Synthesis and properties of analogs of pyridoxal

A method for the synthesis of analogs of pyridoxal-2-norpyridoxal, 6-methyl-2, 4-pyridoxal, and 6-methylpyridoxal—has been worked out. The reaction of 5-ethoxyoxazoles with maleic diesters gave diesters of substituted 3-hydroxycinchomeric acids, which were converted by reduction with lithium aluminum hydride into analogs of pyridoxine. The latter were oxidized with magnesium dioxide to the corresponding analogs of pyridoxal. The oximes of the aldehydes and their Schiff's bases with p-phenetidine have been obtained. Analogs of pyridoxamine have been obtained by the hydrogenation of the oximes. The UV absorption spectra of the compounds and the ratios of the ionic forms in aqueous solutions have been studied.     

Synthesis and properties of analogs of pyridoxal

A method for the synthesis of analogs of pyridoxal-2-norpyridoxal, 6-methyl-2, 4-pyridoxal, and 6-methylpyridoxal—has been worked out. The reaction of 5-ethoxyoxazoles with maleic diesters gave diesters of substituted 3-hydroxycinchomeric acids, which were converted by reduction with lithium aluminum hydride into analogs of pyridoxine. The latter were oxidized with magnesium dioxide to the corresponding analogs of pyridoxal. The oximes of the aldehydes and their Schiff's bases with p-phenetidine have been obtained. Analogs of pyridoxamine have been obtained by the hydrogenation of the oximes. The UV absorption spectra of the compounds and the ratios of the ionic forms in aqueous solutions have been studied.     

超声辐射下水溶液中芳醛肟的合成

在没有催化剂条件下, 芳香醛与盐酸羟胺的水溶液经超声辐射于室温反应, 可以72%～98%收率得到肟. 该方法具有操作简便、反应条件温和、反应时间短、对环境友好等优点.     

Preparation of 3-Aryl-4-(5-ARYL-Δ2-1,2,4-Oxadiazolin-3-YL)Sydnones and their Conversion into 3-ARYL-4-(5-ARYL-1,2,4-Oxadiazol-3-YL)Sydnones

3-Aryl-4-(5-aryl-Δ²-1,2,4-oxadiazolin-3-yl)sydnones (5) were synthesized in high yields by the reaction of 3-arylsydnone-4-carboxamide oximes (prepared from the corresponding 3-arylsydnone-4-carbonitriles) with aromatic aldehydes in the presence of acid catalysts. No reaction occurred when aliphatic aldehydes were used. The oxadiazolin-3-ylsydnones (5) were easily converted into the corresponding 3-aryl-4-(5-aryl-1,2,4-oxadiazol-3-yl)sydnones by N-bromosuccinimide oxidation. The 3-arylsydnone-4-carbonitrile oxides were synthesized in good yields by N-bromosuccinimide oxidation of the corresponding 3-arylsydnone-4-carboxaldehyde oximes.     

Development of a multiresidue method for analyzing herbicide and fungicide residues in bovine milk based on solid-phase extraction and liquid chromatography-tandem mass spectrometry

The adverse effect of reactive chemical residues on the quality of drug products has necessitated the determination of low-molecular-weight aldehydes in pharmaceutical excipients. An analytical methodology for the detection of trace amounts of C1-C8 aliphatic aldehydes and benzaldehyde in excipients is described. The proposed procedure is based on the derivatization of aldehydes in aqueous solution with O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA), followed by static headspace gas chromatographic (SHS-GC) analysis of PFBHA aldehyde oximes with negative chemical ionization (NCI) MS detection. The method developed was demonstrated to be simple, selective, sensitive, and was successfully applied to the screening of aldehydes at sub-microg/g levels in over 30 typical excipients. The most abundant aldehydes found in the samples were formaldehyde and acetaldehyde, for which a rapid and reliable routine quantification method by readily available SHS-GC instrumentation coupled with flame-ionization detection was also developed and validated.     

Synthesis of 2-aryl(hetaryl)-1-hydroxyimidazoles by the reaction of aliphatic 1,2-hydroxylamino oximes with aromatic and heteroaromatic aldehydes

A reaction of aliphatic 1,2-hydroxylamino oximes bearing the hydroxylamino group at the secondary carbon atom with aromatic and heteroaromatic aldehydes in acetic acid leads to the corresponding 1-hydroxy-2-aryl(hetaryl)-4,5-dialkylimidazoles in high yields. α-Aryl(hetaryl)-nitrones initially formed by the condensation of 1,2-hydroxylamino oximes with aldehydes are quantitatively converted to the corresponding imidazoles.     

The Synthesis and Reactions of N-Hydroxy-3-Arylsydnone-4-Carboxamide Oximes

N-Hydroxy-3-arylsydnone-4-carboxamide oximes (7) were prepared from the corresponding 3-arylsydnone-4-carbohydroximic acid chlorides (6) and hydroxylamine in high yield. The chemical reactivity of compound (2) is somewhat different from 3-arylsydnone-4-carboxamide oximes (2) in that the former compounds reacted with both aromatic and aliphatic aldehydes in the presence of acid catalyst to give 3-aryl-4-(5-aryl-1,2,4-oxadiazol-3-yl)sydnones (5) and 3-aryl-4-(5-alkyl-1,2,4-oxadiazol-3-yl)sydnones (3).     

Regioisomeric oximes and thiosemicarbazones derived from 6-substituted pyridoxines

The selective oxidation of 2- and 4-positioned hydroxymethyl groups of 6-methyl-2,3,4-tris(hydroxymethyl)pyridin-5-ol was developed and the thus obtained aldehydes were converted into their oximes and thiosemicarbazones.     

Transformation of Oximes and Alcohols to Carbonyl Compounds Using Amberlite IRA-400 Supported Chromic Acid in the Presence of Zirconium Tetrachloride

A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method. A wide variety of oximes and alcohols were efficiently converted to their corresponding aldehydes and ketones in good to excellent yields using amberlite IRA-400 supported chromic acid in the presence of zirconium tetrachloride in refluxing acetonitrile-H2O. Selective oxidation of oximes and alcohols in the presence of other functional groups such as acetal, hydrazone, aldehyde, ether and alkene can be considered as a noteworthy advantage of this method.     

A NEW APPLICATION OF N-BROMOSACCHARIN AS A SELECTIVE AND EFFICIENT OXIDATIVE REAGENT FOR REGENERATION OF CARBONYL COMPOUNDS FROM OXIMES

A new method for the direct conversion of various oximes into aldehydes and ketones by treatment with N-bromosaccharin is described. N-bromosaccharin can be used for an effective, selective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield.     

Synthesis of sterically hindered ketones from aldehydes via O-silyl oximes

A mild and efficient method to synthesize sterically hindered ketones from aldehydes via O-silyl oximes was developed. Treatment of O-triphenylsilylated oximes with alkyl iodides in the presence of triethyl borane afforded the corresponding ketones.     

Transition metal complexes with Schiff-base ligands: 4-aminoantipyrine based derivatives–a review

The survey highlights structural properties and biological studies of transition metal complexes derived from 4-aminoantipyrine. The most important results of extensive studies (syntheses, spectral, magnetic, redox, structural characteristics, antimicrobial and DNA cleavage) of the metal complexes with heterocyclic Schiff bases of 4-aminoantipyrine with some aldehydes and oximes are reviewed.     

Conversion of oximes to carbonyl compounds by triscetylpyridinium tetrakis(oxodiperoxotungsto) phosphate (PCWP)-mediated oxidation with hydrogen peroxide

Aromatic and aliphatic oximes have been deoximated in chloroform-water to the corresponding aldehydes with dilute hydrogen peroxide and triscetylpyridinium tetrakis (oxodiperoxotungsto) phosphate as catalyst. The presence of dipolarophiles in the reaction mixtures allows a competitive reaction that converts oximes into isoxazole and isoxazoline derivatives via the intermediate formation of nitrile oxide species.     

Regeneration of Aldehydes and Ketones from Oximes Using Bis(Trimethylsilyl)Chromate

Bis(trimethylsilyl) chromate transforms oximes of not only ketones but also aldehydes and 1,2-diketones to the corresponding carbonyl compounds, in high yields.     

Synthesis of 4,5-Dialkyl-2-perfluoroaryl-1H-imidazol-1-ols and 4,5-Dimethyl-2-perfluoroaryl-1H-imidazoles

Russian Journal of Organic Chemistry - Aliphatic α-hydroxyamino oximes reacted with perfluoroaromatic aldehydes to give α-perfluoroaryl nitrones which underwent cyclization in acetic acid...     

Synthesis of isomeric 4- and 5-hydroxylaminothiazolidin-2-thiones

Tsomeric 4- and 5-hydroxylaminothiazolidin-2-thiones were synthesized by the reaction of 1,2-aminosubstituted oximes with CS₂, and of dimeric olefin nitrosochlorides with dithiocarbamate salts. These compounds react with aldehydes and ketones to form the respective nitrones. In contrast to the 5-derivatives, the 4-hydroxylamino derivatives hydrolyze to 4-hydorxythiazolidin-2-thiones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 549–553, April, 1986.     

Preparative conversion of oximes to parent carbonyl compounds by cerium(IV) sulfate in acetonitrile and alcohol

A new method for the direct conversion of oximes into aldehydes and ketones by treatment with cerium(IV) salts is described. Cerium(IV) salts can be used as an effective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield. The solvent effects are discussed. Copyright © 1999 John Wiley & Sons, Ltd.     

A Mild Oxidant for the Regeneration of Carbonyl Compounds from Oximes in Nonaqueous Condition

Since oximes have been empolyed as ketone or aldehyde functional group equivalents in synthetic organic chemistry, the conversion of oximes into their corresponding carbonyl compounds has received considerable attention. The classical method for the cleavage of oximes to parent aldehydes and ketones is hydrolysis in acid, which is not suitable for acid sensitive compounds1-2. In recent years, cleavage of oximes with ozone3, nitrogen tetraoxide4, copper chloride5 and bromine6 have been develope…     

Regeneration of aldehydes and ketones by the oxidation of oximes using potassium permanganate-graphite with grinding under solvent-free conditions

Russian Journal of Applied Chemistry - A facile and efficient procedure for the oxidative cleavage of oximes to their parent aldehydes and ketones by grinding with potassium permanganate-graphite...     

Carbonyl Regeneration from Oximes and Semicarbazones by Trimethylchlorosilane-Dimethylsulphoxide

Treatment of oximes and semicarbazones of saturated and α,β-unsaturated ketones and aldehydes with trimethylchlorosilane-dimethyl sulphoxide in dry acetonitrile affords the corresponding carbonyl compounds in excellent yields under mild conditions.