Oxamates

Following slow dissolution into the soil solution, oxamide undergoes stepwise hydrolysis to Hberate ammonia. Oxamic acid is formed in the first... 

Works on the oxidation of uric acid has unequivocally established the triazine structure > ° (9) of oxonic acid. This is further confirmed by the straightforward synthesis described by Piskala and Gut. ° The reaction of biuret (11) with potassium ethyloxalate yielded a potassium salt (24), that with ethyl oxamate, the amide of oxonic acid (25). Both these compounds were converted to 5-azauracil. An analogous reaction with diethyloxalate which should produce an ester of oxonic acid resulted in a mixture of urethane and parabanic acid, however. 

The formation of methyl(benzylsulfonyl)oxamate 70 as the reactive intermediate in the reaction of arylmethanesulfamide 69 and diethyl oxalate, giving 5-aryl-4-hydroxy-3(2f/)-isothiazolone 71, has been reported (99MI1). 

Oxamidsaure, Oxaminsaure, /. oxamic acid, Oxathyl-. hydroxyethyl-. 

N-Acetylation of Kasugamycinic Acid (9a). A solution of kasugamycinic acid (225 mg.) dissolved in 10 ml. of water was treated with acetic anhydride (0.3 ml.) under cooling sodium bicarbonate was used to keep the pH 7.2 and stirring continued for 30 minutes. The reaction product was passed through Dowex 50W-X2 (H form) and the column was washed with water. The combined filtrate was subjected to lyophilization to afford 234 mg. of a crude N-acetyl derivative. Its infrared spectrum showed strong absorptions at 1740 cm-1 characteristic of oxamic acid group. The N-acetyl derivative (178 mg.) was treated with 40 ml. 

Thiazolo[2,3-c][l,2,4]triazines 658 were prepared (84LA1302) regio-specifically by cyclizing 2-hydrazono-2-thiazoline 659 with glyoxylic acid or ester. They had herbicidal activity. Condensation of 659 with oxamic acid ethyl ester gave hydrazide 660, which was cyclized with sodium... 

Oxamic Acid Azide (Azido Oxamate, Oxamido-azide, Oxamidsaureazid or Oxalsaure-amid-azid in Ger). H2N.CO.CO.N3, mw 114.02, N 49.11%, OB to C02 —42.09%, crystals from acet+petr eth mp, explds violently ca 115° or on rubbing. Can be prepd by treating the hydrazide of oxamic acid with Na nitrite in w Refs 1) Beil 2, (244) 2) T. Curtius, JPraktChem [2] 91, 426 (1915) 3) Urbanski 3... 

CnHijNjO, 80573-04-2) see Balsalazide sodium DL-(l-carboxyethyl)oxamic acid diethyl ester (C7H15NO5 23460-73-3) see Pyridoxine... 

A/-Ethoxymethyl-A/-(2-ethyl-6-methylphenyl) oxamic acid, sodium salt... 

Oxamic acid 26 and AT-hydroxyoxamic acid 27 derivatives were disclosed by the Boehringer Ingelheim group as moderately active Lck SH2 domain antagonists [119,130]. 

Cross double carbonylation of amines and alcohols Oxamates can be prepared by double carbonylation of amines and alcohols in the presence of (CH,CN)2PdCl2 as catalyst with 02 and Cul as oxidant and co-catalyst. This reaction is particularly efficient when applied to (3-amino alcohols. 

The direct conversion of alcohols and amines into carbamate esters by oxidative carbonylation is also an attractive process from an industrial point of view, since carbamates are useful intermediates for the production of polyurethanes. Many efforts have, therefore, been devoted to the development of efficient catalysts able to operate under relatively mild conditions. The reaction, when applied to amino alcohols, allows a convenient synthesis of cyclic urethanes. Several transition metal complexes, based on Pd [218— 239], Cu [240-242], Au [243,244], Os [245], Rh [237,238,246,247], Co [248], Mn [249], Ru [224,250-252], Pt [238] are able to promote the process. The formation of ureas, oxamates, or oxamides as byproducts can in some cases lower the selectivity towards carbamates. 

Under appropriate conditions, alcohols and amines can undergo an oxidative double carbonylation process, with formation of oxalate esters (Eq. 34), oxamate esters (Eq. 35) or oxamides (Eq. 36). These reactions are usually catalyzed by Pd(II) species and take place trough the intermediate formation of bis(alkoxycarbonyl)palladium, (alkoxycarbonyl)(carbamoyl)palladium or bis(carbamoyl)palladium complexes, as shown in Scheme 29 (NuH, Nu H = alcohol or amine) [227,231,267,293-300]. 

The analogue, t-butyl methyl iminodicarboxylate 25, is obtained by the reaction of methanol with t-butyl oxamate (24) in the presence of lead tetraacetate. Its stable non-hygroscopic potassium salt is converted into alkyl derivatives 26 by the action of alkyl halides such as butyl bromide, allyl bromide, propargyl bromide and ethyl bromoacetate. The products are hydrolysed by trifluoroacetic acid to salts of primary amines, whereas... 

Fig. 11.7. The two pathways of dechlorination of chloramphenicol (11.39). Cytochrome P450 catalyzed oxidation to yield the oxamic acid derivative (11.40), and hydrolytic dechlorination to yield both oxamic acid (11.40) and primary alcohol (11.41) metabolites [75].

In contrast to oxidative dechlorination, the hydrolytic dechlorination of chloramphenicol replaces a Cl-atom with a OH group to yield a (monochlo-ro)hydroxyacetamido intermediate. The latter, like the dichloro analogue, also eliminates HC1, but the product is an aldehyde that is far less reactive than the oxamoyl chloride intermediate. Chloramphenicol-aldehyde undergoes the usual biotransformation of aldehydes, namely reduction to the primary alcohol 11.41 and dehydrogenation to the oxamic acid derivative 11.40 (Fig. 11.7). 

In conclusion, the oxamic acid derivative is produced by two distinct metabolic pathways, namely by oxidative and hydrolytic dechlorinations. In contrast, the primary alcohol metabolite 11.41 can be produced only by hydrolytic dechlorination and is, thus, an unambiguous marker of this pathway. The alcohol 11.41 is a known urinary metabolite of chloramphenicol in humans. 

The oxamate group has been incorporated into a vinyl polymer by Kirsh and Kabanov 41). These workers prepared a copolymer of 4-vinyl-A -(phenacyloxime)pyridinium bromide and vinylpyridine. For the hydrolysis of p-nitrophenyl acetate the oxamate polymer produced a significant rate enhancement over the monomeric analogs. 

A number of published papers have included SAR details for several series of compounds, including the phenoxazines (89) [485], naphthoylvalerohydr-oxamic acids represented by (115) [486] and the ICI series represented by (145) and (146) [487]. A full paper dealing with the 4-hydroxythiazoles represented by (74) indicated that only compounds existing in the enolic form were active 5-unsubstituted cases and also 5,5-disubstituted cases (which are ketonic) were inactive [488]. Acylation of the hydroxyl was acceptable for good activity. No strong correlation of aryl substitution with potency... 

Synonyms AI3-16398 BRN 3910347 trans-Ch oxAm /7a/ 5-y-Chlordane P-Chlordane y-Chlordane EINECS 225-826-0 l,2,4,5,6,7,8,8-Octachloro-3a,4,7,7a-tetrahydro-4,7-methanoin-dan RCRA waste number U036 UN 2762. 

Chemical/Physical. The gas-phase reaction of ozone with pyridine in synthetic air at 23 °C yielded a nitrated salt having the formula [CeHsNHJ NOs (Atkinson et al., 1987). Ozonation of pyridine in aqueous solutions at 25 °C was studied with and without the addition of ferf-butyl alcohol (20 mM) as a radical scavenger. With tert-hniyX alcohol, ozonation of pyridine yielded mainly pyridine W-oxide (80% yield), which was very stable towards ozone. Without terf-butyl alcohol, the heterocyclic ring is rapidly cleaved forming ammonia, nitrate, and the amidic compound W-formyl oxamic acid (Andreozzi et al., 1991). 

Oxadiazonphenol, see Oxadiazon Oxalic acid, see Acetic acid, 2-Chlorophenol, Cyclohexene, 2,4-D, 2,4-Dinitrophenol, 1,4-Dioxane, Glycine. 2-Methylphenol, Naphthalene, 4-Nitroaniline, 4-Nitrophenol, Parathion, Phenol, Picloram. 2,4,5-T Oxamic acid, see Acetamide 1 -Oxa-2-oxocycloheptane, see Cyclohexane Oxindole, see Indole... 

CoHijCbNOs 2-(2,4-Dichlorophenoxy)-A -(4- metiiylplienyl)acetohyoxamic acid Extraction-photometric V 3... 

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