Hydroxy acetaldehyde

In E. coli GTP cyclohydrolase catalyzes the conversion of GTP (33) into 7,8-dihydroneoptetin triphosphate (34) via a three-step sequence. Hydrolysis of the triphosphate group of (34) is achieved by a nonspecific pyrophosphatase to afford dihydroneopterin (35) (65). The free alcohol (36) is obtained by the removal of residual phosphate by an unknown phosphomonoesterase. The dihydroneoptetin undergoes a retro-aldol reaction with the elimination of a hydroxy acetaldehyde moiety. Addition of a pyrophosphate group affords hydroxymethyl-7,8-dihydroptetin pyrophosphate (37). Dihydropteroate synthase catalyzes the condensation of hydroxymethyl-7,8-dihydropteroate pyrophosphate with PABA to furnish 7,8-dihydropteroate (38). Finally, L-glutamic acid is condensed with 7,8-dihydropteroate in the presence of dihydrofolate synthetase. 

Ethoxycarbonyloctyl 2-acetamido-2-deoxyglucopyranoside, E-22 8-Ethoxycarbonyloctyl hepta-O-acetyl-a-D-cellobiopyranoside, C-25 8-Ethoxycarbonyloctyl hepta-0-acetyl-p-D-cellobiopyranoside, C-25 8-Ethoxycarbonyloctyl hepta-O-acetyl-p-D-lactopyranoside, C-25 8-Ethoxycarbonyloctyl hepta-O-acetyl-a-D-maltopyranoside, C-25 8-Ethoxycarbonyloctyl hepta-O-acetyl-p-D-maltopyranoside, C-25 2-E t hoxy- 2- hydroxy acetaldehyde, G-558... 

Hydropiperoside, S-92 Hydrosin, D-681 Hydroxalic acid, G-241 Hydroxy acetaldehyde, H-131... 

Costa suggested a non-ionic mechanism for the hydroformyiation of formaldehyde starting with neutral hydrido metal carbonyls (Scheme 6.124) [29]. In the last step, the hydrogenation of hydroxy acetaldehyde group takes place, which affords finally ethylene glycol. 

Acetaldehyde (and other aldehydes containing at least one hydrogen atom in the a position) when treated with a small quantity of dilute sodium hydr oxide solution or other basic catalyst gives a good yield of aldol (p hydroxy-n-but3Taldehyde) (I), which readily loses water, either by heating the isolated aldol alone or with a trace of mineral acid, to form crotonaldehyde (II) ... 

Thus the condensation of dichloroether or chloroacetone fails to give the parent compound, 2-hydroxythiazole (158a), Rj = R2 = R3 = H (221). However, 2-hydroxythiazole can be obtained in 12% yield from chloro-acetaldehyde (386). The condensation of ammonium thiocarbamate with cf-chloroketones gives the corresponding 2-hydroxy derivatives in 25 to 70% yields (76, 221, 304, 412) (Table 11-24). These compounds condensed with ClP(S)(OEt)2 give the corresponding 2-thiazolyl-thiophosphates (791). 

Hydroxy 2 methylbutanal (from addition of enolate of propanal to acetaldehyde)... 

Formaldehyde condenses with itself in an aldol-type reaction to yield lower hydroxy aldehydes, hydroxy ketones, and other hydroxy compounds the reaction is autocatalytic and is favored by alkaline conditions. Condensation with various compounds gives methylol (—CH2OH) and methylene (=CH2) derivatives. The former are usually produced under alkaline or neutral conditions, the latter under acidic conditions or in the vapor phase. In the presence of alkahes, aldehydes and ketones containing a-hydrogen atoms undergo aldol reactions with formaldehyde to form mono- and polymethylol derivatives. Acetaldehyde and 4 moles of formaldehyde give pentaerythritol (PE) ... 

In this thiamine pyrophosphate-mediated process, ben2aldehyde (29), added to fermenting yeast, reacts with acetaldehyde (qv) (30), generated from glucose by the biocatalyst, to yield (R)-l-phen5l-l-hydroxy-2-propanone (31). The en2ymatically induced chiral center of (31) helps in the asymmetric reductive (chemical) condensation with methylamine to yield (lR,23)-ephedrine [299-42-3] (32). Substituted ben2aldehyde derivatives react in the same manner (80). 

Most diaziridines are not sensitive towards alkali. As an exception, diaziridines derived from 2-hydroxyketones are quickly decomposed by heating with aqueous alkali. Acetaldehyde, acetic acid and ammonia are formed from (162). This reaction is not a simple N—N cleavage effected intramolecularly by a deprotonated hydroxy group, since highly purified hydroxydiaziridine (162) is quite stable towards alkali. Addition of small amounts of hydroxybutanone results in fast decomposition. An assumed reaction path — Grob fragmentation of a hydroxyketone-diaziridine adduct (163) — is in accord with these observations (B-67MI50800). 

Cyclopropyl-3-fluoro-2-hydroxy-6-oxo-6//-pyrido[l,2-n]pyrimidine-7-carboxylates 340 were obtained in the reaction of 2-cyclopropyl-2-(5-fluoro-4-hydroxy-2-pyrimidinyl)acetaldehyde (339) and ethyl, rerr-butyl and dibenzyl malonates in the presence of piperidine and AcOH (95MIP1, 96JMC3070, 96MIP4, 96USP5580872). 

Q -Hydroxy-3Q (tetrahydropyran-2-yloxy)-2/3-(3Q -tetrahydropyran-2-yloxy-4-phenoxy-trans-1-buten-1 -yl)cyclopent-1Q -yl] -acetaldehyde a-hemiacetal Chromic anhydride Methanesulfonyl isocyanate Acetic acid... 

The fourth and last fundamental reaction of carbonyl groups, carbonyl condensation, lakes place when two carbonyl compounds react with each other. When acetaldehyde is treated with base, for instance, two molecules combine to yield the hydroxy aldehyde product known as aldol aidehyde + alcoho/) ... 

A carbonyl condensation reaction between two molecules of acetaldehyde yields a hydroxy aldehyde product. 

In general, pyruvate decarboxylase (EC 4.1.1.1) catalyzes the decarboxylation of a 2-oxocar-boxylic acid to give the corresponding aldehyde6. Using pyruvic acid, the intermediately formed enzyme-substrate complex can add an acetyl unit to acetaldehyde already present in the reaction mixture, to give optically active acetoin (l-hydroxy-2-butanone)4 26. Although the formation of... 

Besitzen Aldehyd und Keton a-H-Atome, so werden diese zunachst durch Hydroxy-methyl-Gruppen ersetzt. Auf diese Weise erhalt man z. B. aus Acetaldehyd und vier Molen Formaldehyd Pentaerythrit (73% d.Th.)4 bzw. aus Cyclohexanon mit fiinf Molen Formaldehyd 2-Hydroxy-1,1,3,3-tetrakis-[hydroxymethyl]-cyclohexan (73-85% d.Th.). Da es sich hierbei zunachst um eine Aufbaureaktion handelt, wird diese Umsetzung in Bd. VI/la/2, S. 1314f. geschlossen abgehandelt (vgl. auch Lit.s). 

The metabolism of NMOR in the rat is outlined in Figure 4. o-Hydroxylation yields the unstable intermediates and the latter hydrolyzes to (2-hydroxyethoxy)acetaldehyde [7] which has been identified as a liver microsomal metabolite by isolation of the corresponding 2,4-dinitrophenylhydrazone (59). (2-Hydroxy-ethoxy)acetaldehyde, which exists predominantly as the cyclic hemiacetal was not detected in the urine of rats gavaged with 125 mg/kg NMOR. However, (2-hydroxyethoxy)acetic acid was a major urinary metabolite (16% of the dose). These transformations are analogous to those observed with NPYR and NNN. 

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