Glucose with 2,4-pentanedione

The reactions of D-glucose with 2,4-pentanedione (acetylacetone), diethyl 3-oxoglutarate, ethyl benzoylacetate, ethyl propionylacetate, ethyl butyrylacetate, ethyl isovalerylacetate, and methyl acetoacetate have been effected, with formation of crystalline products. 

On the basis of an intermediate (89), similar to (86), for the reaction of 2-amino-2-deoxy-D-glucose with 2,4-pentanedione, the formation of 2-methylpyrrole has been explained by assuming a concerted elimination initiated by the attack of the hydroxyl ion on the acetyl group, so as to give compound (90), followed by a fission (envisaged as a retroaldol type of reaction) of the tetrahydroxybutyl chain, as shown. 

Reaction of o-glucose with 2,4-pentanedione or ethylacetoacetate in the presence of ZnCl2 gave the respective D-arabino-tetrahydroxybutyl furans 7 and 8 [31] two sugar carbon atoms were utilized in building the furan ring. The alditolyl residues have been oxidatively cleaved to aldehyde or carboxylic acid and can be chemically modified to 9 to prepare hetarylene-carbopeptoid hbraries [32]. 

In the reactions of 2-amino-2-deoxy-D-glucose with some /3-dicarbonyl compounds (such as ethyl acetoacetate, 2,4-pentanedione, or pyruvic acid) in alkaline solution, pyrroles lacking the tetrahydroxybutyl chain are obtained. The loss of this group cannot occur with the already formed (tetrahydroxybutyl)pyrroles, because these compounds, as exemplified by 3-acetyl-2-methyl-5-(D-ora wo-tetrahydroxybutyl)pyrrole (2), remain unchanged at the pH (9-10) of the reaction. The fission of the sugar chain most probably occurs for one of the intermediates of the reaction, for instance (79), and it may be formulated as a concerted-elimination reaction catalyzed by the hydroxyl ion, as indicated in Scheme C. The... 

Cornforth and coworkers and Gottschalk have expressed the view that the reaction of 2-amino-2-deoxy-n-glucose with pyruvic acid (and with 2,4-pentanedione) begins with the formation of a Schiff base [such as (85)], followed by an intramolecular aldol reaction to compounds (86). This interpretation cannot be extended to the reactions of nonnitrogenous sugars, and can only be applied in a modified way to the iV-alkylamino and M-arylamino sugars. Such compounds as (87) or (88) could be the... 

The compound XLII, obtained by the reaction of 2,4-pentanedione (acetylacetone) with D-glucose, also undergoes dehydration easily,8 giving a... 

A 200 mM phosphate-buffered solution, pH 6.9 (100 mL), containing 3-allyl-2,4-pentanedione (700 mg, 50 mmol), glucose (2.16 g, 120 mmol), NADPH (45 mg), glucose dehydrogenase (50 mg) and KRED-102 (50 mg) was stirred at room temperature for 24 h, until gas chromatography (GC) analysis of the crude extracts showed complete reaction. Periodically, the pH was readjusted to 6.9 with NaOH (2 m). 

Because a-dicarbonyl compounds are particularly reactive, Weenen and Apeldoom57 specifically looked for these compounds by means of derivatisation with o-diaminobenzene among the butanol-soluble fragmentation products formed in 15 systems (glucose, fructose, xylose, 3-deoxyglucosone, or fructosylalanine without amine or with alanine or cyclohexylamine 1 h, 100 °C, phosphate buffer, pH 8). Four a-dicarbonyls were obtained glyoxal, 2-oxopropanal, butanedione, and 2,3-pentanedione. 

There is a similar outcome in the reduction of 2,4-hexanedione. As for /J-keto esters, the culture conditions can play an important role in the course of a reaction. If the anaerobic bacterium Clostridium tyrobutyricum is grown on glucose, 2,4-pentanedione is reduced to a mixture of the (4S)- and (4/ )-4-hydroxy-2-pentanone (75 25) and the meso-2,4-diol (2R,45). If crotonate is used as the carbon source, only the (2S,4,V)-2,4-diol is obtained with high enantiomeric ex-... 

This product is probably formed by condensation (involving the Strecker degradation of an amino acid) of pyruvaldehyde with 2,3-pentanedione (Wang et al., 1969). It is formed in the Maillard reaction of the dipeptide Ala-Asp (alanine-aspartic acid) with glucose. 

In the experiments first described, 2-amino-2-deoxy-D-glucose was heated with an excess of the /3-dicarbonyl compound in the absence of solvent. The product so obtained from ethyl acetoacetate, m.p. 142°, [a]n 49.7°, had an analysis corresponding to that for ethyl 2-methyl-5-(D-ara6mo-tetrahydroxybutyl)pyrrole-3-carboxylate and was considered to have this structure (1). In the reaction with 2,4-pentanedione, a material (m.p. 98°, Md — 25.1°) was obtained which was described as 3-acetyl-2-methyl-5-(D-ara5fno-tetrahydroxybutyl)pyrrole (2). Boyer and Furth" repeated the latter reaction, but in methanol solution, and obtained a product, m.p. 133°, whose analytical data were in agreement with those for structure (2). 

Base-catalyzed reactions of amino sugars with 2,4-pentanedione in a nonaqueous solvent (piperidine-triethylamine-methanol) have also been reported. The products obtained under these conditions from 2-amino-2-deoxy-D-glucose are 3-acetyl-2-methyl-5-(D-ami)OTo-tetrahydroxybutyl)-pyrrole (2) (in about 90% yield) and 2-deoxy-2-n(4-oxopent-2-enyl)-amino]-D-glucose (28). Proofs that structure (28) is correct were (a) the ultraviolet absorption, typical of a -amino a,j3-unsaturated ketone, (b) a positive test with the ferric chloride reagent, and (c) quantitative... 

Condensation of 2,3 4,5-di-O-benzylidene-D-ribose or related aldehydo-D-ribose or -D-glucose derivatives with a number of active methylene compounds, e.g., pentane-2,4-dione, gave the expected Knoevenagel condensation products, which all showed antiviral activity and cytotoxicity the most effective against herpes simplex virus was the ribose-2,4-pentanedione derivative (34) titanium... 

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