4,5,6-三取代-2H-吡喃-2-酮的简便合成法

2H-吡喃-2-酮及其衍生物是有机合成的蓬要中间体。对于它们的合成已有许多报道,例如利用烯醇醚或烯醇砖醚与丁酰氯反应;羰基化合物与甲氧亚甲螭丙二酸二甲酯反应;α-苯基丙醛酸酯与丙酮的成环缩合2,6-二氯-3-三氯甲基吡啶与亚甲基丁二酸酯的反应,邻氰基苯乙炔、二苯乙二酮和丙酮的反应。但上述方法往往原料较难得到,产率较低或操作麻烦。     

Enzymatic formation of an unnatural methylated triketide by plant type III polyketide synthases

Octaketide synthase, a novel plant-specific type III polyketide synthase from Aloe arborescens, efficiently accepted (2RS)-methylmalonyl-CoA as a sole substrate to produce 6-ethyl-4-hydroxy-3,5-dimethyl-2-pyrone. On the other hand, a tetraketide-producing chalcone synthase from Scutellaria baicalensis and a diketide-producing benzalacetone synthase from Rheum palmatum also yielded the unnatural methylated C₉ triketide pyrone as a single product by sequential decarboxylative condensations of three molecules of (2RS)-methylmalonyl-CoA.     

Polymorphism in 3‐acetyl‐4‐hydroxy‐2H‐chromen‐2‐one

A new polymorph (denoted polymorph II) of 3‐acetyl‐4‐hydroxy‐2H‐chromen‐2‐one, C₁₁H₈O₄, was obtained unexpectedly during an attempt to recrystallize the compound from salt–melted ice, and the structure is compared with that of the original polymorph (denoted polymorph I) [Lyssenko & Antipin (2001). Russ. Chem. Bull. 50 , 418–431]. Strong intramolecular O—H...O hydrogen bonds are observed equally in the two polymorphs [O...O = 2.4263 (13) Å in polymorph II and 2.442 (1) Å in polymorph I], with a slight delocalization of the hydroxy H atom towards the ketonic O atom in polymorph II [H...O = 1.32 (2) Å in polymorph II and 1.45 (3) Å in polymorph I]. In both crystal structures, the packing of the molecules is dominated and stabilized by weak intermolecular C—H...O hydrogen bonds. Additional π–π stacking interactions between the keto–enol hydrogen‐bonded rings stabilize polymorph I [the centres are separated by 3.28 (1) Å], while polymorph II is stabilized by interactions between α‐pyrone rings, which are parallel to one another and separated by 3.670 (5) Å.     

应用量化参数和拓扑指数研究吡喃酮类化合物结构与活性的相关性

QSAR;量子化学参数;应用量化参数和拓扑指数研究吡喃酮类化合物结构与活性的相关性     

Synthesis and characterization of new soluble polyamides derived from 2,6-bis(4-aminophenyl)-3,5-dimethyltetrahydro-4H-pyran-4-one

A new oxypyrone diamine, 2,6-bis(4-aminophenyl)-3,5-dimethyltetrahydro-4H-pyran-4-one (DAPP), was prepared from 4-nitrobenzaldehyde and 3-oxa-n-pentane in a two-step reaction with a high yield and a high purity. Aromatic polyamides were obtained from this novel condensation monomer and several diacid chlorides through the conventional low-temperature solution method in N,N-dimethylacetamide. Polycondensation results were consistent with a high reactivity for DAPP because high yields and high molecular weight polyamides were obtained with inherent viscosities up to 1.8 dL/g. The reactivity of DAPP was also estimated with theoretical calculations from computer programs for molecular simulation, with orbital and charge factors considered. The polymers showed improved solubility in organic solvents, relative to conventional wholly aromatic polyamides, and high glass-transition temperatures (from differential scanning calorimetry) over 270 °C. However, the thermal resistance, as estimated by thermogravimetric analysis, was lower than that of conventional aromatic polyamides; nevertheless, decomposition temperatures well beyond 300 °C were observed in nitrogen and air. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1825–1832, 2001     

多甲基α-吡喃酮的简捷合成方法

以α-甲基丙酰乙酸乙酯为原料,经动力学去质子化后,与乙酸乙酯发生γ-酰基化反应,然后环合生成3,5,6-三甲基-4-羟基-2-吡喃酮,在回流丁酮中甲基化主要得到3,5,6-三甲基-4-甲氧基-2-吡喃酮。两步反应总收率15．2％,经IR,^1H—NMR,MS分析确定了目标化合物的分子结构。     

Antioxidant potential of styrene pyrone polyphenols from Inonotus obliquus: A combined experimental,density functional theory (DFT) approach and molecular dynamic (MD) simulation

Polyphenols containing styrene pyranone skeleton are unique to porous fungi. Inonotus obliquus (IO) is a medicinal and edible porous fungus. Twelve phenolic compounds containing four styryl pyranone polyphenols from IO were isolated and identified in this work. The antioxidant ability of the isolates was characterized utilizing the ferric reducing antioxidant power (FRAP) assay and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging test. Styrylpyranone polyphenols, especially methylinoscavin B, could capture free radicals better than other phenolic compounds, and quantum chemical calculations also confirmed this evaluation. The density functional theory (DFT) calculation data showed that Styrylpyranone polyphenols, especially methylinoscavin B, have a lower energy gap, higher softness and higher electronic chemical potential than other phenolic compounds. The bond dissociation energy values of the bond in C7ʹ O–H of the methylinoscavin B molecule are less than those in C11 and C6ʹ O–H when reacting with ∙OOH (selected as a representative free radical). On the basis of calculations, hydrogen atom transfer (HAT) is supposed to be a preferred mechanism over single electron transfer (SET) when phenolic compounds react with free radicals. Moreover, after treatment with final concentrations of 0.5, 1, 2, 3, 4 and 5 μM phelligridin E (PHE), the activity of SOD1 increased by 70.15%, 11.36%, 145.45%, 172.73%, 205.05% and 275.23%, respectively. The molecular dynamics simulation (MD) study of PHE employed SOD1 (PDB ID: 6FN8). The MD results showed that the hydrogen bonds between ASP147 of SOD1 and PHE promote GLU223-ARG224 to form a stable C coil after combining with PHE. The formation of the C Coil enhanced the stability of the electrostatic loop (EL) of SOD1 and the rate of diffusion of the superoxide anion to the active site. Styrylpyrone polyphenols of Inonotus obliquus origin have the potential to be a source of vigorous free radical scavengers and antioxidant enzyme activators.     

Solid‐State Regioselective Cyclization Initiated by the Electrophilic Attack on the Double Bond by N‐Bromosuccinimide on Montmorillonite K‐10 Clay Support under Microwave Irradiation

3‐Allyl‐4‐hydroxy‐coumarins and pyrones were regioselectively cyclized with N‐bromosuccinimide (NBS) on solid phase under microwave irradiation in excellent yield. NBS on montmorillonite K‐10 clay under microwave irradiation for expeditious solvent‐free regioselective cyclization has been used for the first time.     

Study towards bioactive pyrone derivatives from the marine red alga Phacelocarpus labillardieri

Red algae of the genus Phacelocarpus labillardieri produce a structurally rather unique class of macrocyclic pyrone derivatives with phospholipase A₂ inhibiting properties and potential neuromuscular blocking activity. They were also shown to be potent feeding inhibitors for various marine herbivorous gastropods. Described herein is the first preparative study towards these conspicuous secondary metabolites. Their carbon skeleton has been assembled in a few straightforward steps using ring closing alkyne metathesis (RCAM) catalyzed by the Schrock alkylidyne complex (tBuO)₃WCCMe₃ to forge the meta-cyclophane core with high efficiency.