Showing papers by "Alan R. Katritzky published in 1991"
TL;DR: In this paper, the Mannich reaction was extended to a variety of vinylogous systems including enamines, enol ethers, and nitrones using benzotriazolyl residues.
220 citations
TL;DR: In this article, semi-pirational AM1 quantum-chemical calculations of the principal tautomers of cytosine, thymine, uracil, 1-methylcytosine and guanine were carried out for isolated molecules, and for the same molecules in a polarizable dielectric medium with the relative permittivity of water, using the self-consistent reaction field method.
Abstract: Semiempirical AM1 quantum-chemical calculations of the principal tautomers of cytosine, thymine, uracil, 1-methylcytosine, 1-methylthymine, 1-methyluracil, adenine, and guanine were carried out for the isolated molecules, and for the same molecules in a polarizable dielectric medium with the relative permittivity of water, using the self-consistent reaction field method. In almost all cases, the same tautomer is predicted as most stable regardless of the method used and environment applied. However, the calculations imply significant quantitative differences in the relative stabilities of the tautomers in different media, which need to be taken account of in the nucleic acid base pairing/mispairing probability estimations based on quantum-chemical data
144 citations
TL;DR: In this article, a review dealing mainly with the prototropic side chain tautomerism of heteroaromatic compounds is presented, with particular reference made to molecular orbital calculations of equilibrium constants.
Abstract: This review deals mainly with the prototropic side chain tautomerism of heteroaromatic compounds. Particular reference is made to molecular orbital calculations of equilibrium constants
121 citations
TL;DR: N-(1-Benzotriazol-1-ylalkyl)amides 2, easily prepared from an amide and an aldehyde with benzotrizole, react smoothly with CH acids under mild conditions to give the α-amidoalkylation products in good yields.
Abstract: N-(1-Benzotriazol-1-ylalkyl)amides 2, easily prepared from an amide and an aldehyde with benzotriazole, react smoothly with CH acids under mild conditions to give the α-amidoalkylation products in good yields. Benzotriazole aminals also react with CH acids in the presence of methyl iodide
58 citations
42 citations
TL;DR: In this paper, the aquathermolysis reactivity of nine organic sulfur compounds was investigated to determine their potential to generate hydrogen sulfide during the cyclic steam stimulation process to recover Cold Lake bitumen.
Abstract: The aquathermolysis reactivity of nine organic sulfur compounds was investigated to determine their potential to generate hydrogen sulfide during the cyclic steam stimulation process to recover Cold Lake bitumen. Dioctyl sulfide, 1-decanethiol, didecyl disulfide, 1-naphthalenethiol, 1,1'-dinaphthyl sulfide, 1,1'-dinaphthyl disulfide, 1-naphthyl 1-octyl sulfide, tetrahydrothiophene, and thiophene were selected as model compounds and subjected to neutral, basic, and acidic aquath-ermolysis conditions at 250 and 300 o C. Thiols, and thiols formed by cleavage of sulfides and disulfides were found to be the source of H 2 S evolution. Aliphatic sulfides, in addition to their usual C-S bond cleavage, showed α,β C-C bond cleavage
36 citations
34 citations
30 citations
TL;DR: In this article, Grignard reagents replace the benzotriazole residues of some of the compounds thus obtained to give the corresponding methyl ethers, and the carbanion affords substitution products with various electrophiles.
Abstract: 1 -Methoxymethylbenzotriazole undergoes lithiation at the methylene group and the carbanion affords substitution products with various electrophiles. Grignard reagents replace the benzotriazole residues of some of the compounds thus obtained to give the corresponding methyl ethers.
25 citations
22 citations
TL;DR: In this article, the results of the quantum-chemical calculations of radical formation energies from simple organic molecules in gas phase and in dielectric polarizable medium using AM1 and MNDO Hamiltonians with original and recent parametrizations in combination with self-consistent reaction field procedure are in satisfactory quantitative agreement with experimental data.
Abstract: The results of the quantum-chemical calculations of radical formation energies from simple organic molecules in gas phase and in dielectric polarizable medium using AM1 and MNDO Hamiltonians with original MNDO and recent MNDO-PM3 parametrizations in combination with self-consistent reaction field procedure are in satisfactory quantitative agreement with experimental data. A solvent-assisted merostabilization effect is observed only in the case of captodative radicals
TL;DR: N]-(1-Benzotriazol-1-yl)alkyl]amides 1 react readily with a variety of thiols (both aliphatic and aromatic) and sodium sulfide under mild conditions to give N-acylhemithioaminals in good yields as mentioned in this paper.
Abstract: N-[(1-Benzotriazol-1-yl)alkyl]amides 1 react readily with a variety of thiols (both aliphatic and aromatic) and sodium sulfide under mild conditions to give N-acylhemithioaminals in good yields
TL;DR: In this article, 4-(benzotriazol-1-ylmethyl)-N,N-dimethylaniline (1b) can be substituted at the CH 2 link via lithiation.
Abstract: 4-(Benzotriazol-1-ylmethyl)-N,N-dimethylaniline (1b) can be substituted at the CH 2 link via lithiation. Both the parent and substituted derivatives react with a variety of electron-rich benzenoid and heteroaromatic compounds in a novel approach to leuco dyes. Other 4-(benzotriazol-1-ylmethyl)anilines react similarly
TL;DR: In this paper, 1H-Benzotriazole reacts with an aldehyde and thiourea or an N-substituted thienourea to form Mannich-type condensation products which on treatment with sodium borohydride or benzylmagnesium chloride yield N,N′-disubstitized thienoupine or carbodiimides, respectively.
Abstract: 1H-Benzotriazole reacts with an aldehyde and thiourea or an N-substituted thiourea to form Mannich-type condensation products which on treatment with sodium borohydride or benzylmagnesium chloride yield N,N′-disubstituted thioureas or carbodiimides, respectively.
TL;DR: In this paper, the authors show that hindered alkyl aldehydes react with benzotriazole and ammonia in dry ethanol or methanol to yield the corresponding bis[1-(benzotriaxol-1-yl)-N-alkylidenealkylamines.
Abstract: Hindered alkyl aldehydes react with benzotriazole and ammonia in dry ethanol or methanol to yield the corresponding bis[1-(benzotriazol-1-yl)alkyl]amines 2. The reaction of aryl aldehydes, however, yields 1-(benzotriazol-1-yl)-N-alkylidenealkylamines 3. The reactions of adducts 2 and 3 with lithium aluminum hydride furnishes dialkyl- and dibenzylamine derivatives 4. Although the reactions of 2 and 3 with organometallic reagents are not as general, in several cases the reactions of amines 2 with Grignard reagents yield 1-alkyl or aryl substituted N-alkylidenealkylamines 5
TL;DR: Crossover experiments demonstrate that the title rearrangement processes are intermolecular as discussed by the authors, which is consistent with the results of our experiments, and they also support our results.
Abstract: Crossover experiments demonstrate that the title rearrangement processes are intermolecular.
TL;DR: In this paper, a new general method for the transformation of ketones into their enol ethers in good yield was developed via elimination of benzotriazole from N-(1-alkoxyalkyl)benzotriazy intermediates.
Abstract: A new general method for the transformation of ketones into their enol ethers in good yield is developed via elimination of benzotriazole from N-(1-alkoxyalkyl)benzotriazole intermediates
TL;DR: In this paper, N-Arylmethylene[(benzotriazol-1-yl)arylmethyl]amines are prepared by the reaction of arylaldehydes, benzotitriazole, and ammonia in dry ethanol.
Abstract: N-Arylmethylene[(benzotriazol-1-yl)arylmethyl]amines 1 are prepared by the reaction of arylaldehydes, benzotriazole, and ammonia in dry ethanol. Deprotonation of these imines with butyllithium yields N-lithiated azomethine ylides 2 which readily undergo 1,3-dipolar cycloaddition with a large range of dipolarophiles. The cyclisations are regiospecific and generally exhibit high stereoselectivity
TL;DR: In this paper, 1.1 H and 13 C NMR studies were carried out on 1-ethenylnaphthalene, 2-ethelnaphthracene, 9-ethylphenanthrene, 1-ethyl pyrene, and 1-etheylperylene, with the aid of 2D COSY, 2D HETCOR and 2D COLOC.
Abstract: 1 H and 13 C NMR studies were carried out on 1-ethenylnaphthalene, 2-ethenylnaphthalene, 9-ethenylanthracene, 9-ethenylphenanthrene, 1-ethenylpyrene and 1-ethenylperylene. Assignments of proton and carbon resonances were made with the aid of 2D COSY, 2D HETCOR, 2D COLOC, 2D COLOCS, 3 J(H,C) INAPT, and NOE difference spectral techniques
TL;DR: Preparations of S-mono- and unsymmetrical S,S-di-substituted derivatives of 1,3,4-thiadiazole-2,5-dithione are described in this paper.
TL;DR: In this paper, the concentrations of heteroaromatics which inhibit growth of Tetrahymena pyriformis were tested for correlation with twelve measures of aromaticity for these compounds together with log P and the molecular connectivity.
Abstract: The concentrations of heteroaromatics which inhibit growth of “Tetrahymena pyriformis” are tested for correlation with twelve measures of aromaticity for these compounds together with log P and the molecular connectivity. A two principal component (PC) model accounts for 65% of the total variance and demonstrates the significance of scales of magnetic aromaticity in general and of χM in particular, of log P and of molecular connectivity. PLS treatment using the three descriptors I′x, χM and log P explains 89% of the variance: a single parameter correlation with χM is almost as successful.
The potential for the present method to predict toxicities of heterocycles is indicated.
TL;DR: In this article, arylideneaminoalkylamines are prepared by the reaction of 1-(benzotriazol-1-yl)-N-triphenylphosphorylidenemethylamine (Betmip) with lithium amides and treatment of the resulting intermediates with aryls aldehydes.
Abstract: α-(Arylideneamino)alkylamines 4 are prepared in high yields by the reaction of 1-(benzotriazol-1-yl)-N-triphenylphosphorylidenemethylamine (betmip) 2 with lithium amides and treatment of the resulting intermediates 3 with aryl aldehydes. Key words: benzotriazole, lithium amides, aryl aldehydes.
TL;DR: In this paper, the thermal isomerization of N-[α-(alkylthio)alkyl]- and N-[β]-benzotriazoles was investigated under N 2 atmospheres in toluene, xylene, MeOH, or EtOH, in the presence of acid catalysts and (ii) in the absence of solvent.
Abstract: The thermal isomerizations of N-[α-(alkylthio)alkyl]- and N-[α-(arylthio)alkyl]benzotriazoles have been investigated under N2 atmospheres (i) in toluene, xylene, MeOH, or EtOH, in the presence of acid catalysts and (ii) in the absence of solvent. The sulfide isomerization rates depend on the number of H-atoms carried by the C-atom attached to the N-atom of the benzotriazole: tertiary (no hydrogen) > secondary (1 hydrogen) > primary (2 hydrogens). The results support an isomenzation mechanism involving a heterolytic NC bond cleavage with formation of sulfonium/carbonium and benzotriazolate ions.
TL;DR: In this paper, the formylation par MeOCHCl 2 /TiCl 4 dans CS 2 for polystyrene, poly(1-vinylnaphtalene), poly(9vinylphenanthrene) and poly(poly(1vinylpyrene) is presented.
Abstract: La formylation par MeOCHCl 2 /TiCl 4 dans CS 2 du polystyrene, du poly(1-vinylnaphtalene), du poly(9-vinylphenanthrene) et du poly(1-vinylpyrene) donne avec de bons rendements des polymeres lineaires de degre de substitution eleve, sauf pour le polystyrene ou on observe une reticulation plus importante. Cette methode est applicable aux polymeres vinyliques lineaires ou reticules portant des groupes lateraux aromatiques. Le degre de formylation des polymeres portant des cycles aromatiques condenses est controlable en variant les proportions des reactifs
TL;DR: In this article, the synthesis of 1,4-diazabicyclo[2.2]octane and piperazine derivatives of potential interest for second-order NL optical activity is described.
TL;DR: Six organic compounds were spray-coated onto surface acoustic wave devices and exposed to vapors of acetone, diethyl ether, dichloromethane, chlorobenzene, benzene, and acetonitrile, and different patterns of response to the six vapors were observed for each of the coatings.