4- Hydroxy-3-hydroxymethyl-4//-pyran

The major pathways for the fragmentation of kojic acid (81,5-hydroxy-2-hydroxymethyl-pyran-4-one), are shown in Scheme 14 support for each route was provided by the appearance of metastable ion peaks (67MI22203). An RDA cleavage followed by loss of a CH2OH radical produces ion (81a), m/e 69, the structure of which was substantiated by deuteration experiments. The ion at m/e 97 arises by extrusion of CO from the molecular ion and loss of HO- from the side chain structures (81b) and (81c) were proposed. Decomposition of [M]t occurs to give ethylene and an HC=0 fragment. The initial stage involves loss of a -CHO radical from the hydroxymethyl substituent, a process which has... 

Recently, only the conformational analysis of 4-hydroxy-tetrahydro-pyran 38 and of 2-(hydroxymethyl)-tetrahydropyran 39 was published (98JCS(P2)1751). The low temperature i I NMR study of 38 gave 8.5%... 

Hydroxymethyltetrahydropyran. Tetrahy-dro-2-(hydroxymethyl)pyran. 5-Hydroxy-methyl-S-valerolactone [100-72-1]... 

ZaR AR, lS,%aR -Tetrahydro-7-hydroxy-2,2-dimethyl-4,7-methano-l, 3-dioxolo[4,5-c]oxepin-6(4//)-one, Q-10 Tetrahydro-3-hydroxy-5-hydroxymethyl-3-furancarboxylic acid, T-26 2,3,3a, 9a-Tetrahydro-3-hydroxy-6-imino-6/ -furo[2, 3 4,5]oxazolo[3,2-a]-pyrimidine-2-methanol, C-170 Tetrahydro-5-hydroxy-3-methylene-2-furanmethanol, D-629 7,8,9,10-Tetrahydro-8-hydroxy-3-methyl-6,9-epoxy-2ff,6ff-pyrimido[2,l-6]-[l,3]oxazocin-2-one, A-715 Tetrahydro-2-hydroxy-6-methylpyran, H-144 Tetrahydro-2-(hydroxymethyl)pyran, T- ... 

Veverka M. Kralovicova E. (1990) Synthesis of Some Biologically Active Derivatives of 2-Hydroxymethyl-5-hydroxy-4H-pyran-4-one, Collect. Czech. Chem. Commun., Vol.55, pp.833-40. 

Kojic acid — see also Pyran-4-one, 5-hydroxy-2-hydroxymethyl-, 3, 611 acylation, 3, 697 application, 3, 880 occurrence, 3, 692 reactions, 3, 714, 715 with amines, 3, 700 with phenylhydrazine, 3, 700 synthesis, 3, 810 Kokusagine occurrence, 4, 989 Kokusaginine occurrence, 4, 989 synthesis, 4, 990 Koopmans theorem, 2, 135 Kostanecki-Robinson reaction chromone and coumarin formation in, 3, 819-821 mechanism, 3, 820 flavones, 3, 819... 

Pyran-4-one, 3-ethoxy-2-methyl-, 3, 612 IR spectra, 3, 595 Pyran-4-one, 2-hydroxy-tautomerism, 3, 642 Pyran-4-one, 3-hydroxy-appiication, 3, 880 synthesis, 2, 91 3, 815 Pyran-4-one, 5-hydroxy-2-hydroxymethyl- C NMR, 3, 588 mass spectra, 3, 611... 

Kojic acid, 5-hydroxy-2-(hydroxymethyl)-4//-pyran-4-one1 (II), is produced from carbohydrate sources in an aerobic process by a variety of microorganisms. The acid was discovered in 1907, its structure was established in 1924, and its chemical synthesis from D-glucose was achieved in 1930. Since then, a considerable amount of study has been devoted to the biosynthesis of kojic acid, and numerous publications have dealt with its chemical and biological properties. After nearly half a century, kojic acid remains a scientists curiosity, without industrial importance. It con-... 

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 basic cycloadduct, butyl 2-methoxy-5,6-dihydro-2//-pyran-6-carboxylate 2a, can be reduced to 6-hydroxymethyl-2-methoxy-5,6-dihydro-2f/-pyran 2b. Both 5,6-dihydro- 2/f-pyrans 2a and 2b can be converted in several ways to sugars, cir-Hydroxy 1 ation or epoxidation, followed by basic (or acidic) opening of epoxides with various nucleophilic reagents leads to various 4-deoxyhexoses 3b [18], Dihydropyran 2b can be transformed in a... 

An especially interesting case [53] is the photochromic pair of enantiomerically stable l,l -binaphthylpyran 8 and 2-hydroxy- 2/-hydroxymethyl-l,l -binaphthy-lene 10. The enantiomers of the pyran 8 can be separated by chromatography... 

C6H6C16 hexachlorocyclohexane (mixed isomers) 608-73-1 572.95 50 936 2 7105 C6H604 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one 501-30-4 531.65 46.933 2... 

Figure 7.1.1. Chromatogram for the pyrotysate ofgtucose obtained by on-line Py-GC/MS. The peak assignments are 1 furan, 2 2-melhylfuran, 3 2,5-dimethylfuran, 4 3-methyl-2-butanone, 5 water, 6 1-hydroxypropanone, 7 hydroxyacetaldehyde, 8 acetic acid, 9 oxopropanoic acid methyl ester, 10 furancarboxaldehyde, 11 1-(2-furanyl)-ethanone, 12 5-methyl-2-furfural, 13 2-hydroxycyclopent-2-en-1-one, 14 2-hydroxy-3-methyl-2-cyclopenten-1-one, 15 2,3-dihydro-5-hydroxy-6-methyl-4H-pyran-4-one, 16 2-methyl-1,3-benzendiol, 17 2,5-dimethyldioxane, 18 2-hydroxy-3-pentanone, 19 5-formyl-2-fufurylmethanoate, 20 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, 21 1,4 3,6-dianhydro-a-D-glucopyranose, 22 5-(hydroxymethyl)-furancarboxaldehyde.

Figure 7.2.1. Cellulose pyrolysate obtained at 59CP C and trimethylsilylated. The separation was done on a methyl silicone with 5% phenyl silicone type column. 1 1,2-dihydroxyethane, 2 2-hydroxypropionic (lactic) acid, 3 hydroxy acetic (glycolic) acid, 4 turanmethanol, 5 peak from silylation reagents, 6 1,3-dihydroxypropanone, 7 1,4-dioxane-2,5-diol, 8 1,3-dioxolane-4,5-diol, 9 1,3-dihydroxybenzene, 10 2-methyl-1,4-dioxane-2,5-diol, 11 1,4-dihydroxybenzene, 12 3-hydroxy-2-(hydroxymethyl)-2-cyclopenten-1-one, 13 2-hydroxy-5-(hydroxymethyl)-4(H)-pyran-4-one, 14 1,2,3-trihydroxybenzene, 15 internal standard, 16 an anhydrosugar, 17 levoglucosan (1,6-anhydro-p-D-glucopyranose), 18 a monosaccharide, 19 an anhydrosugar, 20 an anhydrosugar, 21 1.6-anhydro-P-D-glucofuranose .

Oxidations catalyzed by platinum oxide are now well known in carbohydrate chemistry, and their marked specificity has been examined with profit. From the reaction with D-glucal, a mixture of products was obtained, from which 2-deoxy-D-orob no-hexose and crystalline 2,3-dihydro-3-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one (32) were obtained.47 Related enones have been encountered among... 

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