Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Carboxylic acids glyoxylic

In the laboratory of A. Golebiowski, the high throughput synthesis of diketopiperazines was accomplished. These compounds can serve as 3-turn mimetics. The key step in this approach was a Petasis boronic acld-Mannich reaction between the Merrifield resin-bound piperazine-2-carboxylic acid, glyoxylic acid, and a wide range of commercially available boronic acids to provide a 1 1 mixture of the products. A specific example is shown below. [Pg.341]

Aliphatic carboxylic acids are difficult to reduce electroehemically. Reduction of a 10% oxalic acid in 10% H2SO4. at 15 °C at a mercury cathode (Refs. [494, 532] in Ref. [29]), a lead or amalgamated lead cathode (Ref. [495] in Ref. [29]) or at a sodium amalgam (Na(Hg) cathode (Ref. [497] in Ref. [29]) produces glyoxylic acid with a material yield of 88% and a current efficiency of 70%. The glyoxylic acid formed is stabilized by hydration [29]. [Pg.151]

In the reactions of 4-amino-l-azadienes 295 with esters of glyoxylic acid, chemoselective cyclization occurred with displacement of the amino group NHR, and 2/7-1,3-oxazine-2-carboxylic acid derivatives 296 were formed in high yields instead of the corresponding 1,2-dihydropyrimidines usually obtained in the reactions of 295 with aliphatic or aromatic aldehydes (Equation 28) <1996T3095>. [Pg.413]

Almotriptan has also been synthesized via decarboxylation of the carboxylic acid intermediate 65, but a detailed preparation of 65 was not provided in the patent literature (Scheme 22)." The patent indicates that the carboxy indole 65 was prepared according to the method of Gonzalez.°° Thus, (2-oxo-tetrahydro-3-furanyl)-glyoxylic acid ethyl ester (62) was heated in aqueous H2SO4 to give 2-oxo-5-hydroxypentanoic acid in situ, which was treated with hydrazine 59 to produce hydrazone 63. Fischer cyclization of 63 using HCl gas in DMF gave the lactone 64, which was converted to carboxylic acid 65. Decarboxylation of 65 was catalyzed by cuprous oxide in quinoline at 190 °C to afford almotriptan (5)." ... [Pg.178]

Access to racemic thiazolidine-2-carboxylic acid (3-thiaproline, 12) is obtained by reacting cysteamine (49) with glyoxylic acid ester (Scheme 9), 165>182>1831 whilst the reaction of (R)-cysteine with glyoxylic acid 184 1851 leads to (2/ /S,5/ )-thiazolidine-2-carboxylic acid. 185 The diastereomers of thiazolidine-2-carboxylic add (12) are rapidly interconverting and therefore cannot be separated. 185 In the presence of (2R,3R)- and (2S,3S)-tartaric acid, reaction of cysteamine with glyoxylic acid leads to the enantiomerically pure (2/ )- and (2S)-thia-zolidine-2-carboxylic acid salts. 186 The acids undergo fast racemization in acetic acid. 186 ... [Pg.74]

Since aldehydes can generally be converted to the corresponding carboxylic acids in very good yields and in a simple manner by catalytic air oxidation, electrochemical syntheses are not of much interest to the chemical industry. The controlled electrochemical oxidation of glyoxal to glyoxylic acid is an exception 279 280> ... [Pg.31]

Industrial work on the reduction of carboxylic acids was focused on the search for an electrochemical synthesis of glyoxylic add from oxalic acid ... [Pg.62]

In a critical study of the periodate oxidation of raffinose and related oligosaccharides, Courtois and Wickstrom showed78 that 1 mole of raffinose reduces 5 moles of periodate, with the formation of 2 moles of formic acid plus a hexaldehyde. Conversion of the aldehyde to the hexa-carboxylic acid, followed by hydrolysis, gave the expected amounts of glyoxylic acid, glyceric acid, hydroxypyruvic acid, and glycolaldehyde (by decarboxylation of hydroxypyruvic acid). [Pg.168]

Table 2.12 ont/ -Mannich-type reactions of aldehyde donors and N-PMP-protected glyoxylate imine catalyzed by (3/ ,5/ )-5-methyl-3-pyrrolidine-carboxylic acid (13) [73]. [Pg.41]

Selenazolidine-2-carboxylic acid (95) is prepared by reduction of selenocysteamine and subsequent treatment with sodium glyoxylate (Scheme 38) (79MI42000). ( )-Selenazolidine-4-carboxylic acid (96) is synthesized in good yield by cyclic condensation of DL-selenocysteine with formaldehyde (Scheme 39) (77MI42000). [Pg.346]

The synthesis and characterization of a new 6-phosphoverdazyl radical incorporated into a spirocyclic framework containing a cyclotriphosphazane ring has been reported <02CJC1501>. Verdazyl-3-carboxylic acid (35) was prepared by condensation of carbonic acid bis(l-methylhydrazide) (33) with glyoxylic acid, to give tetrazine (34), and subsequent oxidation with benzoquinone. The coordination chemistry of this water-soluble verdazyl derivative was explored <02CC1688>. [Pg.345]

Glyoxylic acid (= Oxoacetic acid) (carboxylic acid) Universal unripe fruit, young leaf Beta vulgaris (young sugar beet) (Chenopodiaceae), Ribes uva-crispa (Grossulariaceae) [fruit] Sour (acid) taste [irritant]... [Pg.416]

Werber and Maggio have shown that electron-donating substituents in position 2 can increase the stability of 1,3,4-thiadiazole carboxylic acids. They oxidized ethyl and butyl glyoxylate thiosemi-carbazones (27) with ferric chloride and obtained ethyl (butyl)... [Pg.173]

The absolute configuration of samandaridine was determined by partial synthesis (11). Condensation of iV-acetylsamandarone (XVIII) with glyoxylic acid yields a mixture of the two carboxylic acids XIX and XX. Reduction of the former, first with sodium borohydride and then catalytically generates samandaric acid (XXI), which on boiling with dilute mineral acid lactonizes to samandaridine (XVII). [Pg.433]

The glyoxylate-ene reaction, promoted by the Ti-BINOL complex, produces chiral a-hydroxy esters, which provide an easy access to the corresponding carboxylic acid derivatives bearing a chiral center at the a position. The adduct between the glyoxylate and exo olefin is proposed as a key intermediate of the collagenase-selective inhibitor, Trocade (Hoffmann-La Roche) [20]. This remarkable process has been developed for large-scale production. [Pg.574]

Depending on the reaction conditions, a-iminodicarboxylic acid derivatives or 2,6-di-piperazinediones [120] are formed from a-amino acids, oxocompounds and isocyanides. The isomeric 2,4-piperazinediones can thus also be formed by some of the U-4CR of vicinal diamines, isocyanides, oxocompounds and glyoxylic monoesters [121,122],The libraries of highly substituted 2-piperazones were produced by the chemists of Merck Inc. from N-monosubstituted ethylenediamines, carboxylic acids, isocyanides and chloroacetalde-hyde. [Pg.156]


See other pages where Carboxylic acids glyoxylic is mentioned: [Pg.46]    [Pg.310]    [Pg.160]    [Pg.270]    [Pg.170]    [Pg.116]    [Pg.44]    [Pg.464]    [Pg.152]    [Pg.61]    [Pg.475]    [Pg.289]    [Pg.438]    [Pg.151]    [Pg.129]    [Pg.158]    [Pg.55]    [Pg.227]    [Pg.289]    [Pg.438]    [Pg.155]    [Pg.110]    [Pg.524]    [Pg.475]    [Pg.134]    [Pg.159]    [Pg.270]    [Pg.266]    [Pg.137]    [Pg.105]    [Pg.269]   
See also in sourсe #XX -- [ Pg.376 ]




SEARCH



Glyoxylate

Glyoxylic acid acids

© 2024 chempedia.info