthesis of Fused Pyridocoumarins with Biological Interest.

Pyridocoumarins are a class of synthetic and naturally occurring organic compounds with interesting biological activities. This review focuses on the synthetic strategies for the synthesis of pyridocoumarins and presents the biological properties of those compounds. The synthesis involves the formation of the pyridine ring, at first, from a coumarin derivative, such as aminocoumarins, hydroxycoumarins, or other coumarins. The formation of a pyranone moiety follows from an existing pyridine or piperidine or phenol derivative. For the above syntheses, [4 + 2] cycloaddition reactions, multi-component reactions (MCR), as well as metal-catalyzed reactions, are useful. Pyridocoumarins present anti-cancer, anti-HIV, antimalarial, analgesic, antidiabetic, antibacterial, antifungal, anti-inflammatory, and antioxidant activities.

Synthesis of Open‐Cage Fullerenes with Pyrrole, Pyrrolone, Pyridinone, Iminofuran, and Pyranone Fragments Embedded on the Rim of the Orifice

AbstractAn open‐cage fullerene derivative with a pyranone and a diiminopentanone moiety was prepared. Further reaction with aniline could convert the pyranone moiety into a pyrrole moiety through the pyridinone moiety as an intermediate. During the process, decarboxylation and dehydroxylation aromatization reactions also took place on the diiminopentanone moiety and the two adjacent hydroxyl groups, thus forming iminofuran or pyrrolone moiety on the rim of the open‐cage fullerene. Protonation experiment showed that the imino nitrogen atom on the rim of the orifice is more basic than the pyrrole nitrogen atom. The lone pair of the pyrrole nitrogen is partially conjugated with the π system of the fullerene cage as shown by single crystal X‐ray structures.

New possibilities of 2-pyranone derivatives – Thermal, optical and electrochemical properties

The paper contains a comprehensive study regarding the new possibilities of using 2-pyranone derivatives. In this work, six compounds of this type (including three electropolymerisable bithiophenyl's monomers) were synthesized in a one-step reaction with high yields ranging from 57% to 81%. The synthesized monomers of Bt-py-Bt (where Bt = 2,2′-bithiophene-5-yl, py = pyranone moiety) type were transformed into conducting polymers in an electrochemical oxidation process. The influence of the pyranone bridge on the stability, luminescent and (spectro)electrochemical behaviour was thoroughly studied. The polymers present extraordinary stability during both multiple n- and p-doping. The experimental results were also investigated theoretically, using the DFT approach. Calculations of the frontier orbital energies and the corresponding Eg value were done for each polymer using periodic boundary conditions. Finally, the electrochemical impedance spectroscopy measurements of polymeric films were done and evaluated.

Conosiligins A-D, Ring-Rearranged Tremulane Sesquiterpenoids from Conocybe siliginea.

Conosiligins A-D (1-4), four ring-rearranged sesquiterpenoids, were isolated from cultures of the basidiomycete Conocybe siliginea. Their structures and absolute configurations were determined by detailed spectroscopic analyses and equivalent circulating density (ECD) calculations. Compounds 1 and 2 possess a 5/8-fused ring system, while 3 has a 5/6-fused backbone conjugated with a γ-lactone. Compound 4 is a 5,6-seco tremulane derivative with the loss of a skeletal carbon, featuring a tetracyclic system involving a pyranone moiety. Compounds 3 and 4 inhibited Con A-induced T cell proliferation with IC50 values of 12.3 and 6.6 μM, respectively.

An Overview on Pyranocoumarins: Synthesis and Biological Activities

Pyrano- and dipyranocoumarins are classes of naturally occurring organic compounds with very interesting biological activities. This review focuses on the synthetic strategies for the synthesis of pyranocoumarins and dipyranocoumarins and the biological properties of those compounds. The synthesis involves the formation of the pyran ring, at first, from a coumarin or the formation of pyranone moiety from an existing pyran. Pyranocoumarins and dipyranocoumarins present anti-HIV, anti-cancer, neuroprotective, antidiabetic, antibacterial, antifungal, anti-inflammatory activities. Especially khellactones and calanolides are usually potent and selective in anti-HIV activity. Decursin and decursinol derivatives are effective as anticancer, neuroprotective, antidiabetic, antibacterial, and antifungal agents.

Construction and functionalization of pyranone ring fused with pyran moiety: Design and synthesis of novel pyrano[4,3-b]pyran-5(4H)-ones as potential inhibitors of sirtuins

Novel pyrano[4,3-b]pyran-5(4H)-one based small molecules were designed as potential inhibitors of sirtuins (i.e., yeast sir2, a homolog of human SIRT1). Elegant synthesis of these compounds was performed via a multi-step sequence consisting of MCR, Sandmeyer type iodination, Sonogashira type coupling followed by iodocyclization and then Pd-mediated various C–C bond forming reactions. The overall strategy involved the construction of a pyran ring followed by the fused pyranone moiety and subsequent functionalization at C-8 position of the resultant core pyrano[4,3-b]pyran-5(4H)-one framework. The crystal structure analysis of a representative iodolactonized product (6d) is presented. Some of the synthesized compounds showed promising inhibitory activities when tested against yeast sir2 in vitro. The compound 6g showed dose dependent inhibition (IC50=78.05μM) of yeast sir2 and good interactions with this protein in silico.

Thieno[3,2-c]pyran-4-one based novel small molecules: Their synthesis, crystal structure analysis and in vitro evaluation as potential anticancer agents

Novel thieno[3,2-c]pyran-4-one based small molecules were designed as potential anticancer agents. Expeditious synthesis of these compounds was carried out via a multi-step sequence consisting of few steps such as Gewald reaction, Sandmeyer type iodination, Sonogashira type coupling followed by iodocyclization and then Pd-mediated various C–C bond forming reactions. The overall strategy involved the construction of thiophene ring followed by the fused pyranone moiety and then functionalization at C-7 position of the resultant thieno[3,2-c]pyran-4-one framework. Some of the compounds synthesized showed selective growth inhibition of cancer cells in vitro among which two compounds for example, 5d and 6c showed IC50 values in the range of 2.0–2.5μM. The crystal structure analysis of an active compound along with hydrogen bonding patterns and molecular arrangement present within the molecule is described.

ChemInform Abstract: Stereoselective Synthesis of β‐Amino Ketones Possessing β‐[(2H‐Pyran‐2‐one)‐3‐yl]‐β‐chlorovinyl Moiety via Three‐Component Direct Mannich Reaction, Catalyzed with ZrOCl2·8H2O.

AbstractThe new β‐chloroacrolein with a pyranone moiety (III) is subjected to a three‐component Mannich‐type reaction with anilines (IV), cyclic ketones (V), and acyclic ketones in the presence of a zirconium catalyst.

Cyclization vs. Elimination Reactions of 5‐Aryl‐5‐hydroxy 1,3‐Diones: One‐Pot Synthesis of 2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones

Abstract2‐Aryl‐2,3‐dihydro‐4H‐pyran‐4‐ones were prepared in one step by cyclocondensation of 1,3‐diketone dianions with aldehydes. The use of HCl (10%) for the aqueous workup proved to be very important to avoid elimination reactions of the 5‐aryl‐5‐hydroxy 1,3‐diones formed as intermediates. The TiCl4‐mediated cyclization of a 2‐aryl‐2,3‐dihydro‐4H‐pyran‐4‐one with 1,3‐silyloxybuta‐1,3‐diene resulted in cleavage of the pyranone moiety and formation of a highly functionalized benzene derivative.

Fully and partially fluorinated flavone derivatives

In the crystal structures of the fully and partially fluorinated flavone derivatives 5,6,7,8-tetrafluoro-2-(2,3,4,5,6-pentafluorophenyl)-4H-1-benzopyran-4-one, C(15)HF(9)O(2), (I), and 5,6,7,8-tetrafluoro-2-phenyl-4H-1-benzopyran-4-one, C(15)H(6)F(4)O(2), (II), the pentafluorophenyl group and the pyranone moiety in (I) are twisted due to repulsion of the F substituents, and a CO(delta(-))...pi(delta(+)) intermolecular interaction is observed between the carbonyl O atom and the pentafluorophenyl group. In (II), on the other hand, the phenyl group and the pyranone moiety are almost coplanar, and arene-perfluoroarene interactions are observed in the head-to-tail intermolecular columnar stacking between the phenyl group and the tetrafluorophenylene moiety.

Stereoselective Synthesis of (−)-Spicigerolide

(-)-Spicigerolide was stereoselectively synthesized from a protected (S)-lactaldehyde. The synthesis of the polyacetylated framework relied on two Zn-mediated stereoselective additions of alkynes to aldehydes as well as a regiocontrolled [3,3]-sigmatropic rearrangement of an allylic acetate. The pyranone moiety was constructed via ring-closing metathesis.

Synthesis and nonlinear optical properties of linear and Λ-shaped pyranone-based chromophores

New, pyranone-based chromophores were synthesized and their (nonlinear) optical properties were measured. The chromophores were prepared by first condensing an electron withdrawing group with pyranone, followed by reaction with an aldehyde-functionalized π-conjugated bridged donor molecule. This approach enables one to easily incorporate the pyranone moiety and to prepare both linear and Λ-shaped chromophores. The (nonlinear) optical properties were measured using femtosecond hyper-Rayleigh scattering. These measurements demonstrated the advantages of this approach.

Spectral properties and conformations of nonlinear ketocyanines

The electronic transitions in molecules of the ketocyanine dyes (polyenic ω,ω′-bisamino ketones) were calculated by quantum chemical methods. Satisfactory agreement was obtained between the experimental bands of the S-S absorption spectra and calculated electronic transitions for the ketocyanine with the central pyranone moiety and the corresponding salt assuming an acute angle between the chromophores and for the ketocyanine with the central pyridone moiety assuming an obtuse angle between the chromophores. Such molecular conformations were confirmed by the gNOESY 1H NMR data for these dyes. The difference in the conformations of the dyes with the pyranone and pyridone moieties is due, most likely, to steric hindrance created by the central methyl groups in the molecules of the latter. The salts corresponding to these dyes have similar conformational differences.

TD-DFT Investigation of the UV Spectra of Pyranone Derivatives

The UV absorption spectra of more than 80 substituted coumarins and chromones have been investigated with the PCM-TD-DFT theoretical scheme using three hybrid functionals (O3LYP, B3LYP, and PBE0) and taking into account methanol or ethanol solvation effects. For most of the studied derivatives, there are at least two allowed excited states presenting a strong oscillator strength in the UV region. The first allowed excitation is associated to a HOMO-LUMO transition whereas the second corresponds to a transition from the HOMO-1 to the LUMO. Both involve a charge transfer from the benzenic cycle to the pyranone moiety. Statistically treating the PBE0 results allows a prediction of the lambda(max) with small standard deviations: in methanol, 6 nm (0.07 eV) for the first excitation (lambda(max)(1)) and 5 nm (0.08 eV) for the second one (lambda(max)(2)), whereas in ethanol 6 nm (0.08 eV) for (lambda(max)(1)) and 6 nm (0.13 eV) for (lambda(max)(2)).

Studies on steroidal plant growth regulator 27. Stereoselective construction of the side chain of brassinosteroid by employing a separated dialkylation and a tandem dialkylation of the pyranone moiety

AbstractA stereocontrolled construction of the Bide chain of brassinosteroid was developed via the separated dialkylation and the tandem dialkylation of the pyranone moiety as the key step.

Stereocontrolled synthesis of the brassinolide side chain via a pyranone derivative

A new method for assembling the brassinolide side chain from 20-carboxaldehyde 2 was developed via the stereoselective construction of the pyranone moiety as key steps.