Dihydroxyacetone solution

Dihydroxyacetone phosphate (82) is a substrate for a-glycero-phosphate dehydrogenase, aldolase, and triose phosphate isomerase, and its O-alkyl ethers are intermediates in the biosynthesis of phospholipids. In neutral aqueous solution at 20 °C, dihydroxyacetone phosphate exists as an equilibrium mixture of the keto (82), gem-d o (83), and enol (84) forms, as shown by n.m.r. spectroscopy. The proportion of (82) to (83)... 

Dihydroxyacetone is not stable under the basic conditions preferred for oxidation of the primary function to give hydroxypyruvic acid (reaction e). Under acidic conditions the rate of oxidation of a 1 mol I l aqueous solution is veiy slow (5 mol h l mol i(Pt)). On platinum the initial rate of conversion for reduced concentrations of the starting material (0.3 mol whilst retaining the same amount of catalyst, was 42 mol h mol-i(Pt), as might be expected under non-favourable acidic conditions. Hydroxypyruvic acid is evolved with a selectivity of 82% at 40% conversion (see Figure 11). 

A tandem enzymatic aldol-intramolecular Homer-Wadsworth-Emmons reaction has been used in the synthesis of a cyclitol.310 The key steps are illustrated in Scheme 8.33. The phosphonate aldehyde was condensed with dihydroxyacetone phosphate (DHAP) in water with FDP aldolase to give the aldol adduct, which cyclizes with an intramolecular Horner-Wadsworth-Emmons reaction to give the cyclo-pentene product. The one-pot reaction takes place in aqueous solution at slightly acidic (pH 6.1-6.8) conditions. The aqueous Wittig-type reaction has also been investigated in DNA-templated synthesis.311... 

When dihydroxyacetone is heated in aqueous solution with cupric acetate, the product is chiefly oxomalonic acid. Evans and Waring, J. Am. Chem. Soc. 48, 2680 (1926). 

Meyerhof and Schulz86 studied this reaction in trisodium phosphate solution, and regarded it as coming to a triose-hexose equilibrium containing 92 % of hexose. Berl and Feazel67 examined the kinetics of hexose formation from trioses in alkaline solution, and noted that 75-90% of hexulose is formed from DL-glycerose alone, but that the yield is lower (about 60%) when dihydroxyacetone is added in equivalent quantity. Paper chromatog-... 

In alkaline solution, glycolaldehyde gives rise to tetroses.160- 169 Tetroses combine with dihydroxyacetone in alkaline solution to give heptoses, as indicated by the results of paper chromatography.16 43... 

Scheme 4.—Formation of Aromatics from Dihydroxyacetone in Acid Solution.

Show a mechanism for the interconversion of glyceraldehyde-3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) in basic solution ... 

Bismethylenedioxy derivatives of hydroxycorticosteroids are produced by the reaction of the dihydroxyacetone function with formaldehyde (Scheme 5.35). Cortisone (10 mg) is suspended in 5.0 ml of chloroform and 1.3 ml of 12 TV hydrochloric acid and 1.3 ml of a 37% solution of formaldehyde are added. The reaction mixture is stirred at 5°C for 48 h and during this time the steroid dissolves. After washing with 1 N sodium hydroxide solution and drying over sodium sulphate, the mixture is filtered through glass-wool and analysed directly. The derivatives are stable and provide symmetric peaks on SE-30, and make it possible to analyse selectively complex mixtures of steroids with a dihydroxyacetone moiety in the molecule [382]. 

Aldehydes have been formed from alcohols by the use of other oxidizing agents. Dihydroxyacetone has been oxidized with excess cupric acetate to hydroxypyruvic aldehyde in 87% yield. p-Cyanobenzyl alcohol treated at 0° with a chloroform solution of nitrogen tetroxide gives practically pure p-cyanobenzaldehyde (90%). Aromatic alcohols containing nitro groups have been oxidized to the corresponding nitro aldehydes with concentrated nitric acid, e.g., o- and p-nitrobenzaldehydes (80-85%). m-Nitrobenzenesulfonic acid in basic media has been used for the oxidation of substituted benzyl alcohols, most satisfactorily for the water-soluble phenolic benzyl alcohols. Selenium dioxide, or less effectively tellurium dioxide, oxidizes benzyl alcohol slowly to benzaldehyde. ... 

According to Klingensmith and Evans,either of the enantio-morphous acetylribosyl bromides reacts with dihydroxyacetone monoacetate, AcOCHj.CO.CH2OH, in benzene solution, under conditions established by Reynolds and Evans, using iodine as a catalyst after the manner of Helferich, Bohm and Winkler. The reaction gave rise to needle-like clusters of 3,4-diacetyl-D-ribose 3 -acetoxyacetonyl 1,2-orthoacetate (VIb), with in. p. 97-98° (corr.) and [a]o —11.6°, or the corresponding L-compound with the same m. p. and [q ]d -j-11.8°. 

Evans this behavior indicated the presence of acetylribosyl chloride. Since the isomeric n-arabinosyl-dihydroxyacetone tetraacetate of Kreider and Evans, which does not possess an orthoester structure, showed no reaction with hydrogen chloride in chloroform solution, it was concluded by Klingensmith and Evans that the behavior of the ribose derivatives is to be attributed to an orthoester structure. 

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