Heterocyclic tautomerisms. II. An investigation of the 2-arylbenzothiazoline 2-(benzylideneamino)thiophenol tautomerism. Part 2

The reaction between 4-mercaptoaniline and various aromatic aldehydes was studied as a model system in order to determine which type of substitution on the aryl group in 2-arylbenzothiazolines (1) might give rise to the greatest possible stabilization of the hypothetical 2-(benzylideneamino)thiophenol tautomer (II). Regardless of electronic effect of substituents, most aldehydes reacted with 4-mercaptoaniline to form poly[4-(benzylideneamino)thiophenols] (III). Aromatic aldehydes substituted in the 2 position with the hydroxyl function reacted to form the stable, monomeric 4-(benzylideneamino)thiophenols (IV). This stabilization in the monomeric state is presumed to be due to the hydrogen-bonded nature of these compounds (V). Both monomeric and polymeric compounds reacted with benzalacetophenone in the presence of a basic catalyst in the manner to be expected of the 4-(benzylideneamino)thiophenol structure (IV) yielding correspondingly substituted 1,3-diphenyl-1-[4-(benzylideneamino)phenylthio]-3-propanones (VI).     

Heterocyclic tautomerisms. I. An investigation of the 2-arylbenzothiazoline-2-(benzylideneamino)thiophenol tautomerism. Part 1

A definite tautomeric relationship has been found between 2-arylbenzothiazolines (I) and 2-(benzylideneamino)thiophenols (II). In a reaction characteristic of the closed ring structure (I), 2-arylbenzothiazolines were oxidized in high yield with benzoyl peroxide to the corresponding 2-arylbenzothiazoles (III). Reactions characteristic of the open ring structure (II) include the formation of the potassium salt of the open ring structure (IV) by reaction of 2-arylbenzothiazolines with potassium t-butoxide in toluene and oxidation of 2-arylbenzothiazolines to bis-[2-(benzylideneamino)phenyl] disulfides (V) by hydrogen peroxide in methanol.     

Zum Mechanismus massenspektrometrischer Fragmentierungsreaktionen: XI—Einfluß von Substituenten auf die Bildung cyclischer Fragment-Ionen in den Massenspektren von N,N-Dimethyl-N′-2-chlorphenylformatmidinen und 2-Chlorformaniliden

Molecular ions of N,N-dimethyl-N′-2-chlorophenylformamidines (III) and 2-chloroformanilides (IV) lose a chlorine atom to give benzimidazolium and benzoxazolium ions, respectively. As with N,N-dimethyl-N′-phenylformamidines (I), a linear relationship exists between the Hammett σ-constants and the effect of substituents on the ionisation potentials of substituted III and IV. In contrast to this, the appearance potentials of the cyclic fragment ions of III and IV cannot be easily related to polar effects of substituents; these effects are similar for the cyclic fragment ions of I, III and IV however. Furthermore, the intensities of these ions are influenced in the same direction by substituents in the mass spectra of I, III and IV, and are strongly reduced by electron donating substituents in the para position. The formation of cyclic fragment ions in the mass spectra of I, III and IV therefore occurs by the same mechanism.     

2-氨基取代噻唑基膦酸脂的合成

本文报导一系列2-氨基-5-取代-4-噻唑基膦酸酯和2-氨基-4-取代-5-噻唑基膦酸酯的合成. 这类化合物显示了一定的杀菌活性.     

The synthesis of alkyl substituted 2-pyrazolines by the reaction of acids with hydrazine derivatives

A convenient synthesis of alkyl substituted 2-pyrazolines (III) has been developed from the reaction of acids with hydrazones (I) and azines (IV). An alkylidenebis-1-methyl-2-alkylidene-hydrazine (V) was isolated as an intermediate, in the preparation of 5-isopropyl-1,4,4- trimethyl-2-pyrazoline (IIId), and protonated vinylhydrazones (II) are proposed as common intermediates in the formation of III, IV and V. The 4,5-dialkyl-2-pyrazolines (IIIk-m) that were prepared were shown to be free of isomers by nmr. The thermal isomerization of IIIk-m to 3,4-dialkyl-2-pyrazolines (IIIn-o) was found to be incomplete at the temperatures studied. The reaction of IIIn-o with acetone afforded 3,4-dialkyl-1-[2-(2-methyl-4-oxopentyl)]-2-pyrazolines (IIIp-q). The nmr and mass spectral data of III are discussed.     

Synthesis of 2-(Substituted Benzylideneamino)-4-(4′-hydroxyphenyl) Thiazoles and Their O-Glucosides

2-Amino-4-(4′-hydroxyphenyl) thiazole 1a was prepared from reaction between p-hydroxyacetophenone, thiourea, and iodine; compound 1a was treated with several (aryl/hetro aryl) aldehydes to form 2-(substituted benzylideneamino)-4-(4′-hydroxyphenyl) thiazoles 2a–j, which were glucosylated by using acetobromoglucose as a glucosyl donor to afford 2-(substituted benzylideneamino)-4-(2, 3, 4, 6-tetera-o-acetyl-4′-o-β-d-glucosidoxyphenyl) thiazoles 3a–j, which further on during deacetylation produced 2-(substituted benzylideneamino)-4-(4′-o-β-d-glucosidoxyphenyl) thiazoles 4a–j. These compounds were evaluated for biological activity, and their structure was confirmed by IR, NMR, mass spectra, elemental, and chemical analysis.

     

Luminol-K2S2O8体系中金属离子化学发光行为的研究

报导了在自行设计的流动注射式化学发光分析仪上,对Luminal-K2S2O8体系中32种金属离子的化学发光行为的系统研究.确定了对金属离子的最优测定条件以及大多数金属离子的检出极限和线性范围.     

Charge localization in molecule-ions upon electron-impact. Mass spectra of some substituted 1-carbamoyl- and 1-thiocarbamoyl-2-pyrazolines and related compounds

The mass spectra of some substituted 2-pyrazolines and a pyrazolidine are discussed. With the exception of III which favours McLafferty rearrangements prior to fragmentation, I, IV and V fragment to give isocyanate or isothiocyanate radicals and ions with structures corresponding to their heterocyclic molecular compounds. These results which can be explained in the light of the concept of charge localization at preferential sites, are in good agreement with the ionization potential studies on substituted ureas and thioureas.⁵ Other compounds show simple straight-forward fragmentations upon electron-impact.     

Isoquinoline derivatives VI. Synthesis and pharmacological properties of 4,6,7-substituted 1(2)-arylalkyl-1,2,3,4-tetrahydroisoquinolines and their analogs

The condensation of 6,7-dimethoxy-1,2.3.4-tetrahydroisoquinoline (II) with diphenylacetyl and diphenylpropionyl chlorides gave the corresponding amides (III). Reduction of III with lithium aluminum hydride converted them to tertiary amines IV, which were characterized as their hydrochlorides. The condensation of equimolecular amounts of amines I with the acid chlorides of substituted phenylacetic and diphenylpropionic acids gave amides V. The reduction of amides V with lithium aluminum hydride gave secondary amines VI. The corresponding tetrahydroisoquinolines (VII) were obtained by the cyclization of amides V and subsequent reduction with lithium aluminum hydride, The condensation of 1-diphenylethyl-6,7-dimethoxy-l,2,3,4-tetrahydroisoquinoline with formalin gave VIII. The IR spectra of the synthesized compounds were examined. The effect of these compounds on the arterial blood pressure and the coronary blood flow was studied.See [1] for communication V.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1683–1687, December, 1971.     

Electron transfer. 157. Reactions of hypervalent manganese species with S(2) metal-ion reductants

Solutions of the complexes of hypervalent manganese, [Mn(III)(C(2)O(4))(3)](3)(-) (in oxalate buffers), [Mn(IV)(bigH)(3)](4+) (in biguanide buffers), and [(bipy)(2)Mn(III)(O)(2)Mn(IV)(bipy)(2)](3+) (in bipyridyl buffers) may be reduced by s(2) center reductants In(I), Sn(II), and Ge(II), yielding Mn(II) quantitatively. In all cases, rates are determined by the initial act of electron transfer, giving an s(1) transient (In(II), Sn(III), or Ge(III)); subsequent steps are rapid and kinetically silent. The In(I)-Mn(III) and Ge(II)-Mn(III) reactions are inhibited by added oxalate, whereas the Sn(II)-(Mn(III)Mn(IV)) reaction is strongly accelerated by Cl(-). The In(I)-Mn(IV) reaction is complicated by formation of a 1:1 addition compound In(I).Mn(IV). We find no evidence for two-unit steps in any of these systems.     

Reaction of 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene with hydrazines

2-Methyl-3-ethoxycarbonyl-4-(N,N-dimethylhydrazino)thiophene (II) and 2-methyl-3-ethoxy-carbonyl-4-(N-phenylhydrazino)thiophene (III) are formed by the action of substituted hydrazines — N,N-dimethylhydrazine and phenylhydrazine — on 2-methyl-3-ethoxycarbonyl-4-hydroxythiophene (I). At the same time, the thiophene ring of hydroxythiophene I undergoes hydrazinolysis under the influence of hydrazine hydrate to form 3-mercaptomethyl-4-ethoxycarbonyl-5-methylpyrazole (IV). Structure IV was proved by IR, UV, and PMR spectroscopy and by hydrogenolysis of IV to the known 3,5-dimethyl-4-ethoxycarbonylpyrazole (V).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 759–761, June, 1971.     

Heterocycles. Part XII. Synthesis of new benzo[6,7]cyclohepta[1,2-d]pyrimidine

Selected 2-arylidene-1-benzosuberones I were condensed with guanidine hydrochloride to give the corresponding substituted 2-aminopyrimidines II and III respectively. Condensation of chalcones I with benz-amidine hydrochloride revealed the formation of the corresponding substituted 2-phenylpyrimidines IV. The structure of all products was substantiated by chemical and spectroscopic methods.     

Effect of trimethylsilyl substitution on the structure and properties of phthalocyanine: A density functional theory study

The geometries of four isomers of the trimethylsilyl substituted phthalocyanine (Pc)— I , II , III , and IV —have been optimized at the B3LYP/3‐21G level of density functional theory. Normal‐mode vibrational analyses have been performed and their standard thermodynamic functions, molar fractions, and electronic absorption spectra calculated. Single‐point energies have been calculated at the B3LYP/6‐311G* level for all isomers to evaluate the heats of formation from an isodesmic reaction. It is found that substitution has little influence on the geometry and electronic structures of the Pc framework. The corresponding geometric parameters in various isomers are close. According to the B3LYP/6‐311G*//B3LYP/3‐21G results, substitution at the peripheral position of the isoindole with an inner hydrogen is most favorable. The energies increase in the order of IV < II < III < I , and the energy difference between IV and I is 5.75 kJ/mol. The molar fractions of IV , II , III , and I are 0.80, 0.17, 0.02, and 0.02 and the heats of formation are 2009.96, 2010.10, 2015.85, and 2016.52 kJ/mol, respectively. This indicates that nonperipheral substituted Pcs have higher energy and little production because they are not stable under the considered conditions. The electronic spectra of the substituted Pcs calculated using the ZINDO method have two strong Q absorption bands around 700 nm and one B band around 300 nm that are slightly shifted compared with those in Pc. The ratios of the oscillator strength of the B band to the Q bands are much lowered by trimethylsilyl substitution. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Austauschreaktionen an komplexgebundenen liganden von elementen der IV. Hauptgruppe : II. Aminolyse von cyclopentadienyl-dicarbonyl-trichlorsilyl-eisen

The ¹H and ¹³C NMR spectra of the following six compounds have been examined over a wide range of temperatures: four derivatives of 3,5-dimethylpyrazole substituted at the nitrogen atom by organometallic groups such as Si(CH₃)₃ (I), Si(C₂H₅)₃ (II), Si(OC₂H₅)₃ (III), Ge(CH₃)₃ (IV), 3,5-dimethyl-1-trimethylsilyl-1,2,4-triazole (V) and 1-trimethylsilylimidazole (VI). Activation energies of the metal migration have been found for the compounds (I–V) by the total NMR line-shape analysis. Proton and carbon spectra of the compound (VI) show equivalence of the positions 4 and 5 in the imidazole ring. No temperature-dependent changes in the spectra were observed at –80 to +80°. These facts may be interpreted by assuming that the organometallic group undergoes an intermolecular exchange.     

Synthesis, structure, and characterisation of a new phenolato-bridged manganese complex [Mn2(mL)2]2+: chemical and electrochemical access to a new mono-mu-oxo dimanganese core unit

The dinuclear phenolato-bridged complex [(mL)Mn(II)Mn(II)(mL)](ClO(4))(2) (1(ClO(4))(2)) has been obtained with the new [N(4)O] pentadentate ligand mL(-) (mLH=N,N'-bis-(2-pyridylmethyl)-N-(2-hydroxybenzyl)-N'-methyl-ethane-1,2-diamine) and has been characterised by X-ray crystallography. X- and Q-band EPR spectra were recorded and their variation with temperature was examined. All spectra exhibit features extending over 0-800 mT at the X band and over 100-1450 mT at the Q band, features that are usually observed for dinuclear Mn(II) complexes. Cyclic voltammetry of 1 exhibits two irreversible oxidation waves at E(1)(p)=0.89 V and E(2)(p)=1.02 V, accompanied on the reverse scan by an ill-defined cathodic wave at E(1')(p)=0.56 V (all measured versus the saturated calomel electrode (SCE)). Upon chemical oxidation with tBuOOH (10 equiv) at 20 degrees C, 1 is transformed into the mono-mu-oxo species [(mL)Mn(III)-(mu-O)-Mn(III)(mL)](2+) (2), which eventually partially evolves into the di-mu-oxo species [(mL)Mn(III)-(mu-O)(2)-Mn(IV)(mL)](n+) (3) in which one of the aromatic rings of the ligand is decoordinated. The UV/Vis spectrum of 2 displays a large absorption band at 507 nm, which is attributed to a phenolate-->Mn(III) charge-transfer transition. The cyclovoltammogram of 2 exhibits two reversible oxidation waves, at 0.65 and 1.16 V versus the SCE, corresponding to the Mn(III)Mn(III)/Mn(III)Mn(IV) and Mn(III)Mn(IV)/Mn(IV)Mn(IV) oxidation processes, respectively. The one-electron electrochemical oxidation of 2 leads to the mono-mu-oxo mixed-valent species [(mL)Mn(III)-(mu-O)-Mn(IV)(mL)](3+) (2 ox). The UV/Vis spectrum of 2 ox exhibits one large band at 643 nm, which is attributed to the phenolate-->Mn(IV) charge-transfer transition. 2 ox can also be obtained by the direct electrochemical oxidation of 1 in the presence of an external base. The 2 ox and 3 species exhibit a 16-line EPR signal with first peak to last trough widths of 125 and 111 mT, respectively. Both spectra have been simulated by using colinear rhombic Mn-hyperfine tensors. Mechanisms for the chemical formation of 2 and the electrochemical oxidation of 1 into 2 ox are proposed.     

A chemiluminescence method for the detection of electrochemically generated H2O2 and ferryl porphyrin

Electrochemical formation of H2O2 and the subsequent ferryl porphyrin were examined by measuring luminol chemiluminescence and absorption spectrum using flow-injection method. Emission was observed under the cathodic potential (0.05 V at pH 2.0 and -0.3 V at pH 11.0) by the electrochemical reduction of buffer electrolytes solution but no emission was observed at anodic potentials. Fe(III)TMPyP solution was added at the down stream of the working electrode and was essential for the emission. Removal of dissolved O2 resulted in the decrease of emission intensity by more than 70%. In order to examine the lifetime of reduced active species, delay tubes were used in between working electrode and Fe(III)TMPyP inlet. Experimental results suggested the active species were stable for quite long. The emission was quenched considerably (>90%) when hydroperoxy catalase was added at the down stream of the working electrode whereas SOD had little effect. Significant inhibition of the emission by the addition of alkene at the down stream of the Fe(III)TMPyP inlet was considered as evidence of oxo-ferryl formation. The spectra at reduction potential under aerated condition were shifted to the longer wavelength (>430 nm) compared to the original spectrum of Fe(III)TMPyP (422 nm). All the spectra were perfectly reproduced by a combination of Fe(III)TMPyP and O=Fe(IV)TMPyP (438 nm) spectra. These observations lead to the conclusion that H2O2 was produced first by electrochemical reduction of O2, which then converted Fe(III)TMPyP into O=Fe(IV)TMPyP to activate luminol. The current efficiencies for the formation of H2O2 were estimated as about 30-65% in all over the pH.     

Reaction of ethyl γ-bromo-β-methoxycrotonate with carbonyl compounds. Synthesis of 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones and 3-substituted 3-pyrazolin-5-ones

Ethyl β-methoxycrotonate I reacts with substituted carbonyl compounds II in benzene to give 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones III. The reaction of IIIa and j with hydrazine hydrate in ethanol leads to 3-[(1′-thienyl-1-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVa) and 3-[1′-styryl-1′-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVj) in good yields. The structure of the products were assigned and confirmed on the basis of their elemental analysis and the electronic absorption, infrared and nmr spectra.     

Synthesis of nitrogen‐containing heterocycles 10. Reaction of 2‐amino‐1h‐imidazole derivatives with ethoxymethylene compounds

The direct annelation reaction of 4‐substituted 2‐amino‐l‐benzylideneamino‐1H‐imidazoles ( 1 ) or 2‐amino‐1‐isopropylideneamino‐1H‐imidazole ( 8 ) with ethoxymethylenemalononitrile ( I ) gave successfully bicyclic imidazo[1,2‐a]pyrimidine compounds 2 and 9 in high yields. The reactions of other ethoxymethylene compounds of lower reactivity, i.e., ethyl ethoxymethylenecyanoacetate ( II ) and diethyl ethoxymethylenemalonate ( III ), with 2‐amino‐1H‐imidazoles under similar conditions afforded the corresponding enamines 3, 4 and 10 , which, upon heating in the presence of an acid or a base, could readily be cyclized to form imidazopyrimidines except for 1‐isopropylideneamino compound 10 . In general, the 3‐phenyl compounds ( 3b and 4b ) did not cyclize to the type 2 compound resulting in a full recovery of the starting enamines.     

The metal complexes of some azo and azomethine dyestuffs : Part I. Spectra in water,and in dioxan/water in the wavelength range 320-600 mμ

The visible, spectra of the highly sensitive colorimetric reagent 4-(2-pyridylazo)-resorcinol (I), and of the coloured cpmplexes formed with copper(II), nickel(II), cobalt(II), lead(II), and uranium(VI) were obtained in water and in aqueous dioxan. The structures of these complexes were determined by spectrophotometric methods, and chelation by (I) established as essentially terdentate. Comparison is made with the visible spectra of salicylidene-2-aminopyridine (II), 2-(o-hydroxy-phenyl-imino-methyl)-pyridine (III), and benzeneazoresorcinol (IV), and of the metal complexes of (II) (III) and (IV). The red coloration obtained with 4-(2-pyridylazo)-resorcinol is explained by the presence of a pseudo-phenanthroline system and an o-o'-disubstituted azo system, the active groups in chelation being the pyridine nitrogen atom, the azo nitrogen farthest from the heterocycle, and the o-hydroxyl group.     

Metal Complexes with Macrocyclic Ligands,VI. The role of substituents on the complexation rate of transition metal ions with several 1,4,7,10-tetraazacyclotridecanes

12,12-Dimethyl-1,4,7,10-tetraazacyclotridecane (I), 11,13-dimethyl-1,4,7,10-tetraazacyclotridecane (II), 11,11,13-trimethyl-1,4,7,10-tetraazacyclotridecane (III) and 1,4,7,10,12,12-hexamethyl-1,4,7,10-tetraazacyclotridecane (IV) have been synthesized and their properties are described. While the Ni²⁺ and Cu²⁺ complexes of I–III have square planar geometries, those of IV are pentacoordinate according to their absorption spectra. Similarly, while the Co²⁺ complex of I is octahedral and readily oxygenated, the analogous complex with IV is pentacoordinate and not sensitive to oxygen. The rate of complexation of these ligands with Cu²⁺ and Ni²⁺ decreases in the order I > II > III ? IV, indicating that the number as well as the position of the methyl groups are important. Finally for Cu²⁺ the formation of the thermodynamic stable end product is slown down by methyl substitution in α-position to the coordinating nitrogen atoms (ligand II and III) so that an intermediate can be observed, whereas with I Cu²⁺ directly forms the end product.