Reduction of O-acyl oximes

NaCNBH₃/AcOH and Et₃SiH/CF₃CO₂H were found to be excellent reducing reagents for oxime benzoates without cleaving the NO bond.     

New O-acyl derivatives of lariciresinol

Summary In an investigation of the composition of the extractive substance of the wood ofAbies sibirica Ledeb. andA. nephrolepis Maxim., new O-acylated lignans, previously unknown in nature, have been isolated. The structures of the two new compounds have been established by physicochemical methods and by independent synthesis: they are lariciresinol coumarate and ferulate.The PMR spectra of laricyl coumarate and laricyl ferulate were taken by G. A. Kalabin.Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 162–166, March–April, 1976.     

New O-acyl derivatives of lariciresinol

In an investigation of the composition of the extractive substance of the wood ofAbies sibirica Ledeb. andA. nephrolepis Maxim., new O-acylated lignans, previously unknown in nature, have been isolated. The structures of the two new compounds have been established by physicochemical methods and by independent synthesis: they are lariciresinol coumarate and ferulate. The PMR spectra of laricyl coumarate and laricyl ferulate were taken by G. A. Kalabin.     

Isobactins: O-acyl isopeptide prodrugs of teixobactin and teixobactin derivatives

The antibiotic teixobactin is a promising drug candidate against drug-resistant pathogens, such as MRSA and VRE, but forms insoluble gels that may limit intravenous administration. O-Acyl isopeptide prodrug analogues of teixobactin circumvent the problem of gel formation while retaining antibiotic activity. The teixobactin prodrug analogues contain ester linkages between Ile₆ and Ser₇, Ile₂ and Ser₃, or between both Ile₆ and Ser₇ and Ile₂ and Ser₃. Upon exposure to physiological pH, the prodrug analogues undergo clean conversion to the corresponding amides, with half-lives between 13 and 115 min. Prodrug analogues containing lysine, arginine, or leucine at position 10 exhibit good antibiotic activity against a variety of Gram-positive bacteria while exhibiting little or no cytotoxicity or hemolytic activity. Because O-acyl isopeptide prodrug analogues of teixobactin exhibit clean conversion to the corresponding teixobactin analogues with reduced propensity to form gels, it is anticipated that teixobactin prodrugs will be superior to teixobactin as drug candidates.

O-Acyl isopeptide prodrug analogues of the antibiotic teixobactin are stable and non-gelating at acidic pH but convert to the corresponding active teixobactin analogues at neutral pH, thus overcoming limitations in intravenous dosing of teixobactin.     

Reaction of O-acyl derivatives of polynitroalkanes with electrophilic reagents

Conclusions The O-acyl derivatives of polynitroalkanes (trinitromethane, dinitromethane and 1,1-dinitroethane) react with various electrophilic reagents to give the corresponding trinitro- and dinitromethyl derivatives.Translated from Izvestiya Akademiya Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 344–350, February, 1973.     

NMR spectroscopy of cyclopentane derivatives: I. Cyclopentane and cyclopentanone

The deuterium-decoupled 100 MHz p.m.r. ¹³C-satellite spectra for cyclopentanone-2, 2,5,5-d₄ (2)) and cyclopentane-1,1,2,2,3,3-d₆ (5) have been determined at several temperatures and the LAOCOON 3 derived spectral parameters related to molecular conformation. For 2, the data were found to be consistent with the half-chair conformation; for 5, the data were fitted to an unrestricted pseudorotation model.     

Azole- and δ2-azolinecarbaldehyde oximes and their derivatives

The PMR spectra of the E (syn) and some Z (anti) isomers of 1-methyl-substituted pyrazole-,imidazole-, ²-pyrazoline-, and ²-imidazolinecarbaldehyde oximes and their quaternary and bisquaternary ammonium derivatives in organic solvents and aqueous solutions with various states of the ionogenic groups are described. The influence of the configuration and of the ionization of the oxime group on the chemical shifts of the protons of the quaternary derivatives of the 1-methylazolecarbaldehyde oximes is discussed.For Communication I, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1099–1104, August, 1973.     

Azole- and δ2-azolinecarbaldehyde oximes and their derivatives

The production of 1-methyl-substituted pyrazole-, imidazole-, ²-pyrazoline-, and ²-imidazolinecarbaldehyde oximes is described. The alkylation of 1-methylimidazole-and 1-methyl-²-pyrazolinecarbaldehyde oximes with methyl iodide and ,-dihalo-genoalkanes forms quaternary and bisquaternary ammonium derivatives, respectively. The quaternary derivatives of 1-methylpyrazolecarbaldehyde oximes are obtained by the oximation of the corresponding quaternary derivatives of the aldehydes; the direct methylation of these oximes either does not take place or leads to the formation of nitrones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1093–1098, August, 1973.The melting points were determined on a Kofler block.     

Mass spectrometry of onium compounds—II. Carnitine and O-acyl derivatives

Carnitine and its O-acyl derivatives undergo two major pyrolytic reactions in the mass spectrometer. Firstly elimination of water from carnitine or acid from acylcarnitine takes place followed by intramolecular displacement and formation of crotonyl lactone and trimethylamine. Secondly intramolecular displacement occurs with formation of a substituted γ-lactone and trimethylamine. For the lower acid derivatives only the elimination pathway is important. For carnitine and higher derivatives both processes are important. The electron induced fragmentations of the major pyrolysis products are relatively simple. The most important pathways for the major components are discussed. The pyrolytic composition and mode of fragmentation are characteristic and can be used for identification purposes.     

Stereoselective synthesis of cycloheptanone derivatives via an intermolecular [5 + 2] cycloaddition reaction

[reaction: see text] A [5 + 2] cycloaddition reaction of a new five-carbon unit was developed on the basis of a dicobalt hexacarbonyl propargyl cation species. Under the influence of EtAlCl(2), [5-benzoyloxy-2-(triisopropylsiloxy)-1-penten-3-yne)]dicobalt hexacarbonyl reacted with enol triisopropylsilyl ethers to yield seven-membered dicobalt acetylene complexes in good yield. The reactions with cyclic enol silyl ethers as well as acyclic enol silyl ethers exhibited remarkably high diastereoselectivity. The cycloadducts can be easily converted into various kinds of cycloheptanone derivatives.     

Synthesis of Schiff bases from 1-naphthylamine and vanillin, vanillal, and their O-acyl derivatives

Previously unknown Schiff bases were synthesized by the condensation of 1-naphthylamine with vanillin, vanillal, and their O-acyl derivatives in ethanol.     

Synthesis of imidazole derivatives from α-hydroxylamino oximes (review)

Data on the synthesis of imidazoline N-oxides from -hydroxylamino oximes and -amino oximes are collected in this review. The transformations of imidazoline N-oxides into N-oxides of imidazoles and 2H- and 4H-imidazoles and stable iminoxyl radicals and some properties of the compounds formed are examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1310, October, 1973.     

Synthesis of amino acid derivatives of hydrazones and oximes of spirodihydropyranochromen-2-ones

Sulfur-and nitrogen-containing derivatives of spirodihydropyranochromen-2-ones at the exocyclic oxygen atom have been synthesized. Modification of the oximes and hydrazones of the spiro-substituted pyranocoumarins with N-substituted amino acids were carried out using activated ester and symmetrical anhydride methods. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 208–220, February, 2008.     

Effect of substituents on spectral,luminescent and time-resolved characteristics of 2,5-diarylidene derivatives of cyclopentanone

Spectral, luminescent and time-resolved characteristics of 2,5-dibenzylidenecyclopentanone and its symmetrical derivatives (bis(N,N-diethylamino-), dimethoxy-, tetramethoxy-, dimethylthio-, and bis-18- crown-6 derivative) have been studied in media of different polarity (cyclohexane, toluene, acetonitrile, DMSO, and methanol) at room temperature. The absorption maximum of dibenzylidenecyclopentanone shifts bathochromically by 15 nm with an increase in polarity of the medium (cyclohexane–methanol). The introduction of electron-donating substituents in the aromatic rings of dibenzylidenecyclopentanone also results in a bathochromic shift of the absorption maximum by 100–130 nm in the media of different polarity and shifts the fluorescence maximum by 130 nm relative to the maximum of the dimethoxy derivative. Upon laser irradiation of oxygen-free solutions of dibenzylidenecyclopentanone and its tetramethoxy- and bis-18-crown-6 derivatives in acetonitrile, the triplet state with a half-life time of 0.3–1 μs is generated. For dimethoxy-, dimethylthio-, tetramethoxy-, and bis-18-crown-6 derivatives of dibenzylidenecyclopentanone, the isomers with a lifetime of ~50 ms are formed.     

Synthesis and reactivity of O-acyl selenophosphates

The synthesis of several new O-acyl selenophosphates were investigated. The stability and reactivity of the products were studied and related to their structure.