A new method of synthesis of some 2-aryl and 2-heterocyclic benzimidazole,benzoxazole and benzothiazole derivatives

A new one-step facile method for the synthesis of some benzimidazole, benzoxazole and benzothiazole derivatives is described. The method involves the action of aromatic and heterocyclic selenoamides on some o-phenylenediamine, o-aminophenol and o-aminothiophenol and their derivatives.     

Cationic oligomerization and polymerization of some propenylbenzene derivatives

A comparative study was undertaken of the cationic oligomerization/polymerization of the natural propenylbenzene derivatives, anethole, isoeugenol, and isosafrole, together with synthetic o-methoxypropenylbenzene and N,N-dimethyl-p-propenylaniline using boron trifluoride diethyletherate as catalyst. Two (optimum) reaction temperatures were employed, ?12 and ?45°C, and only the (E) isomers of the monomers were studied. The order of reactivity of the monomers was found to be anethole > isoeugenol > isosafrole > o-methoxypronylbenzene as measured by following the rate of loss of monomer by proton magnetic resonance spectrometry at ?12°C. N,N-dimethyl-p-propenylaniline only appeared to form a complex with the catalyst. Low-molecularweight polymeric materials were prepared from anethole, isosafrole, and isoeugenol at ?45°C using the same catalyst while o-methoxypropenylbenzene formed oligomers. Isosafrole was recovered unchanged when treated with the boron trifluoride diethyl etherate initiator system at ?78°C in an attempt to increase the molecular weight of the polyisosafrole.     

Ortho-tellurated derivatives of some arylamines and imines

A range of novel bi-, tri- and multidentate organotellurium ligands containing Te and N donor atoms and their derivatives have been synthesised. The synthetic strategy involves telluration of orthochelating, monoanionic substrates derived from the following arylamines: N,N-dimethylbenzylamine, (S)-(-)-N,Ndimethyl-1-phenethylamine, N,N-dimethylnaphthylamine, (N,N-di-methylaminomethy l) ferrocene, tricarbony1(N, N-dimethylbenzenemethanamine) chromium and 2-(3-thienyl)-pyridine. In addition novel chiral hybrid Schiff base ligands have been prepared by the condensation reaction of bis(o-formylphenyl) telluride ando-butyltellurobenzaldehyde with (R)-(+)-l-phenethylamine and (1R, 2S)-(-)-norephedrine.     

Reaction of some coumarin and 4,6-diaryl-2H-pyran derivatives with secondary amines

The reaction of piperidine, morpholine, piperazine or dimethylamine with several coumarins, 3-bromocoumarin, 4,6-diaryl-2H-pyran-2-ones and 3-bromo-4,6-diaryl-2H-thiopyran-2-ones gave o-hydroxycinnamic acid amides, benzofurans, open-chain δ-oxoamides and thiophene derivatives, respectively.     

Synthesis of purinobenzodiazepine and purinobenzotriazocine derivatives,two new heterocyclic ring systems

The preparation of two new heterocyclic ring systems, purinobenzodiazepine and purinobenzotriazocine derivatives by the condensation of 8-aminotheophylline or 8-hydrazinotheophylline with o-carboxybenzaldehyde or o-carboxyacetophenone is described.     

Microwave assisted one pot synthesis of 2-ethylamino benzimidazole,benzoxazole and benzothiazole derivatives

A rapid and efficient one-pot method for the synthesis of 2-ethylamino benzimidazole, benzoxazole, and benzothiazole derivatives has been described. The reaction of o-phenylenediamines or o-aminophenols or 2-mercaptoanilines with EDC.HCl under microwave irradiation afforded the corresponding 2-ethylamino benzimidazole, benzoxazole and benzothiazole derivatives in excellent yields.     

Synthesis of some heterocyclic derivatives of 3,5-dinitro-o-toluic acid

The synthesis of a series of heterocyclic derivatives of 3,5-dinitro-o-toluic acid is described.     

Relative reactivity in the condensation of 2H-isoindole- and 2H-indazole-4,7-dione derivatives with o-aminobenzenethiol and its derivatives

The effects of substituents on the condensation of o-aminobenzenethiol derivatives with 2H-isoindole- and 2H-indazole-4,7-dione derivatives were studied by competitive reactions.     

Synthesis of 4-hydroxy- and 4-mercaptoquinazoline derivatives

The reaction of selenoesters with o-aminobenzamide and o-aminothiobenzamide derivatives led to the formation of 4-hydroxy- and 4-mercaptoquinazolines. Their structures were elucidated by means of elemental analyses and spectropic data (nmr and ms).     

Synthesis of imidazo[1,2-c] quinazoline and some of its methyl derivatives

The synthesis of imidazo [1,2-c] quinazoline was effected by manganese dioxide oxidation of the 5,6-dihydroimidazo [1,2-c] quinazoline which was prepared by treatment of 2-(o-nitro-phenyl)-1-hydroxyimidazole-3-oxide with zinc powder and formic acid. The synthesis of some methyl derivatives of this ring system are also described. Structural assignments for all of the products were made from spectral data.     

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4-benzothiazine,and 1,4-benzoxazine

Arylazo derivatives of quinoxaline (1,4-benzodiazine), 1,4-benzothiazine, and 1,4-benzoxazine have been prepared by condensation of hydrazidoyl halides with o-phenylenediamine, o-aminothiophenol, and o-aminophenol, respectively (Table I). This method seems to be more general than the approach using coupling of reactive diazonium salts with, e.g., 277–1,4-benzothiazine. Both the spectral data and the results of HMO calculations of bonding energies of the azo compounds obtained in this study indicate that they exist predominantly in the hydrazone tautomeric form.     

Mass spectrometry of imidazole-4(5)-carboxaldehyde and some 1-methyl and nitro derivatives

The mass spectra of imidazole-4(5)-carboxaldehyde, its two 1-methyl derivatives, 4(5)-nitroimidazole, 5(4)-nitroimidazole-4(5)-carboxaldehyde and 1-methyl-5-nitroimidazole-4-carboxaldehyde are presented and discussed in comparison with those of other imidazole-carboxaldehydes and nitroimidazoles earlier reported. The imidazole-carboxaldehydes and their 1-methyl derivatives exhibit the characteristic fragmentation of aromatic aldehydes, and differences between the isomers can be observed. The nitroimidazoles show the fragmentation typical of aromatic nitrocompounds. In the o-nitroimidazole-carboxaldehydes, the typical losses of aldehydes do not occur, but primary ortho effects between the formyl and nitro groups give rise to important fragmentation routes. In their 1-methyl derivatives, the presence of the methyl group adjacent to the nitro group originates additional double and secondary ortho effects. For some of these transformations, fragmentation mechanisms are proposed.     

Mass spectra of some triaryl derivatives of the group V elements,P, As,Sb and Bi

Triphenyl and tri-o-, m- and p-tolyl compounds of the elements P, As, Sb and Bi have been studied as well as tri-(2,6-dimethylphenyl)phosphine. The m- and p-tolyl isomers show very similar behaviour and differ significantly from the o-derivatives. The differences can be largely attributed to steric effects in the o-isomers. Major fragmentation pathways to Group V element (Mt)-containing ions involve Mt? C and C? H, and from the tolyl compounds C? C bond cleavages. Throughout this paper the symbol Mt is used to refer to the Group V element.     

Carbon-13 nuclear magnetic resonance study of a new ring-chain tautomerism of some pyridazine derivatives

The ¹³C NMR spectra of a number of pyridazine derivatives have been recorded in DMSO-d₆ solution and analysed. Examination of the most diagnostic resonances, with particular emphasis on those arising from the pyridazine ring system, enabled the ready establishment of the presence of a ring-chain tautomerism in 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylic acid, methyl 5-(o-aminophenylcarbamoyl)pyridazine-4-carboxylate, 5-(o-aminophenylcarbamoyl)-3,6,-dimethylpyridazine-4-carboxylic acid and 5-(2-amino-1,2-dicyanovinylenecarbamoyl)pyridazine-4-carboxylic acid. This gave rise to 3′,4′-dihydro-3′-oxospiro[pyridazine-5(2H),2′(1H)-quinoxaline]-4-carboxylic acid, methyl 3′,4′-dihydro-3′oxospiro[pyridazine-5(2H),2′(1′H)-quinoxaline]-4-carboxylate, 3′,4′-dihydro-3′-oxo-3,6-dimethylspiro[pyridazine-5(2H), 2′(1′H)-quinoxaline]-4-carboxylic acid and 5-oxo-2,3-dicyano-1,4,8,9-tetraazaspiro[5.5]undeca-2,7,10-triene-11-carboxylic acid, respectively.     

Synthesis of hexa-, tetra-, and dihydroxanthene derivatives from salicylaldehyde aminals

Salicylaldehyde aminals react with cyclohexanone upon heating to form tetrahydroxanthene derivatives. The structure of one of these derivatives,viz., 5,7-dichloro-4a-morpholino-1,2,3,4-tetrahydro-4aH-xanthene, was established by X-ray diffraction analysis. The scheme of the reaction was suggested, which involves cycloaddition of intermediateo-methylenequinone (from aminal) and enamine (from cyclohexanone). The reactions of salicylaldehyde aminals with enamines that formed from cyclohexanone can successively afford derivatives of hexahydroxanthene, tetrahydroxanthene, and dihydroxanthene. Procedures were developed for the synthesis of these compounds.N-Substituted 4a-amino-7-nitro-1,2,3,4-tetrahydro-4aH-xanthenes were also prepared by the reactions of dialkylammonium 2-formyl-4-nitrophenoxides with the above-mentioned enamines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 959–965, May, 1999.     

Oligomer-immobilizing ability of an electrodeposited aramid resin film in the electrooxidation of aniline derivatives and the functions of the resulting films

An aramid resin, poly(p-phenylene terephthalamide) (PPTA), was electrodeposited on an indium-tin oxide electrode as a mechanically stable film from a dimethyl sulfoxide solution. Two aniline derivatives, o-phenylenediamine and o-aminophenol, were electrooxidized from H₂SO₄ aqueous solutions using the PPTA film-coated electrode. The PPTA film was permeable to the aniline derivatives, and the derivatives were electrooxidized on the electrode surface. When the derivatives were electrooxidized, the film immobilized the corresponding oligomer species as well as the polymers plain (o-phenylenediamine) (PoPD) and poly(o-aminophenol) (PoAP), and the deposited amount of the polymers was increased by the PPTA film. The immobilized amount of PoAP was greater than that of PoPD because of the 1,4-substituted structure of PoAP. In the PPTA film, both PoPD and PoAP were electronically stabilized, and they became durable against oxidative degradation.     

Photocyclization reactions. Part 8. Synthesis of 2‐quinolone,quinoline and coumarin derivatives using trans‐cis isomerization by photoreaction

2‐Quinolone 2 , quinoline 3 , coumarin (2H‐1‐benzopyran‐ 2 ‐one) 5 , and 2H‐1‐benzopyran hemiacetal 6 were synthesized by photocyclization reaction of traans‐o‐aminocinnamoyl derivatives trans‐ 1 and trans‐o‐hydroxycinnamoyl derivatives trans‐ 4 . The reaction proceeds through trans‐cis isomerization followed by intramolecular cyclization.     

The synthesis of benzophenothiazine derivatives

Summary The reaction of substituted 1,4-naphthoquinones with 2-aminothiophenol ando-aminoheterocyclic thiones in acidic condition afforded benzophenothiazin-5-one and azabenzophenothiazin-5-one derivatives, respectively.

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Die Synthese von Benzophenothiazin-Derivaten

Zusammenfassung Die Reaktion von substituierten 1,4-Naphthochinonen mit 2-Aminophenol bzw.o-aminoheterocyclischen Thionen führte unter sauren Bedingungen zu Benzophenothiazin-5-onen bzw. Azabenzophenothiazin-5-onen.

     

Isoindole derivatives from o-diacylbenzenes and aromatic amines

o-Acetylbenzophenone produced yellow 1,2-diaryl-3-(aryliminomethyl)isoindole by the reaction with aromatic amines in the absence of acid. On the reaction of o-diacetylbenzene under the similar condition, three types of yellow products were obtained. The structures of these isoindole derivatives were determined and their formation mechanism was proposed.