4-Pyrones compounds

Qian FG, Xu GY, Du SJ, Li MH (1990) Isolation and Identification of Two New Pyrone Compounds from the Culture of Hericium erinaceus. Acta Pharm Sinica 25 522... 

The reaction of oxovinylidenetriphenylphosphorane or its dimer with aromatic carboxylic acid chlorides leads not to cyclobutanedione derivatives but to pyrone compounds, which can be converted to open chained bisphosphoranes with sodium methoxide (equation 104). If the acid chlorides carry an... 

Kretzschmar R, Meyer HJ, Teschendorf HJ. Strychnine antagonistic potency of pyrone compounds of the kavaroot (Piper methysticum Forst). Experientia 1970 26 283-284. 

The problem was later clarified with the finding that methylation of styryl-6-dihydropyran-2,4-dione, an analogue of yangonolactone, by diazomethane yielded a mixture of isomeric CC-pyrone and y-pyrone compounds as shown in Figure 5.4. These compounds were separated on the basis of the difference in solubilities of their hydrochloride oxonium salts in ether. The compound which formed an ether insoluble salt... 

Other examples of C-1 substituted glycals are compounds (1) and (2) which have been obtained, respectively, by eliminations from tri-O-benzoyl-L-rhamno-pyranosyl nitrile and 2,3 4,5-di-0-benzylidene-L-sorbofuranose. The former product, on debenzoylation, gave a diol which could be oxidized to the conjugated enone or the 7-pyrone compound (2) was derived by use of butyl-lithium. ... 

Parent CO-RM 8 was the first pyrone compound to be tested in a myoglobin assay and it was unfortunately discovered that it did not release-CO in a myoglobin assay. This shows that this particular CO-RM is stable in aqueous solution and in the presence of myoglobin. It was not tested for co-release using irradiation but it is certainly possible that it could. 

Ichimoto, L Ueda, H. Tatsumi C. (1965) Studies on kojic acid and its related y-Pyrone compounds. Part VII. The alkylation of Kojic Acid and Pyromeconic Acid through their Mannich Base. Agric. Biol Chem., Vol.l(2), pp.94-98. 

It may be regarded as the parent of a number of important classes of compounds derived from the y-pyrone skeleton (e.g. flavone, xan-thone) and the important chroman derivatives called the tocopherols (vitamin E). 

Pharmacological Profiles of Anxiolytics and Sedative—Hypnotics. Historically, chemotherapy of anxiety and sleep disorders rehed on a wide variety of natural products such as opiates, alcohol, cannabis, and kawa pyrones. Use of various bromides and chloral derivatives ia these medical iadications enjoyed considerable popularity early ia the twentieth century. Upon the discovery of barbiturates, numerous synthetic compounds rapidly became available for the treatment of anxiety and insomnia. As of this writing barbiturates are ia use primarily as iajectable general anesthetics (qv) and as antiepileptics. These agents have been largely replaced as treatment for anxiety and sleep disorders. 

In the chemical shift range for alkenes and aromatic and heteroaromatic compounds enol ether fragments (furan, pyrone, isoflavone, 195-200 Hz) ... 

A different type of tautomeric relationship exists between compounds of types 323 and 324. Both types of structure can be isolated, pyridones (324, Z = N—Me) and pyrones (324, Z = 0) being formed when 323 (Z = N—Me or 0) is heated with palladium on charcoal in ethylene glycol. Similar isomerizations in the quinol-4-one series have been reported."... 

In the hands of Collie and Tickle in 1899 this reaction gave the first crystalline pyrylium salts. The salt character of the compounds was proved by conductivity measurements the basicity of 2,6-dimethylpyrone was found to be a little higher than that of urea. Basicities of other pyrones decrease in the order 2,6-dimethyl-> 2-phenyl-6-methyl-> 2,6-diphenylpyrone, paralleling the dipole moments. These hydroxypyrylium salts hydrolyze in water to pyrones. " The formation of salts of 2,6-dimethylpyrone with organic acids was investigated by Kendall,and with mineral acids by Cook. 11 ... 

By 0-acylation with 2-methyl-1,3-dioxolenium fluoroborate, which reacts as 0-acetyl ethylene oxide, 2,6-dimethyl-4-pyroiie is converted into 4-acetoxy-2,0-dimethylpyrylium fluoroborate (24, Y = 0, R = Ac, X=BT 4). The alleged compound with this structure which has been obtained from 8 and acetyl fluoroborate is, in fact, the BF3-complex of the pyrone. 

A related reaction is the acylation of yA disuhstituted benzyl ketones to isobenzopyrylium salts the unsubstituted compounds yield 4-pyrones as shown in Section II,D,3,a. Another related acylation converts unsaturated esters into 2-p3U ones, e.g., ethyl, jS-dimethyl-acrylate into 4,6-dimethyl-2-pyrone. ... 

Development of base-catalyzed Diels-Alder reaction of 3-hydroxy-2-pyrone and its application to synthesis of bioactive compounds 99YGK84. 

Synthesis and reactivity in aqueous medium of pyronoids, mono- or polycyclic compounds with 2- or 4-pyrone fragments 99H(50)611. 

A careful assessment of the constitution of compound 10 led to the development of a rather efficient strategy featuring the Diels-Alder reaction (see Scheme 3). Although the unassisted intermole-cular reaction between 3-hydroxy-2-pyrone (16)23 and a,/ -unsatu-rated ester 17 is unacceptable in terms of both regioselectivity and chemical yield, compounds 16 and 17 combine smoothly in refluxing benzene and in the presence of phenylboronic acid to give fused bicyclic lactone 12 (61% yield) after workup with 2,2-... 

Okamura H., Iwagawa M. and Nakatani M. Development of Base Catalyzed Diels-Alder Reaction of 3-Hydroxy-2-Pyrone and Application to Synthesis of Biologically Active Compounds Org. Chem. Japan 1999 57 84... 

Posner G. H. Stereocontrolled Synthesis of Functionalized Cyclohexenes Via Diels-Alder Cycloadditions of 2-Pyrones and 2-Pyridones-Applications to Synthesis of Physiologically Active Compounds in Stereocontrolled Org. Synth. 1994 177, Ed. Trost B. M., Pb. Blackwell Oxford... 

Pyridoxal 157,158,253 Pyridoxamine 253 Pyridoxine 253 Pyrimidines 266,438, 439 Pyrocatechol see 1,2-Dihydroxybenzene I ocatecholsulfophthalein 398 I ocatechol violet reagent 398 Pyrolysis of organic compounds 92, 96 a,y-Pyrone derivatives 288 Pyrrole alkaloids 66 Pyrrole derivatives 266, 269, 270 Pyruvic acid 426... 

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