Furaldehyde methyl

Furaldehyde. See Furfural 2-Furaldehyde, 5-methyl-. See Methylfurfural Furale. See Furfural Furan... 

Methyl-5-formylfuran 5-Methyl furaldehyde 5-Methyl-2-furaldehyde 5-Methyl-2-furancarboxaldehyde. See Methylfurfural 2-Methylfuran-3-carboxanilide. See Fenfuram Methyl 2-furancarboxylate. See Methyl 2-furoate... 

Allyl-2-IVIethoxyphenol 2-Furaldehyde Methyl Phenyl Ketone... 

Methyl mercaptan Hydrazine hydrate 5-Nitro-2-furaldehyde... 

The well-known condensation between 2-furaldehyde and acetone in a basic medium yields what is usually called furfurylidene acetone monomer composed of a mixture of 2-furfurylidene methyl ketone, di-2-furfurylidene ketone, mesityl oxide and other oligomers derived from further condensation reactions135. This mixture is then polymerized by the action of an acidic catalyst in the first phase of the reaction a polymer of low molecular weight is produced which on further treatment cross-links to a black insoluble and heat-resistant material136. ... 

Methyl-2-furaldehyde gave a similar overall behaviour, but a penultimate effect was observed in its copolymerization with isopropenylbenzene whereby two molecules of the aldehyde could add together if the penultimate unit in the growing chain was from the olefin. This was borne out by the copolymers composition and spectra. The values of the reactivity ratios showed this interesting behaviour rx = 1.0 0.1, r2 = 0.0 0.1. An apparent paradox occurred the aldehyde, which could not homo-polymerize, had equal probability of homo- and copolymerization and the olefin, which homopolymerized readily, could only alternate. The structure arising from this situation was close to a regular sequence of the type ... 

Chloro-2-(A(-methyIhydrazino)quinoxaline 4-oxide gave 6-chloro-2-[A( -(fur-2-ylmethylene)-A(-methyIhydrazino]- (232, X = O) (2-furaldehyde, dioxane, reflux, 1 h >95%)" or 6-chloro-2-[A(-methyl-A( -(thien-2-ylmethylene) hydrazinojquinoxahne 4-oxide (232, X = S) (2-thiophenecarbaldehyde, dioxane, reflux, 1 h 91%). ... 

Vinas, P., CampiUo, N., Hernandez Cordoba, M., and Candela, M. E. (1992). Simultaneous liquid chromatographic analysis of 5-hydroxymethyl-2-furaldehyde and methyl anthra-nilate in honey. Food Chem. 44, 67-72. 

AW, Acid-washed Choi, Cholesterol DMAP, 4-(Dimethylamino)pyridine DMF, N,/V-Dimethylformamide DMTr, Di(p-niethoxyphenyl)phenyl methyl GalNAc, N-Acetylgalactosamine, 2-acetamido-2-deoxy-D-galactose HMF, 5-Hydroxymethylfur-fural, 5-(hydroxymethyl)-2-furaldehyde INOC, Intramolecular nitrile oxide-alkene cycloaddition Lea, Lewisa Lex, Lewisx MOM, Methoxymethyl MP, p-Methoxyphe-nyl MS, Molecular sieves NIS, N-Iodosuccinimide PCC, Pyridinium chlorochromate PDC, Pyridinium dichromate PMA, Phosphomolybdic acid PMB, p-Methoxybenzyl ... 

Neher and Lewis177 obtained 2-furaldehyde from 2,3,4-tri-O-methyl-L-arabinose by heating with dilute acid after preliminary enolization with alkali. Isbell83 proposed a mechanism for this conversion similar to that for the conversion of tetra-0-methyl-(2-hydroxy-D-glucal) into 5-(hydroxymethyl)-2-furaldehyde XLIV was suggested as an intermediate. In Hurd and Isenhour s178 scheme for the formation of 2-furaldehyde from free pentose, the enol (XLV) of a 3-deoxypentosone was regarded as an inter-... 

Oxidation of II to V is similarly effected by periodic acid.8 Aldehyde V can be saponified and further decarboxylated8 by copper chromite in quinoline to give 5-methyl-2-furaldehyde, affording additional confirmation of the assigned formula. 

D-Xylose and D-arabinose have been treated with a 0.5 M acetate buffer (pH 4.5) at reflux. Besides 2-furaldehyde, some catechols and unique chromones were isolated from the reaction mixture in small proportions. These included 3,8-dihydroxy-2-methylchromone and its precursor, 5,6,7,8-tetrahydro-3,5-dihydroxy-2-methyl-8-oxochromone. A trihydroxy-2-methylchromone was also isolated from the D-xylose reac-... 

Thermolysis of D-fructose in acid solution provides 11 and 2-(2-hydrox-yacetyl)furan (44) as major products. Earlier work had established the presence of 44 in the product mixtures obtained after acid-catalyzed dehydrations of D-glucose and sucrose. Eleven other products were identified in the D-fructose reaction-mixture, including formic acid, acetic acid, 2-furaldehyde, levulinic acid, 2-acetyl-3-hydroxyfuran (isomaltol), and 4-hydroxy-2-(hydroxymethyl)-5-methyl-3(2//)-furanone (59). Acetic acid and formic acid can be formed by an acid-catalyzed decomposition of 2-acetyl-3-hydroxyfuran, whereas levulinic acid is a degradation prod-uct of 11. 2,3-Dihydro-3,5-dihydroxy-6-methyl-4//-pyran-4-one has also been isolated after acid treatment of D-fructose.The pyranone is a dehydration product of the pyranose form of l-deoxy-D-eo f o-2,3-hexodiulose. In aqueous acid seems to be the major reaction product of the pyranone. 

The formation of oxygen-containing heterocyclic compounds is also a consequence of the Maillard reaction. Amines and amino acids have a catalytic effect upon the formation of 2-furaldehyde (5), 5-(hydroxy-methyl)-2-furaldehyde (11),2-(2-hydroxyacetyl)furan (44),2 and 4-hy-droxy-5-methyl-3(2//)-furanone (111) (see Ref. 214). This catalytic effect can be observed with several other non-nitrogenous products, including maltol. The amino acid or amine catalysis has been attributed to the transient formation of enamines or immonium ions, or the 1,2-2,3 eno-lization of carbohydrates. Of interest is the detection of A -(2-furoyl-... 

An effort has also been made to determine the structure of products providing coloration in the Maillard reaction prior to melanoidin formation. The reaction between D-xylose and isopropylamine in dilute acetic acid produced 2-(2-furfurylidene)-4-hydroxy-5-methyl-3(2/f)-furanone (116). This highly chromophoric product can be produced by the combination of 2-furaldehyde and 4-hydroxy-5-methyl-3(2//)-furanone (111) in an aqueous solution containing isopropylammonium acetate. The reaction between o-xylose and glycine at pH 6, under reflux conditions, also pro-duces " 116. Other chromophoric analogs may be present, including 117,... 

The acyclic, enolic compounds 7 and 9 may exist in either cis or trans forms. Methyl ethers of 7 have been isolated in the cis form,8 but it is not known whether the trans forms, which must be acyclic, exist. The relative proportion of isomers is controlled by the geometry of the parent sugar enediol. Although the acyclic forms are readily interconvertible tautomers, it appears that, in acidic medium, further reaction occurs much more rapidly than any equilibrating reactions. Compound 7 undergoes rapid elimination of a second hydroxyl group to give 11. This acyclic product, also, may exist as either a cis or a trans isomer, both forms of which have been isolated.8 The loss of a third molecule of water per molecule occurs after, or simultaneously with, the cyclization of 11 (see Section II, 3 p. 171), and results in formation of 5-(hydroxymethyl)-2-furaldehyde (5). 

The major products formed from hexoses that react in aqueous acidic solution are 5-(hydroxymethyl)-2-furaldehyde, levulinic acid, and polymeric materials. In addition, many minor dehydration products are found. In a study41 of D-fructose, 2-(2-hydroxyacetyl)furan (13), 2-acetyl-3-hydroxyfuran (isomaltol 16), 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, and 3,4,5-trihydroxy-3,5-hexadien-2-one (acetylformoin) were identified. Products not formed solely by dehydration mechanisms include acetone,56 formaldehyde, acetalde-... 

The formation of such chromones as 3,8-dihydroxy-2-methyl-chromone by treating uronic acids or pentoses with dilute acid was reported by Aso,119 and studied by Popoff and Theander,120 who obtained a number of these compounds in 3.5% yield, as well as some catechols. Although nothing is yet known about the mechanism of formation of these compounds, the fact that the chromones contain 10 carbon atoms and are produced both from pentoses and uronic acids suggests that they may be derived from 2-furaldehyde or re-ductic acid, or produced from a decarboxylated intermediate. 

In concentrated sulfuric acid, D-glucuronic acid is dehydrated more slowly than either its 4-O-methyl derivative or D-glucose, probably because of the stability of its lactone. All hexuronic acids, however, eventually produce the same characteristic absorbance that corresponds roughly to a composite of 5-formyl-2-furoic acid, 2-furaldehyde, and reductic acid. It is interesting that a thin-layer chromatographic examination of the reaction products of D-glucuronic acid with 89% sulfuric acid at 70° revealed 5-formyl-2-furoic acid as a major product, but no evidence was obtained for the presence of reductic acid. This result is in distinct contrast to the products obtained in dilute acid solutions, in which 5-formyl-2-furoic acid is produced in very low yield, whereas reductic acid is formed in yields in excess of 10%. 

Because, on treatment with the anthrone reagents,224,225 hexoses and 5-(hydroxymethyl)-2-furaldehyde give solutions having identical spectral characteristics, dehydration is indicated to be the important reaction in this analysis. This conclusion is further supported by the reported isolation228 of 10-furfurylidene-9,10-dihydro-9-oxoanthra-cene (121) after reaction of 2-furaldehyde with anthrone, and by the fact that 121 has an absorption maximum of 600 nm, a value close to that used for pentose estimations. In similar studies,227 9,10-dihydro-10-(5-methylfurfurylidene)-9-oxoanthracene (122) was reported to have been isolated after the reaction of either L-rhamnose or 5-methyl-... 

Similarly, 5-methyl-2-furaldehyde was converted into 3,4,6-tri-deoxy-DL-hex-3-enopyranosides. 4,4,5,5-Tetramethyl-2-(5-methyl-2-furyl)-l,3-dioxolane was oxidized with bromine-water, and the unsat-urated dioxolane resulting was immediately reduced with sodium borohydride, to give a mixture of DL-2-(l,4-dihydroxy-cts-pentenyl)-4,4,5,5-tetramethyl-l,3-dioxolane. Methanolysis gave the known methyl 3,4-6-trideoxy-a-DL-threo- and -en/f/iro-hex-3-enopyranosides, identified by H-n.m.r. spectroscopy.24 ... 

Alternatively, lactone 392 was condensed with 2-furaldehyde, and the aldol adduct was dehydrated to give 394. Treatment of 394 with methanolic sodium methoxide afforded the methyl ester 395, which, after (trialkylsilyl)ation, was transformed by ozonolysis into the unstable keto ester 396. Compound 396 was converted into showdomycin, as well as into some 6-azapseudouridines.261 A number of a,a -dibro-moketones react262 with furan, to give substituted analogs of the bicy-elic ketone 390. Appropriately substituted substrates have been converted,263 by way of Baeyer-Villiger oxidation and treatment of the resulting lactone with tcrt-butoxybis(dimethylamino)methane, into pseudouridines 397 modified at C-5. 

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