Quinoline Oximes: Synthesis,Reactions, and Biological Activity. (Review)

Data on the production and the reactions of quinoline aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles based on quinoline oximes is examined separately. The main results from investigation of the biological activity of quinoline oximes are presented.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 163–190, February, 2005.     

O-carbamoyl oximes as potential analgesics

Preparation of oxadiazinones 2 , from α-anilinoacetophenone oximes and O-carbamoyl-2,3-dihydro-4-quinolinone oximes 3 , from quinolinones are described.     

Oximes of five-membered heterocyclic compounds with three and four heteroatoms 2. Synthesis of derivatives,reactions, and biological activity (Review)

Data on the reactions of triazole, tetrazole, dioxazole, oxadiazole, and thiadiazole aldoximes, ketoximes, and amidoximes, their synthesis, and the reactions of their derivatives are reviewed. The synthesis of new heterocycles based on the oximes of five-membered heterocyclic compounds with three and four heteroatoms is examined separately. The principal results from investigation of the biological activity of ethers of these oximes are also presented. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–990, July, 2008.     

Mass spectra of some syn- and anti-aromatic aldoximes

The mass spectra of eight pairs of geometric isomers of aromatic oximes and four other single aromatic oximes are reported. The loss of H₂O, HO and HCN are major fragmentations from the molecular ion of all the benzaldoximes studies; however, the loss of HCN from the molecular ion did not occur in the oximes of 9-phenanthraldehyde, 1-naphthaldehyde and 2-naphthaldehyde. The halogen substituted benzaldoximes eliminate HCNO and H₂CNO forming an additional fragmentation pathway from the molecular ion. In general, variations were found for each pair of syn- and anti-oximes but no consistent patterns could be found in the spectra for all the syn-isomers versus all of the anti-isomers. The geometric isomerism of four oximes previously reported in the literature have been established for the first time as anti-m-bromobenzaldoxime, syn-9-phenanthraldoxime, syn-1-naphthaldoxime and syn-2-naphthaldoxime. Three new oxime acetates were prepared and their mass spectra are discussed.     

Comparative analysis of 13C shielding constants stereospecificity in the silicon and germanium derivatives of acetylenic aldehyde and ketone oximes based on the 13C NMR spectroscopy and GIAO calculations

In the acetylenic aldehyde oximes with substituents containing silicon and germanium, the ¹³C NMR signal of the C‐2 carbon of triple bond is shifted by 3.5 ppm to lower frequency and that of the C‐3 carbon is moved by 7 ppm to higher frequency on going from E to Z isomer. A greater low‐frequency effect of 5.5 ppm on the C‐2 carbon signal and a greater high‐frequency effect of 11 ppm on the C‐3 carbon signal are observed in the analogous acetylenic ketone oximes. The carbon chemical shift of the C?N bond is larger by 4 ppm in E isomer relative to Z isomer for the aldehyde and ketone oximes. The ²⁹Si chemical shifts in the silicon containing acetylenic aldehyde and ketone oximes are almost the same for the diverse isomers. The trends in changes of the measured chemical shifts are well reproduced by the gauge‐including atomic orbital (GIAO) calculations of the ¹³C and ²⁹Si shielding constants. Copyright © 2009 John Wiley & Sons, Ltd.     

Pyrrole Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on the production methods and reactions of pyrrole aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles from the pyrrole oximes is examined separately. The principal results from investigation of the biological activity of pyrrole oximes are described.     

Indole and Isatin Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on methods for the production of isatin and indole aldoximes, ketoximes, and amidoximes and their reactions are reviewed. Individual syntheses of new heterocycles from indole and isatin oximes are discussed. The principal results from investigation of the biological activity of derivatives of the oximes are also presented.     

Furan and Thiophene Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on methods for the production of furan and thiophene aldoximes, ketoximes, and amidoximes and their reactions are reviewed. The synthesis of new heterocycles from furan and thiophene oximes and the biological activity of derivatives of the oximes are discussed individually.     

Pyridine Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on methods for the production of pyridine aldoximes, ketoximes, amidoximes, and their derivatives and their reactions are reviewed. The synthesis of new heterocycles from pyridine oximes is discussed separately. The principal results of research into the biological activity of the oximes are presented.     

Divergent synthesis of fully substituted isoxazoles and spiro-fused pyrazolin-5-ones from cyclopropyl oximes

Efficient and divergent synthesis of fully substituted isoxazoles and spiro-fused pyrazolin-5-ones is developed from cyclopropyl oximes based on selection of reaction conditions. Under Appel conditions (PPh₃/CBr₄), substituted isoxazoles were synthesized from cyclopropyl oximes via a ring-opening and intramolecular cyclization process, whereas by treatment of cyclopropyl oximes with p-toluenesulfonyl chloride in the presence of potassium hydroxide, spiro-fused pyrazolin-5-ones were obtained via tandem ketoxime tosylation and intramolecular cyclization.     

取代苯甲醛肟和取代苯乙酮肟电化学氧化机理的研究

研究了１０种取代苯甲醛肟和５种取代苯乙酮肟的电化学氧化机理。这二类肟的氧化电位随取代基吸电子能力的增大而增高，并与它们相应的Ｈａｍｍｅｔｔ常数有线性关系。它们在电化学氧化过程中均有ｉｍｉｎｏｘｙ自由基生成，但最后产物各不相同。用控制电位电解和紫外吸收光谱检法验证了部分电化学氧化产物。因此，电化学氧化法可作为由肟类产生ｉｍｉｎｏｘｙ自由基的一种方法。     

Photochemical radical cyclization of γ,δ-unsaturated ketone oximes to 3,4-dihydro-2H-pyrroles

3,4-Dihydro-2H-pyrroles are synthesized from γ, δ-unsaturated oximes by photochemical radical cyclization with 1,5-dimethoxynaphthalene (DMN) as the sensitizer. The cyclization of alkyl ketone O-acetyloximes proceeds via photosensitized electron transfer in the presence of acetic acid, while conjugated oximes of aryl and α,β-unsaturated ketones are cyclized via energy transfer.     

Oximes of azolecarbaldehydes and Δ2-azolinecarbaldehydes and their derivatives

The configurational (kinetic) stability of the anionic and zwitterionic forms of 1-methylpyrazolecarbaldehyde oximes and 1-methylimidazolecarbaldehyde oximes and their quaternary ammonium derivatives in aqueous solutions has been established. In an acid medium, isomerization takes place and an E-Z equilibrium of the cations of the oximes is established. The changes in the relative thermodynamic stabilities of the stereoisomers of the heteroaromatic carbaldehyde oximes as functions of the size and nature of the ring, the position of the oxime group, and the steric loading are due to spatial factors and electrostatic interactions. To substantiate the preferred conformations of the Z aldehyde oximes the differences in the values of the chemical shifts of the protons of the ring and the rates of their deuterium exchange have been used.For Communication II, see [1],Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1176–1180, September, 1973.     

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     

Divergent Synthesis of Oxa-Cyclic Nitrones through Gold(I)-Catalyzed 1,3-Azaprotio Transfer of Propargylic α-Ketocarboxylate Oximes: Experimental and DFT Studies

1,3-Azaprotio transfer of propargylic α-ketocarboxylate oximes, a new type of alkynyl oximes featuring an ester tether, has been explored by taking advantage of gold catalysis. The incorporation of an oxygen atom to the chain of alkynyl oximes led to the formation of two different oxa-cyclic nitrones. It was found that internal alkynyl oximes with an E-configuration deliver five-membered nitrones, whereas terminal alkynyl oximes with an E-configuration afford six-membered nitrones. DFT calculations on four possible pathways supported a stepwise formation of C−N and C−H bonds, in which a 1,3-acyloxy-migration competes with the 1,3-azaprotio-transfer, especially in the case of internal alkynyl oximes. The relative nucleophilic properties of oxygen in the carbonyl group and the nitrogen in the oxime, the electronic effects of alkynes, and the influence of the ring system have been investigated computationally.     

Quinone-sensitized steady-state photolysis of acetophenone oximes under aerobic conditions: kinetics and product studies

Oxidation of oximes via photosensitized electron transfer (PET) results in the formation of the corresponding ketones as the major product via oxime radical cations and iminoxyl radicals. The influence of electron-releasing and electron-accepting substituents on these reactions was studied. The observed substituent effect strongly supports formation of iminoxyl radicals from the oximes via an electron transfer-proton transfer sequence rather than direct hydrogen atom abstraction. Correlation of the relative conversion of the oximes with Hammett parameters shows that radical effects dominate for the meta-substituted acetophenone oximes (rho(rad)/rho(pol) = 5.4; r2 = 0.93), whereas the para-substituted oximes are influenced almost equally by radical and ionic effects (rho(rad)/rho(pol) = -1.1; r2 = 0.98). From these data sets we conclude that the follow-up reactions proceed through a number of intermediates with both radical and ionic character. This was confirmed by product studies with the use of an isotopically labeled nucleophile. In addition to the major oxidation product (ketone), a chlorine-containing product was often identified as well. Studies on the formation of this product show that the most likely pathway is either via a direct nucleophilic addition in a complex formed between the oxime radical cation and the chloranil radical anion or via a radical substitution (SH2) mechanism. These studies show that with the increasing use of oximes as drugs and pesticides, intake of these chemicals followed by enzymatic oxidation may result in the formation of a variety of reactive intermediates, which may lead to cell and tissue damage.     

E- and Z-isomerism of 2-acetylthiophene oximes

A study on the oximation of a number of 2-acetylthiophenes in order to ascertain the validity of contradictory results previously described is reported. The fact that the steric hindrance is smaller in 2-acetylthiophenes unsubstituted at position-3 than in acetylbenzenes allows in these cases the formation of Z oximes, which even can predominate on the E oximes in the case of a + M substitution at position-5. In the paper is also shown that the E/Z ratio of 2-acetylthiophene oximes can be deduced from the ¹H-nmr spectrum of the crude oxime mixture.     

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.     

Synthesis and three-dimensional structure of 2-arylidene-3-oxoquinuclidine oximes

2-Arylidene-3-oxoquinuclidine oximes were obtained from the products of condensation of 3-oxoquinuclidine with aromatic aldehydes. It is shown that three of the four theoretically possible isomers (isomerism involving the C=C and C=N bonds) are formed; their thermal stability was studied. The structures of the isomeric oximes was established on the basis of data from the ¹H and ¹³C NMR spectra and were confirmed by data from chromatographic mass spectrometry and the UV and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 666–674, May, 1981.     

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.