2-Methyl-5-hydroxy-4-pyrone

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

SYNS CORPS PRALINE 3-HYDROXY-2-METHYL-4H-PYRAN-4-ONE 3-HYDROXY-2-METHYL-7-PYRONE 3-HYDROXY-2-METHYL-4-PYRONE LARIXIC ACID U3RIXINIC ACID 2-METHYL-3-HYDROXY-4-PYRONE 2-METHYL-3-OXY-7-PYRONE 2-METHYL PYROMECONIC ACID PALATONE TALMON VETOL... 

Oxidation by Acetobacter results in a mixture of the normal isomers of D-arabfno-hexulosonic acid and D-Zt/xo-S-hexulosonic acid, but, in addition, D- r eo-2,5-hexodiulose and 3,5-dihydroxy-2-methyl-7-pyrone (5-hydroxy-maltol) are formed. On the other hand, Glwonobacter cerinus var. ammoniacus Asai also forms D-i/ireo-2,5-hexodiulose having the following constants m.p. 157-159° and [ ]d —85° (in water). ... 

DIELS-ALDER REACTIONS Benzocyclopropene. 1,2-BisC3-tosyIethoxycarbonyl)-diazene. Cyclobutadiene iron tricarbonyl. 1,2-Dicyanocyclobutene. Diethyl ketomalonate. 1,3,4,6-Heptatetraene. 2-Hydroxy-5-oxo-5,6-dihydro-2/f-pyrone. 3-Hydroxy-2-pyrone. Isopropylidene isopropylidenemalonate. Lithium tetra-methylpiperidide. 4-Methoxy-5-acetoxymethyl-o-benzoquinone. 4-Methoxy-5-methyl-o-benzoquinone. frans-l-Methoxy-3-trimethyl-silyloxy-l,3-butadiene. Per-fluorotetramethylcyclopentadiene. 4-Phenyl-l, 2,4-triazoline-3,5-dione. Potassium f-butoxide. 

Two other types of unusual indium(II)-oxygen ligand complexes are known. The polar-ographic reduction of In(acac)3, In(tropolonate)3 or In(pyronate)3 (pyronate = 3-hydroxy-2-methyl-4-pyronate anion) in non-aqueous solution shows a one-electron reduction in each case, corresponding to the formation of a (formally) In complex. Similar behaviour was observed with In(oxine)3, and in some cases a second one-electron reduction was also observed, implying the formation of In species, although in no case was the site of the reduction identified, so that the product may be either [In (acac)3] or [In (acac)2(acac )] (c/. sulfur ligands. Section 25.2.3.4). 

Hydroxy-2-methyl-4-pyrone 3-Hydroxy-2-methyl-y-pyrone. See Maltol... 

Synonyms 3-Hydroxy-2-methyl-4H-pyran-4-one 3-Hydroxy-2-methyl-4-pyrone 3-Hydroxy-2-methyl-y-pyrone Larixic acid Larixinic acid 2-Methyl-3-hydroxy-4-pyrone 2-Methyl-3-oxy-y-pyrone 2-Methyl pyromeconic acid Empirical CeHeOs Formula CH3CsH20(0)(0H)... 

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. 

Synthesis with sacrificial electrodes is employed as a direct method in several other preparations of organometallic compounds and complexes. 3-Hydroxy-2-methyl-4-pyrone derivatives of Sn 1 (and of Zn, Cu, In and Cd as well) were prepared using the metal as an anode. The low oxidation state Sn(II) compound is obtained by direct electrolysis134. 

D. Nematollahi, and Z. Forooghi, Electrochemical oxidation of catechols in the presence of 4-hydroxy-6-methyl-2-pyrone, Tetrahedron 58(24), 4949 953 (2002). 

NMR spectra were measured. As RuCl(H20)(csb)2/02/Me2CHCH0/CH2Cl2/4°C it asymmetrically epoxidised styrene and substituted styrenes with e.e. of up to 30% [798]. Complexes with (csb =lR,2R(-)l,2-diaminocyclohexane with 3-acetyl-4-hydroxy-6-methyl-2-pyrone and salicylaldehyde, 5-chloro-5-methoxy, 5-methoxy and 5-nitrosalicyladehyde) asymmetrically epoxidised styrene as RuCKH O) (csb )2/PhIO/CH3CN [799]. 

A facile one-pot synthesis of furopyrans takes place with aromatic aldehydes, cyclohexyl isocyanide, and 4-hydroxy-6-methyl-2-pyrone in the presence of a solid support such as Montmorillonite K-10 (Equation 62) <2005SC535>. The solvent-free reaction, which is enhanced by microwave irradiation, proceeds much more rapidly under these conditions than by conventional methods <2002TL2293>. The one-pot, three-component reaction is also reported to take place rapidly using water as solvent <2004M589>. 

Soft carbon nucleophiles other than malonate derivatives follow similar patterns of regioselectivity, as shown by the addition of cyclopentadiene anion (equation 211)>os and the highly acidic 4-hydroxy-6-methyl-2-pyrone (equation 212).393... 

The palladium [Pd(Ph3)4]-catalysed 3 + 3-cycloaddition of trimethylenemethane with azomethineimines produced hexahydropyridazine derivatives under mild conditions (40 °C).171 The Lewis acid-catalysed formal oxa-[3 + 3]-cycloaddition of a,f+ unsaturated aldehydes with 6-methyl-4-hydroxy-2-pyrone, 1,3-diketones, and viny-logous silyl esters yielded a variety of pyrones at room temperature.172 Croton-aldehyde has been converted to 6-hydroxy-4-methylcyclohex-l-enecarboxaldehyde by an enantioselective 3 + 3-cycloaddition catalysed by proline. This methodology was used in the synthesis of (—)-isopulegol hydrate, (—)-cubebaol, and (—)-6-hydroxy-4-methylcyclohex-l-ene-1-methanol acetate, an intermediate in the total synthesis of the alkaloid magellanine.173... 

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