Hydroxy-2-ethyl-4-pyrone

Startg. m. heated 1 hr. in dioxane containing 80%-H2SO4 2-ethyl-3-hydroxy-4-pyrone. Y 91%. F. e. s. S. Torii et al., Chem. Lett. 1976, 495. 

Butyl)-4-hydroxy-3-ethyl-2-pyrone (Germicidin) [Reduction of a Ketone Carbonyl to a Methylene Group in a Multifunctional Compound].423 A... 

SYNS 2-ETHYL-3-HYDROXYAH-PYRAN-4-ONE 2-ETHYL PYROMECONIC ACID 3-HYDROXY-2-ETHYL-4-PYRONE... 

HYDROXY-2-ETHYL-4-PYRONE see ENL 600 HYDROXYETHYL STARCH see HLB400... 

Ethyl pyromeconic acid 3-hydroxy-2-ethyl-4-pyrone Veltol Plus. 

Synonyms 2-Ethyl-3-hydroxy-4H-pyran-4-one 2-Ethyl pyromeconic acid 3-Hydroxy-2-ethyl-4-pyrone... 

Hydroxy-2-ethyl-4-pyrone. See Ethyl maltol 1-(2-Hydroxyethyl)-2-pyrrolidinone 1-(2-Hydroxyethyl) pyrrolidin-2-one. See N-Hyd roxyethyl pyrrol idone N-Hydroxyethylpyrrolidone CAS 3445-11-2 EINECS/ELINCS 222-359-4 Synonyms 1 -(2-Hydroxyethyl)-2-pyrrolidinone 1-(2-Hydroxyethyl) pyrrolidin-2-one N-(2-Hydroxyethyl)-2-pyrrolidone 2-Pyrrolidinone, 1-(2-hydroxyethyl)-Classification Nonaromatic amide Empirical CsHiiN02... 

For the preparation of 4-substituted coumarins, a phenol may be condensed with ethyl acetoacetate under the influence of sulphuric acid. Thus resorcinol (II) readily undergoes this condensation (which is represented diagrammatically above) to give 7-hydroxy-4-methyl-coumarin (III). Note that the coumarins, like all 2 pyrones, are systematically lactones. 

Pyrone, 3-hydroxy-2-methyl Sd (roasted) Pyrrole, 1-5-dimethyl Sd (roasted) Pyrrole, 1-ethyl Sd (roasted) ... 

Dioxo-4-(4-hydroxy-6-methyl-2-pyron-3-yl)butyric acid ethyl ester Extr 5 x 10"1 151... 

Hydroxy-2-methyl-4-pyrone 5-Ethyl-2(5H)-furanone a-TerpinoIene Octanal ... 

In order to prepare the cyclohexenaldehyde 8, 3-hydroxy-2-pyrone 14 and ethyl 4-hydroxy-2-methyl-2-butenoate 15 are subjected to a Diels-Alder reaction in the presence of phenylboronic acid which arranges both reactants to the mixed boro-nate ester 19 as a template to enable a more efficient intramolecular Diels-Alder reaction with optimal control of the regiochemical course of the reaction. Refluxing in benzene affords the tricyclic boronate 20 as primary product. This liberates the intermediate cycloadduct 21 upon transesterification with 2,2-dimethylpropane-l,3-diol which, on its part, relaxes to the lactone 22. Excessive i-butyldimethyl-silyltriflate (TBSTf) in dichloromethane with 2,6-lutidine and 4-7V,A-dimethyl-aminopyridine (DMAP) as acylation catalysts protects both OH goups so that the primary alcohol 23 is obtained by subsequent reduction with lithiumaluminum-hydride in ether. 

Treatment of MI-220 or MI-221 (R = H, CH3) with aromatic amines in water gives l-aryl-5-hydroxy(or methoxy)-4-pyridone-2-carboxylic acids, which are readily decarboxylated to XII-223, (R = H, CH3) or converted to ethyl esters."" 2-Hydroxymethyl-S-methoxy-4-pyrone, a monomethyl ether of kojic acid, and 2-dialkylaminoethylamines in water give l-(2-dialkylaminoethyl)-2-hydroxymethyl-5-methoxy-4-pyridones (MI-224 R = CH3,C2Hs). Natural maltol glucoside and ammonia or primary amines give the corresponding pyridones (XU-225) when boiled in methanol. ... 

Ethyl n-butyroacetate, on treatment with sodium bicarbonate, gives the dehydroacetic acid homolog W-241,which, on treatment with 90% H2S04, is converted to 4-hydroxy-6-propyl-2-pyrone, which gives 4-hydroxy-6- -propyI-2-pyridone in low yield when treated with ammonia. ... 

Although ketones, including ethyl acetoacetate and several related compounds, react with malonyl chloride to form chloropyranodioxins (tMs section, p. 661), 1,3-diketones give pyrones. It was proposed originally that benzoylacetone forms the 4-hydroxy-2-pyrone that tautomerizes to the 2-hydroxy-4-pyrone... 

Methyl-l-phenyl-4-benzoylpyrazolone ( 27 14 2 2 3-Acetyl-2-hydroxy-6-raethyl-4-pyrone (dehydracetic acid) (CgH3E>3) 6-Ethyl-2-hydroxy-3-propionyl-4-pyrone... 

Ethyl 4-phenyl-2-methyl-2-hydroxy-3-butynecarboxylate dissolved in a 1 1 mixture of coned. H2SO4 and glacial acetic acid, then heated up to 1 hr. on a steam bath 4-methyl-6-phenyl-2-pyrone. Y 83.3%. F. e., also at room temp, over a period of several days, s. K. E. Schulte, J. Reisch, and O. Heine, Arch. Pharm. 294, 234 (1961). 

The products of catalytic reduction of chromone-2-carboxylic acids or esters depend partly on the catalyst used, the amount of hydrogen present and the conditions of reaction. Ethyl chromone-2-carboxylate is reduced (in 86 per cent yield) to the corresponding chromanone in the presence of Raney nickel and hydrogen at a pressure of 50 Ib/in [184]. The 5-hydroxy analogue is similarly reduced at 80°C and 30 Ib/in in 44 per cent yield [8]. A nitro group on the benzene ring is more readily hydrogenated than the pyrone double bond (10 atmospheres, platinum-charcoal or palladium-charcoal catalyst) [24,40]. 

Reactions of chromones 230 with acetoacetamide and ethyl acetoacetate in ethanol in the presence of ammonium acetate proceed at the C-2 atom of the chro-mone system with pyrone ring-opening and subsequent cycUzation to 252. Similar reaction with p-aminocrotononitrile gave 5-hydroxy-2-methyl-5-(polylluoroalkyl)-5ff-chromeno[4,3- ]pyridine-3-carbonitriles (253a) [129]. Three-component reaction between chromones 230, dimedone, and AcONH, is accompanied by detrifluoroacetylation and leads to 254 in low yields [130] (Schane 82). 

Benzylmalonyl chloride and ethyl acetoacetate refluxed 3-4 hrs. in dry benzene ethyl 3-benzyl-4-hydroxy-6-methyl-2-pyrone-5-carboxylate. Y 61%. F. e. and methods s. K.-H. Boltze and K. Heidenbluth, B. 91, 2849 (1958). 

Finally, in the context of a recent total synthesis of smyrindiol 69 starting from 2,4-dihydroxybenzaldehyde, the pyrone ring was generated by reduction of the ethyl (2-hydroxyphenyl)-propiolate 67 with the Lindlar catalyst (Scheme 29) [122]. The resulting orf/zo-hydroxy-(Z)-cinnamate ring-closed immediately to the corresponding coumarin 68. 

Lithio-2-(2,2-dimethoxyethyl)-l,3 dithian, when it reacted with ketcmes and epoxides, led to intermediates which were converted in somewhat low yield into 3-furanones and dihydro-y-pyrones, respectively. " 2-Methyl-2-lithio-dithian reacted efficiently with spiro-epoxide groups at positions 3 and 17 in steroids. The products obtained in this manner were further elaborated for example, 3a-ethyl-30-hydroxy-5a-cholestane, " 3-acetonyl-A -androstane, and both isomers of 17-acetonyltestosterone " were prepared. The carbon skeleton, including the S-lactone ring, of pestalotin... 

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