Glyoxylic acid, sodium salt, reaction

C-Disaccharide analogs of trehalose were recently [20c] prepared by using as a key step an aqueous Diels-Alder reaction between the sodium salt of glyoxylic acid and the water soluble homochiral glucopyranosil-l,3-pentadiene 19 (Equation 6.1). A mixture of four diastereoisomers in a 41 24 21 14 proportion was obtained after esterification with methanol and acetylation. The main diaster-eoisomer 20 was isolated and characterized as benzoyl-derivative. 

White observed a post-irradiation process between glyoxylic acid and hydrogen peroxide in irradiated glycine solutions. Synthetic mixtures of these two compounds reacted similarly, to give equivalent amounts of formic acid, and Hatcher and Holden have shown that reaction (3) is bimolecular no oxalic acid can be detected, and the sodium salt is particu-... 

The most common ester used for pteridine synthesis is ethyl glyoxylate which is commercially available as the ethyl hemiacetal (ethyl 2-ethoxy-2-hydroxyacetate) or as the diethylsulfanyl derivative. Both the pteridin-6-one and the pteridin-7-one may be obtained, and the ratio of isomers can be controlled to some extent by the choice of reaction conditions. This is well illustrated by condensations of pyrimidine-4,5-diamine with ethyl 2-ethoxy-2-hydroxyacetate. At pH 6 a mixture of products is obtained with the 7-isomer predominating. The products may be separated at pH 2 at which pteridin-7(8/7)-one is insoluble and may be collected, whilst the pteridin-6(5//)-one remains in solution as the 7,8-hydrate cation. If the condensation is carried out at pH 10 (2 M sodium carbonate under reflux), the 7-isomer is formed, almost exclusively, as the sodium salt.79 However, if the reaction is carried out at pH 0 (1 M sulfuric acid, 37 °C), the 6-isomer, as its stable covalent hydrate, is formed almost exclusively.80... 

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