An efficient method for the oxathioacetalization of carbonyl compounds using N-bromosaccharin as a catalyst

A mild and highly chemoselective method for the preparation of oxathiolane from aliphatic and aromatic aldehydes and ketones with 2-mercaptoethanol in the presence of catalytic amount of N-bromosaccharin at room temperature is reported.     

Titrimetric methods for the determination of vitamin C in some pharmaceutical preparations by use of two N-bromoimides

Potentiometric and visual end-point titrations with N-bromophthalimide and N-bromosaccharin are proposed for the determination of vitamin C in various pharmaceutical preparations. These methods are simpler than the existing methods for the purpose.     

Determination of some sulphur compounds with N-bromoimides

Two stable oxidants, N-bromophthalimide and N-bromosaccharin are proposed as reagents for the visual and potentiometric titrimetric of thioureas, isothiocyanates, xanthates, dithiocarbamates, thiols, sulphur, thiosulphate, thiocyanate and thiocarbonate. The results are precise within 0.1-0.3%.     

Determination of some carbohydrates with N-bromophthalimide and N-bromosaccharin

Two better titrimetric methods have been developed for determination of carbohydrates such as glucose, fructose, lactose and sucrose, and sugars present in honey and milk. They involve reduction of Cu(II) to Cu(I) by the carbohydrate concerned, and oxidative titration of the Cu(I) with a standard solution of N-bromophthalimide or N-bromosaccharin.     

A CONVENIENT ONE-POT METHOD OF CONVERTING ALCOHOLS INTO OXIMES

The one-pot conversion of[3pc] primary and secondary alcohols into oximes is reported using chromium trioxide supported on alumina and hydroxylamine hydrochloride under solvent free condition. This oxidation-oxime formation reaction has been applied to a range of aliphatic and benzylic alcohols.     

A VERSATILE METHOD FOR THE CONVERSION OF ALDOXIMES TO NITRILES USING SILICA GEL/THIONYL CHLORIDE

A simple convenient procedure for dehydration of aldoximes has been developed using silica gel/thionyl chloride in heterogeneous conditions. The method has been found to be effective for a wide range of aromatic oximes.     

N-BROMOBIS(P-TOLUENESULFONYL)AMINE AS A NOVEL AND MILD REAGENT FOR CONVERSION OF OXIMES TO CARBONYL COMPOUND

N-Bromobis(p-toluenesulfonyl)amine (NBBTA) is a novel and efficient reagent for the conversion of oximes to their corresponding carbonyl compounds in good yields under mild conditions.     

TRIMETHYLAMMONIUM CHLOROCHROMATE ADSORBED ON ALUMINA AS A NEW REAGENT FOR THE CLEAVAGE OF OXIMES AND P-NITROPHENYLHYDRAZONES

Derivatives of carbonyl compounds such as oximes and p-nitrophenylhydrazones have played an important role in the protection of carbonyl compounds,as they are highly crystalline and stable compounds. They are also very extensively used for the characterization and purification of carbonyl compounds. Regeneration of carbonyl compounds from their derivatives under mild condition is an important process in synthetic organic chemistry.     

Analysis of oxosteroids by nano-electrospray mass spectrometry of their oximes

A method for the analysis of neutral oxosteroids by electrospray mass spectrometry is described. The oxosteroids are converted into their oximes by treatment with hydroxyammonium chloride in aqueous methanol. Intense peaks corresponding to protonated oxime molecules are observed in nano-electrospray mass spectra. The detection limits for the oximes of progesterone, pregnenolone and dehydroepiandrosterone were 2.5, 5 and 25 pg/microL, respectively, approximately 20 times lower than for the underivatised steroids. The signal intensities were proportional to the concentration of the steroids in the range of 500 to 2.5 pg/microL. Fragmentation by collision-induced dissociation (CID) was studied using oximes of 28 model steroids carrying an oxo group at C-3, C-17 or C-20. Some of the steroid oximes were labelled with deuterium or (15)N. Fragment ions were observed which yielded useful structural information. Upon CID, protonated oximes of 3-oxo-Delta(4)-steroids produced abundant ions by cleavage through the B-ring and by loss of the side chain, while protonated oximes of saturated 3-oxosteroids did not give abundant ions by cleavage through the B-ring. Protonated oximes of 20-oxosteroids unsubstituted at C-21, C-17 or C-16 produced a characteristic ion at m/z 86 containing the side chain, C-16 and C-17. Protonated oximes of steroids containing only a 17-oxo group gave fewer ions of diagnostic value. Coupled with the selective isolation of steroid oximes from a biological matrix this method of derivatisation and CID may be used for the analysis of neutral oxosteroids in biological samples.     

取代查耳酮肟电化学氧化机理的研究

研究了７种取代查耳酮肟的电化学行为。用氢氧化钠底液热解石墨工作电极，取代查耳酮肟的电极过程为１ｅ氧化不可逆吸附电极过程。它们的氧化电位随取代基吸电子能力的增强而增高，并与它们相应的Ｈａｍｍｅｔｔ常数呈线性关系。取代查耳酮肟的电化学氧化机理为先失去一个电子生成ｉｍｉｎｏｘｙ自由基，然后由基对分子内烯键进行环化加成，脱氢后形成３，５－二聚代异恶唑。用控电位电解和紫外吸收光谱检测了部份电化学氧化产物，证     

Studies in pyran,its analogs,and related compounds

The lithium aluminum hydride reduction of the ethers and tosylates of chroman-4-one oxime and related compounds has been studied. It has been found that the ethers of the oximes, like the oximes, do not undergo a normal, but rather an anomalous, reduction. The tosylates of the oximes exhibit a higher tendency to undergo anomalous reduction than the corresponding oximes. During the synthesis of the ethers of the oximes it was established that the use of dimethylformamide as the medium for alkylation of the oxime salts helps to suppress the side reaction forming nitrones.For part XXXVII, see [23].     

A novel and efficient catalytic system including TEMPO/acetaldoxime/InCl3 for aerobic oxidation of primary amines to oximes

A simple and efficient catalytic system including TEMPO/acetaldoxime/InCl₃ for aerobic oxidation of primary amines to corresponding oximes by using toluene as the solvent is described. This practical method can use O₂ as the economic and green oxidant, tolerate a wide range of substrates, which can afford the target oximes in moderate to excellent yields.     

Reactions of 1,2,4-triazines with nitromethide ion. A convenient method of preparation of 1,2,4-triazin-5-ylcarbaldehyde oximes and their synthetic applications

An efficient procedure for the preparation of 1,2,4-triazin-5-ylcarbaldehyde oximes 2a-f from 1,2,4-triazines 1a-f and nitromethide ion is described. The oximes 2c-d were converted into corresponding 5-cyano-1,2,4-triazines 6c-d . The latter compounds react easily with various nucleophiles to afford 5-substituted 1,2,4-triazines 7a-i and with 1-pyrrolidino-1-cyclohexene to form cyano derivative of 5,6,7,8-tetrahydroisoquinoline 9 .     

N-Methylpiperidinium Chlorochromate Adsorbed on Alumina: A New Deoximation Reagent

 N-Methylpiperidinium chlorochromate adsorbed on alumina was found to be an efficient and selective reagent for the mild oxidative cleavage of oximes.     

A novel indium-catalysed synthesis of tetra-substituted pyridine derivatives

Indium trichloride was found to be an effective catalyst for the synthesis of various tetra-substituted pyridine derivatives via Michael addition of β-dicarbonyl compounds to α,β-unsaturated oximes and subsequent ring closure.     

Highly efficient aerobic oxidation of oximes to carbonyl compounds catalyzed by metalloporphyrins in the presence of benzaldehyde

Highly efficient oxidation of oximes to carbonyl compounds by molecular oxygen with benzaldehyde as an oxygen acceptor in the presence of metalloporphyrins has been reported. The simple structural manganese porphyrin showed an excellent activity for the oxidative deoximation reactions of various oximes. Moreover, different factors influencing oximes oxidation, that is, catalyst, solvent, and temperature, have been investigated. A possible mechanism for the deoximation reaction has been proposed.     

A convenient access to 1,5-anhydroketoses

A convenient, versatile entry into the 1,5-anhyroketose series is described and their conversion into enolones, enolone oximes and γ-pyrones.     

OXIDATIVE DEPROTECTION OF OXIMES USING PYRIDINIUM FLUOROCHROMATE AND HYDROGEN PEROXIDE

A simple convenient procedure of oxidative deoximation has been developed using pyridinium fluorochromate (PFC), in combination with 30% hydrogen peroxide. The method has been found to be effective for a wide range of aliphatic and aromatic oximes, and may be used for selective cleavage of aldoximes in the presence of ketoximes.     

3-H-YDROXYRETINAL AS A CHROMOPHORE OF Drosophila melanogaster VISUAL PIGMENT ANALYZED BY HIGH-PRESSURE LIQUID CHROMATOGRAPHY

Abstract— The chromophore of the visual pigment of the fruit fly Drosophila melanogaster was studied by high-pressure liquid chromatography (HPLC). Oxime derivatives of the chromophore were successfully analyzed with a more polar solvent than has been used for retinaloximes. A preceding monochromatic irradiation resulted in reversible interchanges in the amount among geometric isomers of the oximes that reflected the photointerconversion of rhodopsin and metarhodopsin of the peripheral photoreceptors (Rl-R6). Authentic all- trans -3-h-ydroxyretinal was used to identify the chromophore from metarhodopsin. Results demonstrated that the chromophore of the visual pigment in Drosophila is 3-h-ydroxyretinal as was proposed in larger flies.     

Prediction of H-Bonding Motifs for Pyrazoles and Oximes Using the Cambridge Structural Database

H-bonding motifs for pyrazoles and oximes have been examined in the Cambridge Structural Database. The accessible surface of the N atoms has been found to be useful as a discriminator to divide structures into dimer and catemer motifs for both pyrazoles and oximes. Low accessibility favors dimers and tetramers and high values favor catemers and trimers. Total molecular volume shows some correlation for oximes, while high values favor dimers. Empirical rules were successfully applied to predict the motifs of eight new structures in the subsequent release of the CSD.