- Determination of 4-Hydroxy-2,5-dimethyl-3(2H)-furanone and 2(or 5)-Ethyl-4-hydroxy-5(or 2)-methyl-3(2H)-furanone in Pentose Sugar-Based Maillard Model Systems by Isotope Dilution Assays
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The formation of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) and 2(or 5)-ethyl-4-hydroxy-5(or 2)-methyl-3(2H)-furanone (EHMF) from pentose sugars was studied in Maillard model systems. The amounts generated at 90°C for 1 h were determined by isotope dilution assay (IDA). The internal standards used for IDA, i.e., [13C2]HDMF and [2H3]EHMF, were prepared in good overall yields in three steps: addition of labeled acetaldehyde or propionaldehyde to tert-butyloxycarbonyl (Boc)-protected and lithiated 3-butyn-2-ol; oxidation of the Boc-protected diol with permanganate to 1,2-dione; and finally cyclization to the target molecules after removal of the protective groups under acidic conditions. Quantitative data confirmed previous findings that HDMF and EHMF are preferentially formed in the presence of glycine and L-alanine, respectively. The yields obtained were 2.6-5.1 μg of HDMF and 6.8-10 μg of EHMF per mmol pentose. Formation of both furanones was favored in phosphate-buffered solutions at pH 7 compared to pH 5, particularly in the presence of an excess of amino acid. These data are well in agreement with the previously proposed formation mechanism of HDMF and EHMF via Strecker-assisted chain elongation of the pentose moiety. However, both furanones were also produced to a lesser extent by sugar fragmentation-condensation reactions.
- Blank, Imre,Fay, Laurent B.,Lakner, Frederick J.,Schlosser, Manfred
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- Chemical and Enzymatic Syntheses of 6-Deoxyhexoses. Conversion to 2,5-Dimethyl-4-hydroxy-2,3-dihydrofuran-3-one (Furaneol) and Analogues
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6-Deoxy-D-fructose 1-phosphate (6-deoxyF-1-P) forms when a solution containing D-fructose 1,6-diphosphate (FDP) and D-lactaldehyde is treated with the enzymes aldolase and triosephosphate isomerase (Scheme I).This transformation involves three reactions: aldolase-catalyzed cleavage of FDP to a mixture of dihydroxyacetone phosphate and D-glyceraldehyde phosphate, triosephosphate isomerase catalyzed equilibration of dihydroxyacetone phosphate and D-glyceraldehyde phosphate, and aldolase-catalyzed condensation of dihydroxyacetone phosphate and D-lactaldehyde to 6-deoxyF-1-P.An analogous process converts a mixture of FDP and L-lactaldehyde to 6-deoxysorbose 1-phosphate (6-deoxyS-1-P).Aldolase-catalyzed reaction of dihydroxyacetone phosphate, prepared separately, with D-lactaldehyde yields 6-deoxyF-1-P directly; similar reaction of dihydroxyacetone phosphate with α-hydroxybutyraldehyde yields a mixture of 6-methyl-6-deoxyhexose 1-phosphates.Acid-catalyzed hydrolysis of the sugar phosphates releases the corresponding free sugars.A mixture containing 6-deoxyhexoses is formed directly by base-catalyzed aldol condensation of dihydroxyacetone and D,L-lactaldehyde.Treatment of any of the 6-deoxyhexoses with acids generates 2,5-dimethyl-4-hydroxy-2,3-dihydrofuran-3-one (Furaneol, a flavor principle).Furaneol can also be prepared in moderate yields by hydrogenolysis of FDP and other hexose phosphates in alkaline media.
- Wong, Chi-Huey,Mazenod, Francois P.,Whitesides, George M.
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p. 3493 - 3497
(2007/10/02)
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- Process for making furanones
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This deals with a process for making furanones having the formula: STR1 wherein R represents a hydrogen atom or the methyl or ethyl group.
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