Monosaccharide reaction with amino compound

Maltol 337 is one of the degradation products in monosaccharide solutions with amino acids forming Amadori compounds but not in the solution of monosaccharides alone. Heated solutions of monosaccharides yield 335, the logical precursor of 337, but not 337 itself. On the basis of the molecular mechanics calculation indicating that 335 adopts the conformation unfavorable for dehydration into 337, a possible route via the dehydrated product 336, an ortho-elimination product, has been postulated as a more favorable alternate reaction pathway [277]. 

Amino-2-deoxyaldohexoses, 1-amino-l-deoxyketohexoses, and their V-alkyl and JV-aryl derivatives react with /3-dicarbonyl compounds, giving substituted (tetrahydroxybutyl)pyrroles. It is, most probably, a general reaction of 2-amino-2-deoxyaldoses and 1-amino-l-deoxyketoses which parallels the formation of (polyhydroxyalkyl)furans from nonnitrogenous monosaccharides. In the reactions with amino sugars in alkaline media, simpler pyrrole compounds lacking the tetrahydroxybutyl chain are also obtained. 

Amino acids may be involved in biochemical reactions of this type, through their conversion into glycosylamines by reaction with the monosaccharides. The glycosylamines may react directly with the /3-dicarbonyl compound, or after its Amadori rearrangement to the amino sugar. 

Seibel et al. [36] reported, for the first time, the use of microwave heating in the glycosylation of amino acids. They performed glycosyl transfer reactions of perace-tylated monosaccharides (glucose and galactose) and disaccharides (maltose and lactose) with N-9-fluorenylmethoxycarbonyl-L-serine benzyl ester in the presence of iron trichloride with short reaction times (4 min, compared with 5-10 h by conventional heating) and with improved yields (52-61% compared with 10-31% by conventional heating). It is worthy of note that in these reactions heavy metal compounds, for example silver trifluoromethanesulfonate, mercury dibromide and di-cyanide, or boron trifluoride-diethyl etherate, can be replaced by the environmentally safe promoter iron trichloride. 

Difficulties of this sort have been reported, e.g., in the extraction of phenols which had been converted to azo dyes on the adsorbent layer [623]. The reaction of sulphonamides with a diazonium reagent has been taken to completion by adding excess reagent again after having extracted the coloured product [69]. The determination of monosaccharides with benzidine-glacial acetic acid has been carried out similarly [38]. The method has been used also for the quantitative analysis of amino acids, after colour reaction with ninhydrin [42, 95] corticosteroids, after reaction yielding formazans [64] and of cannabinols after conversion into azo compounds [370]. 

In an extensive series of studies, Yoshikawa,Yano and co-workers have confirmed that various kinds of aldose can be complexed with nickel and amino compounds such as diamines and amino acid in a methanolic solution [43]. They studied the nickel(ll) complexes coordinating N-glycosides derived from diamine and monosaccharide. The structure of the complex was determined from three-dimensional X-ray data [43 d]. Their further studies elucidated that aldoses can be epimerized by reaction systems containing a nickel/diamine complex. This novel epimerization proceeds through an alternative mechanism that is definitely distinct from the epimerization mechanism by reversible enolization that was introduced in Sect. 2.1. It results in the formation of an equilibrium mixture of the two epimers. According to their study [ 39], three significant pecu-harities of this epimerization are ... 

The three derivatives of furfuraldehyde (CLIV, CLV and CLVII) form the basis of a number of colour tests for monosaccharides (p. 56) and are also responsible for many of the coloured products produced with different sprays on paper chromatograms (p. 56). It is probable that these furan compounds are responsible for the Mciillard reaction , or browning effect when aqueous solutions of reducing sugars are heated with amino acids, a reaction which is believed to occur in food preservation. Indeed (CLV) is an important precursor in the formation of the brown colour which develops when aqueous solutions of glycine are heated with glucose. 

The most general methods for the syntheses of 1,2-difunctional molecules are based on the oxidation of carbon-carbon multiple bonds (p. 117) and the opening of oxiranes by hetero atoms (p. 123fl.). There exist, however, also a few useful reactions in which an a - and a d -synthon or two r -synthons are combined. The classical polar reaction is the addition of cyanide anion to carbonyl groups, which leads to a-hydroxynitriles (cyanohydrins). It is used, for example, in Strecker s synthesis of amino acids and in the homologization of monosaccharides. The ff-hydroxy group of a nitrile can be easily substituted by various nucleophiles, the nitrile can be solvolyzed or reduced. Therefore a large variety of terminal difunctional molecules with one additional carbon atom can be made. Equally versatile are a-methylsulfinyl ketones (H.G. Hauthal, 1971 T. Durst, 1979 O. DeLucchi, 1991), which are available from acid chlorides or esters and the dimsyl anion. Carbanions of these compounds can also be used for the synthesis of 1,4-dicarbonyl compounds (p. 65f.). 

In addition to the common pathways, glycolysis and the TCA cycle, the liver is involved with the pentose phosphate pathway regulation of blood glucose concentration via glycogen turnover and gluconeogenesis interconversion of monosaccharides lipid syntheses lipoprotein formation ketogenesis bile acid and bile salt formation phase I and phase II reactions for detoxification of waste compounds haem synthesis and degradation synthesis of non-essential amino acids and urea synthesis. 

In another approach, Hindsgaul et al. reported a combinatorial strategy to obtain glycohybrids (Scheme 5) [8]. Glycohybrids are derived from monosaccharides via a Michael reaction, followed by the derivatization of the carbonyl group with several amino acids. This chemistry was further extended to the solution phase parallel synthesis to obtain a library of several compounds. 

The reactions of monosaccharides (including glycosylamines) with i8-dicarbonyl compounds are interesting from the biochemical point of view, because they involve three of the major components (carbohydrates, lipides, amino acids) of living matter and because some of them can take place under physiological conditions. Although the study of these reactions... 

No definitive conclusions can be drawn as to the course and mechanism of the reactions, but our present knowledge points to the occurrence of an aldol reaction of the aldehyde form of the monosaccharide with the activated methylene group of the /3-dicarbonyl compound. This is probably the first step in the reaction. The products of the aldol reaction can be isolated by protecting the hydroxyl group or amino group next to the reducing function of the monosaccharide. 

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