Thio Analogs of Pyrimidine Bases: Syntheses,EIMS and 13 C NMR Study of New Ortho -( Meta - and Para -) Substituted Derivatives of 2-benzylthio-5-bromo-6-methyluracils

Nine new ortho -( meta - and para -) substituted derivatives of 2-benzylthio-5-bromo-6-methyluracils have been prepared. EI induced mass spectral fragmentation of these compounds was investigated. Fragmentation pathways are proposed on the basis of accurate mass and metastable transitions measurements. The correlation between the intensities of the M +. and the selected fragment ions of these compounds is discussed. 13 C NMR spectra of these compounds were assigned. The data derived from EIMS and 13 C NMR spectra can be used to differentiate the isomers.     

EIMS study of new isomeric N-substituted hydrazones of 2-(3- and 4-)-pyridinecarboxaldehydes

EI induced mass spectral fragmentations of twelve new hydrazones of 2-(3- and 4-)-pyridinecarboxaldehydes and hydrazides of (E)-stilbenyloxyacetic acid as well as N-(E)-stilbenyloxyalkylcarbonyl substituted amino acids were investigated. Fragmentations pathways are proposed on the basis of accurate mass and B/E linked scan spectra measurements. The correlation between the intensities of M^+. and the selected fragment ions of these compounds is discussed. The data obtained create the basis for distinguishing isomers.     

Electron impact induced fragmentation of some 7-(o- and p-R-benzylidene)-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles. I

The mass spectral fragmentation patterns of ten 7-(o- and p-R-benzylidene)-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles, I, obtained by electron impact have been studied. All the spectra analyzed contain molecular ions and the principal fragmentation routes take place either from the molecular ion, or from (M⁺-1) ion. Likewise, our investigation of the mass spectra of these compounds revealed interesting relationships between the substitution pattern in the framework of I and the fragmenation pathways.     

Electronic substituent effects in the electron impact mass spectrometry of 2-(arylazo)-4-phenylphenols

A mass spectrometric study of a set of six novel 2-(arylazo)-4-phenylphenols 1-6 was performed. The electron impact spectra were acquired and analyzed for five of the compounds in order to establish a fragmentation pattern. The suggested pathways were investigated and confirmed by means of tandem mass spectrometry (MS/MS) experiments together with high-resolution accurate mass data. However, the sixth molecule, a sodium sulfonate salt, was studied using fast atom bombardment (FAB) ionization in positive and negative modes. In addition, some electronic substituent effects were investigated by analyzing Hammett-McLafferty linear free energy correlations for some peaks derived from the corresponding molecular ions. Also, the role of the O-H...N hydrogen bond present in the target compounds was analyzed. The roles of these H-bonds were consistent with the corresponding acidity constant values obtained experimentally as well as by theoretical quantum chemistry calculations using HF/6-31 + G(d,p) and B3LYP/6-31G(d,p). Some spectrometric data were correlated with topological properties derived from the atoms-in-molecules (AIM) theory.     

Synthesis of N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles and their properties

N-alkyl- and N-(β-hydroxyalkyl)-2-(acylmethylthio)benzimidazoles have been obtained by the reaction of N-alkyl- and N-(β-hydroxyalkyl)benzimidazoline-2-thiones with α-haloketones. The structures of the substances synthesized have been confirmed by IR, PMR, and mass spectra. The biological properties of the compounds obtained have been studied.     

Mass spectra of 1-(2′-hydroxy-5′-alkylphenyl)-1-alkanone (E)-oximes

The mass spectra of 1-(2′-hydroxy-5′-alkylphenyl)-1-ethanone (E)-oximes 1–6 and 1-(2′-hydroxy-5′-methylphenyl)-1-alkanone (E)-oximes 7–12 are given and the major fragmentation pathways discussed. The simultaneous loss of water and alkyl moieties from the molecular ion indicates that a skeletal rearrangement take place and a cycloheptatrienyloheterocyclic system is formed. The McLafferty rearrangement, γ-fission in the side aliphatic chain and oxygen expulsion are discussed with evidence being drawn from accurate mass measurements, metastable ions and comparison with mass spectral data of related compounds.     

Liquid chromatographic and mass spectral analysis of 1-(3,4-methylenedioxyphenyl)-1-propanamines: regioisomers of the 3,4-methylenedioxyamphetamines

The title 1-(3,4-methylenedioxyphenyl)-1-propanamines represent positional isomers of the N-substituted 3,4-methylenedioxyamphetamines, clandestinely produced drugs frequently encountered by forensic laboratories. These propanamines are prepared by reductive amination of 3,4-methylenedioxypropiophenone with a series of N-alkylamines. Analytical methods are developed to distinguish these compounds from the MDA series. The ultraviolet spectra of the propanamines are very similar to those of the MDAs with absorption maxima at 284 and 236 nm. The propanamines are separated under reversed-phase liquid chromatographic conditions by using a C18 stationary phase and a mobile phase of acidic (pH 3) acetonitrile containing methanol and triethylamine. The relative retention properties of these compounds parallel those observed in the MDA series. The electron impact mass spectra of the propanamines are determined by GC-MS, and the fragmentation pattern clearly distinguishes these compounds from those of the MDA series having the same molecular weight.     

Investigation of 4-(nitrophenylamino)pent-3-en-2-ones and 4-(nitrobenzylamino)pent-3-en-2-ones by electron ionization mass spectrometry. Observation of characteristic ortho effects

The compounds 4-(phenylamino)pent-3-en-2-ones (1-3) and 4-(benzylamino)pent-3-en-2-ones (4-6) substituted with a nitro group on the aromatic ring were studied by electron ionisation mass spectrometry (EIMS). It was deduced that the compounds 1-3 are converted into the tautomeric 4-(arylimino)pentan-2-one during the EI process. Mass spectrometric decompositions of ortho-substituted derivatives (1 and 4) were found to be different from those observed for meta- and para-isomers. The fragmentation pathways are discussed on the basis of data from linked B/E and B(2)/E scans, mass-analysed ion kinetic energy (MIKE) spectra, accurate mass measurements and isotope labelling.     

Synthesis of 5-(1 -naphthylmethyl)-4-aryl-s-triazole-3-thiol/yl-thioglycolic acids as possible anti-inflammatory agents

Several 5-(1-naphthylmethyl)-4-aryl-S-triazoIe-3-thiol/yl-thioglycolic acids were prepared as possible anti-inflammatory agents. The infrared, nuclear magnetic resonance and mass spectra of these compounds are reported.     

Mass spectral fragmentation patterns of 2,5-bis(p-R2-phenyl)-(3,4)-R1-furans

The electron impact mass spectrometric fragmentation pathways for several 2,5-bis(p-R₂-phenyl)-(3,4)-R₁-furans, I, were investigated. Our investigation of the mass spectra of these compounds revealed interesting relationships between substitution pattern in the framework of I and the fragmentation patterns.     

Stereoselective Syntheses and Biological Properties of (E)-α-(Methoxyimino)-2-[1-(aryloxy)methyl]-benzeneacetates

(E)-α-(Methoxyimino)-2-[1-(aryloxy)methyl]-benzeneacetates, the analogues of Kresoxim-methyl, were stereoselectively synthesized with the coupling reaction of 2-methylphenyldiazonium chloride and methyl 2-hydroxyiminoacetate in the presence of CuSO4/Na2SO3 as a key step, and it was first found that the coupling reaction could give the key intermediate material(E)- and(Z)-methyl 2-(hydroxyimino)-2-o-tolylacetate with a molar ratio of 14∶1. The(E)-configurations of all these compounds were assigned on the basis of their 2D-NOESY spectra of 1H NMR. The preliminary bioassays indicate that most of the compounds show an activity against a wide variety of fungi.     

Synthesis of 5-(1-naphthylmethyl)-4-aryl-s-triazol-3-thiols/ylthioglycolic acids as possible antiinflammatory agents

Several 5-(1-naphthylmethyl)-4-aryl-s-triazol-3-thiols/ylthioglycolic acids were synthesized as possible anti-inflammatory agents. The interpretation of infrared, nuclear magnetic resonance, and mass spectra is discussed for chemical characterization of these compounds.     

5-乙酰(苯甲酰)基-4-芳基-3,4-二氢嘧啶-2(1H)-酮的质谱裂解规律

Using high resolution capabilities of a time-of-flight instrument and ion trap tandem technique, electron impact mass spectra of 5-acetyl (benzoyl)-4-aryl-3,4-dihydropyrimidin-2 (1H)-ones 1-5 were studied. The molecular ion (M) peaks for 1-3 can be found in the spectra with high abundances, but very weak for 4 and 5,in which strong electron-attracting substituents are attached to the benzene ring. The main fragmentation pathways for 1-5 include the cleavage of (M-Ar) + with high intensity, (M-RCO) + with moderate abundance, (M-H) +with high intensity for the compounds without strong electron-attracting substituent in the aromatic ring, and the pyrimidine ring cleavage (loss of neutral NH=C=X). In addition, a prominent cation (Ph + , m/z 77) can be found in the low mass region of the spectra for all the compounds, which give rise by different pathways between 1- 2 and 3-5. Several additional fragmentations for individual compounds are proposed.     

N-dealkylation of 2-(tert-butyl)-3-hydroxy-3-(4-chlorophenyl)isoindolinone and n-(tert-alkyl)-2-aroylbenzamides in concentrated sulfuric acid

It has been established that 2-(tert-butyl)-3-hydroxy-3-(4-chlorophenyl)isoindolinone and N-(tert-Alkyl)-2-aroylbenzamides are dealkylated in concentrated sulfuric acid to give 3-hydroxy-3-arylisoindolinones. The reaction is realizable. only when there is a tert-alkyl group attached to the nitrogen atom. The reaction mechanism is discussed on the basis of data on the change with time in the electronic spectra of the investigated compounds in concentrated sulfuric acid and a comparison with the spectra of model structures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 763–765, June, 1977.     

N-(S)-(1’-氯甲基-2’-烷基)-2-乙基-2-(4S-烷基-4,5-二氢噁唑)丁酰胺的合成

由L-氨基酸不对称合成了4种新型手性化合物(6a,6b,7a,7b),其结构经IR,~1H NMR,~(13)C NMR及MS等证实。     

Synthesis of 2-(p-R-benzoylmethylene)-3-(p-R-phenyl)-1H-quinoxalines

The reaction of 1,2-diaminobenzenes with substituted 1,2-dibenzoyl-1,2-dibromoethanes constitutes a convenient synthetic route to the hitherto 2-(p-R-benzoylmethylene)-3-(p-R-phenyl)-1H-quinoxalines. Structures of all products were elucidated by ir, ¹H and ¹³C-nmr, mass spectra data. X-Ray crystallography data confirm assigned structures.     

Novel Synthesis of Isoquinoline Derivatives Derived from (Z)-4-(1,3-Diphenylpyrazol-4-yl)isochromene-1,3-dione

A series of isoquinoline derivatives were synthesized via the reaction of the (Z)-4-(1,3-diphenylpyrazol-4-yl)isochromene-1,3-dione with different hydrazides, primary amines, diamines, 2-aminothiophenol, 2-aminobenzoic acid, p-aminoacetophenone, and ethyl 2-amino-4,5,6,7-tetrahydrobenzo-[b]thiophene-3-carboxylate. All the synthesized compounds were characterized by infrared, ¹H NMR, and mass spectra besides the analytical data.     

Synthesis,characterization and antibacterial activity of 1-([6-bromo-2-hydroxy-naphthalen-1-yl]arylphenyl)methyl)-3-chloro-4-(arylphenyl)-azetidin-2-one

One-pot synthesis of 1-([6-bromo-2-hydroxy-naphthalen-1-yl]-aryl-phenyl)methyl)-3-chloro-4-(aryl-phenyl)azetidin-2-ones has been reported in the present research work via Staudinger [2 + 2] ketene-imine cycloaddition reaction pathway. The reaction of 1-((Benzylideneamino)(aryl)methyl)-6-bromo-naphthalen-2-ols with chloroacetic acid and triethylamine afforded 1-([6-bromo-2-hydroxynaphthalen-1-yl]aryl-phenyl)methyl)-3-chloro-4-(aryl-phenyl)azetidin-2-ones. For the structural elucidation of series of compounds, different analytical and spectroscopic techniques such as elemental analysis, IR spectra, ¹H-NMR spectra and mass spectra were used. All the newly synthesized compounds were tested for their anti-bacterial activity studies. It revealed that some of the compounds possesses moderate to good activities as compared to standard drugs. The widest spectrum of anti-bacterial activities against both gram-positive and gram-negative bacterial strains among the examined compounds possessed having more hydroxyl group along with β-lactam ring compared to other substituted azetidinones.     

Liquid Chromatographic and Mass Spectral Analysis of 1-(3,4-Methylenedioxyphenyl)-1-ethanamines: Homologues of 3,4-Methylenedioxyamphetamines

Abstract

The deletion of a methylene unit from the arylamine side chain of the 3,4-methylenedioxyamphetamines (MDAs) produces the homologous 1-(3,4-methylenedioxyphenyl)-1-ethanamines. These ethanamines were prepared via reductive amination of the corresponding ketone with a series of N-alkylamines. Analytical methods were developed to distinguish these compounds from the MDA series. The ethanamines were separated under reversed-phase1 iquid chromatographic conditions using a c18 stationary phase and a mobile phase of aqueous acidic (pH3) acetonitrite containing triethylamine. The electron impact mass spectra of the ethanamines were determined by GC-MS and the fragmentation pattern clearly distinguishes these compounds from those of the MDA series having the same molecular weight.     

Spectral-luminescent and solvatochromic properties of 2-(3-coumarinyl)-5-(2′-(R-amino)-phenyl)-1,3,4-oxadiazoles

Spectral-luminescent properties of the newly synthesized 2-(3^′-coumarinyl)-5-(2′-(R-amino)-phenyl)-1,3,4-oxadiazoles has been investigated in solvents of various polarity and hydrogen-bonding ability. It has been found that for all the studied compounds no excited state intramolecular proton transfer occurs despite the presence of coumarinyl fragment - electron acceptor effect of the coumarinyl fragment is not sufficient to increase the excited state acidity of the amino group. It has been found that the absorption spectra of the studied compounds shift to higher energy with increase in solvent polarity, whereas corresponding fluorescence spectra shift to lower energy with solvent polarity increase. It has been suggested that long-wavelength shifts of the fluorescence spectra of the studied compounds with increase in solvent polarity is caused by the solvent relaxation. The observed solvent relaxation effect allow us to propose some of the studied compounds as potential probes to monitor changes in solvent relaxation in low-polar media and as potential probes for rigidochromic effect.