Aldehydes glycols

Oxidation. Olefins in general can be oxidized by a variety of reagents ranging from oxygen itself to ozone (qv), hydroperoxides, nitric acid (qv), etc. In some sequences, oxidation is carried out to create a stable product such as 1,2-diols or glycols, aldehydes, ketones, or carboxyUc acids. In other... 

OxythaHation reactions of olefins provide useful synthetic routes to products, eg, glycols, aldehydes, and ketones (31) ... 

Mino and Kaizerman [12] established that certain. ceric salts such as the nitrate and sulphate form very effective redox systems in the presence of organic reducing agents such as alcohols, thiols, glycols, aldehyde, and amines. Duke and coworkers [14,15] suggested the formation of an intermediate complex between the substrate and ceric ion, which subsequently is disproportionate to a free radical species. Evidence of complex formation between Ce(IV) and cellulose has been studied by several investigators [16-19]. Using alcohol the reaction can be written as follows ... 

Transfer of glycolic aldehyde from xylulose 5-phosphate onto ribose 5-phosphate or the first transketolase reaction. The next reaction, which is catalyzed by transketolase, involves the pentose phosphates produced by the foregoing reaction (the transferable moiety is shown in the box) ... 

Transfer of glycolic aldehyde from xylulose 5-phosphate onto erythrose 4-phosphate or the second transketloase reaction. This reaction is related to the first transketolase reaction and is catalyzed by the same enzyme. The only distinction is that erythrose 4-phosphate acts as an acceptor for glycolic aldehyde ... 

A ray of hope appeared when a synthetic route was developed in the laboratory of Albert Eschenmoser in Zurich, leading in good yields to ribose-2,4-diphosphate (in racemic form). The starting material was glycol aldehyde, which was phospho-rylated in the 2-position and then incubated with formaldehyde. Unfortunately the synthetic conditions are only those of a modern laboratory, but could the reaction have taken place on the primeval Earth (Muller et al., 1990). 

The synthesis of pentose-2,4-diphosphate referred to above gave the best yields of a ribose derivative. Thus, the search for an effective synthesis leading to necessary starting materials such as glycol aldehyde phosphate (GAP) was important Krishnamurthy et al. (1999, 2000) reported new synthetic routes to GAP glycol aldehyde is allowed to react with amidotriphosphate (AmTP) in dilute aqueous solution. The triphosphate derivative is formed from trimetaphosphate and NH4OH. 

Another example of the ability of proteinogenic amino acids, small peptides, and amines to catalyse the formation of new C-C bonds has been demonstrated by Weber and Pizzarello they were able to carry out model reactions for the stereospecific synthesis of sugars (tetroses) using homochiral L-dipeptides. The authors achieved a D-enantiomeric excess (ee) of more than 80% using L-Val-L-Val as the peptide catalyst in sugar synthesis (in particular D-erythrose) via self-condensation of glycol aldehyde. 

What importance could vinylphosphonic acid have for the synthesis of important biomolecules Its photolysis gives many oxidized products, including phosphoac-etaldehyde. This analogue of glycol aldehyde phosphate seems to be of interest its formation involves the recombination of hydroxyl radicals with vinylphosphonic acid radicals. 

Ugi five-center three-component reaction of pipecolinic acid and glycol aldehyde dimer with isocyanides gave a 1 1.7-2.1 diastereomeric mixture of l-oxoperhydropyrido[2,Tc][l,4]oxazine-9-carboxamides 397 (Scheme 35) <20010L4149>. Using CF3CH2OH as solvent is critical for the reaction. When 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid was employed, 1,3,4,6,11,11 a-hexahydro-[ l,4]oxazino[4,3+]isoquinoline-4-carboxarnide was formed. 

Chamow, S.M., Kogan, T.P., Venuti, M., Gadek, T., Harris, R.J., Peers, D.H., Mordenti, J., Shak, S., and Ashkenazi, A. (1994) Modification of CD4 immunoadhesin with monomethoxypoly (ethylene glycol) aldehyde via reductive alkylation. Bioconjugate Chem. 5, 133-140. 

Considerable interest remains in catalyzed hydrogen-transfer reactions using as donor solvents alcohols, glycols, aldehydes, amides, acids, ethers, cyclic amines, and even aromatic hydrocarbons such as alkylben-... 

FIGURE 12-3 Pathways of norepinephrine degradation. Unstable glycol aldehydes are shown in brackets. COMT, catechol-O-methyltransferase. 

Complex 64 is unstable at room temperature even as a solid and is easily hydrolyzed in neutral water to produce glycol aldehyde (Eq. (17)). In 0.1 M HC104, 64 produces glycol aldehyde and acetic acid in a ca. 9 1 ratio. 

These reversible polymerisations of aldehydes are to be distinguished from the condensations which they can also undergo. Thus formaldehyde is converted by quite weak alkalis (Ca(OH)2, CaC03) into glycollic aldehyde and glyceraldehyde, and further into a mixture of hexoses (Butlerow, 0. Loew) from which E. Fischer isolated the so-called... 

The reason why the acyloin synthesis is especially characteristic of aromatic aldehydes, depends on the circumstance that in the aromatic series the tertiary carbon atom in the ring does not allow of the aldol condensation, a reaction for which conditions are otherwise much more favourable. The simplest example of the acyloin condensation, moreover, was already encountered in the case of formaldehyde (p. 218) glycollic aldehyde is the simplest acyloin. Acyloin compounds are also produced, in the aliphatic series, by the action of sodium or potassium on esters, and hence are also formed as by-products in the acetoacetic ester synthesis (Bouveault, Scheibler). 

At even higher temperature, the polysaccharides decompose further by extensive C-C bond breaking. This leads to the formation of C2 4 oxygenates such as glycol aldehyde, acetic acid and hydroxyacetone (CH3-CO-CH2OH). The formation of these products can be rationalized by a series of reactions that include,... 

Serine has been prepared by the Strecker method from glycol-aldehyde 1 and from ethoxyacetaldehyde,2 3 by the condensation of ethyl formate with ethyl hippurate followed by reduction and hydrolysis,4 5 from the reaction product of chloromethyl ether with ethyl sodium phthalimidomalonate,6 and by amination of a-bromo-/3-methoxypropionic acid with subsequent demethyla-tion.7... 

Cramer, the discoverer, showed that, when serine was treated with nitrous acid, it was converted into glyceric acid, and he recognised it as an aminolactic acid. It was regarded as a-amino-jS-oxypropionic acid, but this was only definitely proved when it was synthesised by Fischer and Leuchs in 1902 from glycollic aldehyde, hydrogen C anide and ammonia, which is the first instance of the employment of Strecker s method to build up oxyamino acids from oxyaldehydes. 

The a-oxidation pathway ofTV-nitrosodiethanolamine metabolism (Figure 2) leads to the formation of an a-hydroxynitrosamine that rapidly decomposes, producing glycol aldehyde, acetaldehyde, ethylene glycol and molecular nitrogen. The latter is assumed to arise from a reactive (2-hydroxyethyl)diazonium ion, which probably is responsible for the formation of 2-hydroxyethylated adducts in DNA (Scherer et al., 1991 Loeppky etal., 1998 Loeppky, 1999). 

The metabolism of 7V-nitrosodiethanolamine by a-hydroxylation, which is a cytochrome P450 (CYP)-mediated pathway, was not detected in liver preparations from uninduced male Fischer 344 rats (Farrelly et al., 1984,1987). The existence of a-hydroxylation was proved later, notably by the formation of glycol aldehyde in liver microsomes from rats pretreated with CYP2E1 inducers. The microsomal metabolism of N-nitrosodiethanolamine was slower by a-oxidation than by [3-oxidation (Loeppky, 1999). Bioactivation tests of jV-nitrosodiethanolamine in V79 Chinese hamster cells showed that cytotoxicity was observed only in cells transfected with human CYP2E1 but not in cells expressing CYP2B1 or in the controls (Janzowski et al., 1996 Loeppky, 1999). 

---