Glyoxylate formation

Althongh glyoxalate can be transaminated back to glycine, this is not really considered a biosynthetic ronte for new glycine, becanse the primary ronte for glyoxylate formation is from glycine oxidation. 

Glycine degradation by bovine spermatozoa is thought to go through glyoxylate, formate, and CO2 (Flipse and Benson, 1957). A folic coenzyme, if required here, should be extraordinarily interesting Does the spermatozoon retain the folic coenzyme used in the synthesis of its DNA ... 

In a situation where severe steric hindrance e.g., 16,16-dimethyl-20-keto-pregnanes) prevents enol acetate formation, an alternate scheme has been devised. Condensation of ethyl oxalate at C-21 produces, after hydrolysis, the 21-glyoxylic acid this on treatment with acetic anhydride and a strong acid catalyst such as perchloric acid gives both lactone acetates. 

Reductive alkylation has been used to prepare a-amino acids suitable for lactam formation and further elaboration. In a single step a carbobenzyloxy group was removed, and alkylation with glyoxylic acid hydrate was achieved (18). 

Iminium ions bearing an electron-withdrawing group bonded to the sp carbon of the iminium function are very reactive dienophiles. Thus, iminium ions 26 generated from phenylglyoxal (Scheme 6.15, R = Ph) or pyruvic aldehyde (R = Me) with methylamine hydrochloride, react with cyclopenta-diene in water at room temperature with good diastereoselectivity [25] (Scheme 6.15). If glyoxylic acid is used, the formation of iminium salt requires the free amine rather than the amine hydrochloride. 

Both aerobic and reductive pathways were suggested for the degradation of 1,1,2-trichlo-roethane (Castro and Belser 1990)—a dominant aerobic pathway to chloroacetate and glyoxylate, and simultaneously a minor reductive reaction, which must also involve an elimination reaction with the formation of chloroethene (Figure 7.66). 

It has been shown to metabolize trifluoroethene to glyoxylate, difluoroacetate, and the rearranged product trifluoroacetaldehyde (Fox et al. 1990). The last reaction is analogous to the formation of trichloroacetaldehyde from trichloroethene by the same strain (Oldenhuis et al. 1989). 

A Friedel-Crafts-type reaction of phenols under basic conditions is also possible. Aqueous alkaline phenol-aldehyde condensation is the reaction for generating phenol-formaldehyde resin.34 The condensation of phenol with glyoxylic acid in alkaline solution by using aqueous glyoxylic acid generates 4-hydroxyphenylacetic acid. The use of tetraalkylammonium hydroxide instead of sodium hydroxide increases the para-selectivity of the condensation.35 Base-catalyzed formation of benzo[b]furano[60]- and -[70]fullerenes occurred via the reaction of C60CI6 with phenol in the presence of aqueous KOH and under nitrogen.36... 

Cooke and coworkers reported on the synthesis of the amino acid N-benzyl-4-acetylproline (2-889) (Scheme 2.198) [453], as this might represent an interesting synthon for the preparation of bioactive compounds. These authors also used a domino iminium ion formation/aza-Cope/Mannich protocol. Thus, treatment of the secondary amine 2-885 with glyoxylic acid (2-888) primarily provided the corresponding iminium ion, which led to 2-889 in 64% yield as a mixture of diastereom-ers. 

The bromine water test is somewhat more satisfactory for pure tryptophane than the glyoxylic acid test. Hydrogen sulfide may interfere (owing to sulfur formation) and must be boiled out first. The solution to be tested must be acid with acetic acid. 

Measurement of the acidity produced in the periodate oxidation of carbohydrates is confined mainly to the determination of formic acid. Only from unsubstituted ketoses is the formation of such acids as glyoxylic and glycolic to be expected in carbohydrate chemistry.274... 

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