Boron fluorides of cis- and trans-2-aryl-3-aroylaziridines

The reaction of boron trifluoride etherate with cis- and trans-2-aryl-3-aroylaziridines yields the respective complexes in high yield. According to PMR spectral data the methyl group of boron trifluoride trans-1-methyl-3-aroylaziridines is located in syn-position, and in the cis-aziridine complexes in anti-position, to the carbonyl group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1047–1049, August, 1987.     

Reaction of 1-alkyl-2-aryl-3-(2-methyl-2,3-epoxypropionyl)aziridines with boron trifluoride etherate in methanol

The reaction of boron trifluoride etherate in methanol with trans-1-methyl(ethyl)-or cis-1-cyclohexyl-2-aryl-3-(2-methyl-2,3-epoxypropionyl)aziridines leads to the formation of the corresponding boron fluoride complexes on the nitrogen atom of the aziridine ring. Reaction with trans-1-cyclohexyl-2-phenyl-3-(2-methyl-2,3-epoxypropionyl)aziridines occurs with stereospecific opening of the aziridine ring to give diastereomeric 2-methyl-5-methoxy-5-phenyl-4-cyclohexylamino-1,2-epoxypen-tan-3-ones, as well as products from the opening of the epoxide and aziridine rings — tetrahydrofuranones and tetrahydropyranones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 596–600, May, 1986.     

Chemistry of indole

The condensation of salts of 1-methyl-2-aminoindole with aldehydes in excess alkali gives Schiff bases, while salts of 1-methyl-3-arylidene-2-iminoindolines are obtained in the absence of alkali. The latter may give 12-aryl-5,7-dimethylindolo[2,3-b]--carbolines (I) on reaction with excess 1-methyl-2-aminoindole. Dihydro compounds (II) are formed as intermediates.See [1] for communication XXXI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1368–1373, October, 1972.     

Synthesis and stereochemistry of 2, 2-dimethyl-5-aryl-4-benzoyl-1,3-dioxolanes

The reaction of 3-aryl-2-benzoyloxiranes with acetone in the presence of catalytic amounts of boron trifluoride etherate leads to the formation of mixtures of cis and trans isomers (3070) of 2,2-dimethyl-5-aryl-4-benzoyl-1,3-dioxolanes, the structures and stereochemistry of which were established on the basis of data from their PMR spectra, measurement of the Overhauser nuclear effect, and some chemical transformations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 888–891, July, 1979.     

Synthesis,stereochemistry, and isomeric transformations of 4-aryl-5-aroyl-2-methylthio-2-imidazolines

The corresponding 4-aryl-5-aroyl-2-methylthio-2-imidazolines were obtained by the reaction of complexes of cis- and trans-3-aroylaziridines and boron trifluoride with methyl thiocyanate. It is shown on the basis of spectral data that the aziridine ring is opened regiospecifically at the C(₂) atom and stereospecifically with inversion of the configuration.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1484–1488, November, 1988.     

Boron Difluoride β-Diketonates: III. Boron Difluoride 3-Organylpenta-2,4-dionates

Boron difluoride 3-methyl-, 3-ethyl-, 3-propyl-, 3-isopropyl-, and 3-phenylacetylacetonates were synthesized by acylation of ketones with acetic anhydride, chelation of -organyl--diketones, and reaction of acetylacetone with isopropanol in the presence of boron trifluoride. The resulting chelates were characterized by ¹H NMR, IR, and UV spectroscopy.     

Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.     

Synthesis,halogenation, and nitration of 6-methyl-3-phenyl-2-pyrone derivatives

Simple methods for the synthesis of 3-aryl-6-methyl-2-pyrones and 3-aryl-5-carbalkoxy-6-methyl-2-pyrones by the reaction of ethyl -formylarylacetates with acetone and acetoacetic acid esters, respectively, are proposed. Some electrophilic substitution reactions of 6-methyl-3-phenyl-2-pyrone and 5-carbethoxy-6-methyl-3-phenyl-2-pyrone were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1477–1480, November, 1985.     

Synthesis of cis-3,4-diarylpiperidines and cis-3,4-diaryltetrahydropyrans

Substituted cis-3,4-diarylpiperidines and cis-3,4-diaryltetrahydropyrans are synthesized in modest overall yields starting from 4-aryl-1,2,5,6-tetrahydropyridines and 4-aryl-1,2,5,6-tetrahydropyrans via the following sequence: (1) pinacol-type ring contraction having the combination of m-chloroperoxybenzoic acid and boron trifluoride etherate, (2) Grignard addition with arylmagnesium bromide reagents and followed by boron trifluoride etherate-mediated intramolecular ring-expanded rearrangement, and (3) hydrogenation with hydrogen on 10% palladium-activated carbon. A facile synthesis of 3,4-diarylpyridines was also described by base-induced aromatization.     

含有螺环己烷结构的稠环斯德酮的合成

3-(3-芳基-3-羟基丙基)斯德酮在三氟化硼乙醚的催化作用下可以与环己酮发生类似于Oxa-Pictet-Spengler反应的成环反应,生成带有螺环己烷结构的稠环斯德酮.     

Synthesis and condensation reactions of the boron difluoride complex with 3-acetyl-4-hydroxy-1-methyl-2-quinolone

A reaction of 3-acetyl-4-hydroxy-1-methyl-2-quinolone with boron trifluoride etherate gave its boron difluoride complex. Condensation of this complex with various carbonyl compounds afforded new 2-quinolone derivatives (polymethine and styryl dyes) that intensely absorb in the visible region of the spectrum and show effective fluorescence. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1701–1706, August, 2008.     

Cyclization of N1-aryl-N3-acetyl-p-nitrobenzamidrazones to substituted 1,2,4-triazoles

The reaction of -acetamido-p-nitroacetophenone with benzenediazonium salts gave N¹-aryl-N³-acetyl-p-nitrobenzamidrazones, which are cyclized to 5-methyl-1-aryl-3-(p-nitrobenzoyl)-1,2,4-triazoles. The latter are quaternized at the nitrogen atom in the 4 position.Translated from Khimiya Geterotsikli-cheskikh Soedinenii, No. 4, pp. 537–539, April, 1977.     

Synthesis of 1,2,4- and 1,3,4-oxadiazoles from 1-aryl-5-methyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole-4-carbonyl chlorides

5-Substituted 2-(1-aryl-5-methyl-1H-1,2,3-triazol-4-yl)-1,3,4-oxadiazoles were synthesized by reaction of 1-aryl-5-methyl-1H-1,2,3-triazole-4-carbonyl chlorides with the corresponding 5-substituted 1H-tetrazoles. 5-Methyl-1-phenyl-1H-1,2,3-triazole-4-carbonyl chloride reacted with N′-hydroxybenzimidamides to give 3-aryl-5-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-1,2,4-oxadiazoles. Reactions of 4-(5-methyl-1H-1,2,3-triazol-1-yl)benzoic acid with N′-hydroxybenzimidamides resulted in the formation of 3-aryl-5-[4-(5-methyl-1H-1,2,3-triazol-1-yl)phenyl]-1,2,4-oxadiazoles.     

Synthesis and properties of ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-3-carboxylates

Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3-carboxylates reacted with phenylhydrazine to give the corresponding hydrazones, ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1H-pyrazole-3-carboxylates, which were converted to ethyl 1′-aryl-4-formyl-5′-methyl-1-phenyl-1H,1′H-3,4′-bipyrazole-3′-carboxylates by treatment with the Vilsmeier–Haack reagent. No indole derivatives were formed from the same hydrazones under the Fischer reaction conditions, but cyclization to 2-aryl-3,4-dimethyl-6-phenyl-2,6-dihydro-7H-pyrazolo[3,4-d]pyridazin-7-ones was observed.     

Researches on substituted arylamides of dithiocarboxylic acids

The following compounds hitherto undescribed in the literature, are prepared: ethyl esters of arylamides of cyanomonothiomalonic acid, with electronegative substituents in the phenyl groups, aryl amides of cyanoacetic acid, and nitriles of substituted anilides of arylazothiomalonic acid. Heating arylamides of cyanoacetic acid with -bromoacetophenone in absolute alcohol gives quaternary salts of 2-cyanomethyl-3-aryl-4-phenylthiazoles and their methylene bases. Reaction of the quarternary salts of 2-cyanomethyl-3-aryl-4-phenylthiazoles with substituted phenyldiazonium salts gives a number of 2-cyanoarylazomethylene-3-aryl-4-phenylthiazoles.     

BF3-promoted synthesis of spiroindenyl heterocycles

An easy and straightforward synthesis of spiroindenyl heterocycles by the repeated treatment of boron trifluoride etherate (BF₃-OEt₂) is reported. The overall transformation from ketones 1 to spiro-fused indenes 3 proceeds via Wittig olefination, deconjugation, Grignard addition, and intramolecular electrophilic cyclization in moderate yields. It presents a novel rearrangement reaction catalyzed by boron trifluoride etherate and broadens the scope of application.     

New synthesis of 3-arylpyrrolines

We present an easy and straightforward synthesis of 3-arylpyrrolines 4a-g by repeated treatment of 4-aryl-1,2,5,6-tetrahydropyridines 2a-g with m-chloroperoxybenzoic acid (MCPBA) and boron trifluoride etherate (BF₃-OEt₂). The transformation proceeds via epoxidation, ring contraction, Baeyer-Villiger oxidation and elimination reaction and affords 3-arylpyrrolines 4a-g with 61-70% yield. This facile strategy was also used to synthesize racemic baclofen (6).     

Highly regioselective direct halogenation: a simple and efficient method for preparing 4-halomethyl-5-methyl-2-aryl-1,3-thiazoles

An unprecedented C4-methyl regioselective halogenation of 4,5-dimethyl-2-aryl-1,3-thiazoles (1) has been accomplished. The reaction of compound 1 with N-chlorosuccinimide and N-bromosuccinimide under mild conditions provides an efficient and operationally simple method for obtaining 4-chloromethyl-5-methyl-2-aryl-1,3-thiazoles (2) and 4-bromomethyl-5-methyl-2-aryl-1,3-thiazoles (3), respectively, in good yields without the formation of 4-methyl-5-halomethyl regioisomers.     

Stereochemistry of the synthesis of 1,2,3,4-tetrahydrocinnolines from aryldiazenium salts and olefins

It follows from the PMR spectra that the reaction of 1-methyl-, 1-phenyl-, 1-ethyl-,1-phenyl-, and 1,1-diphenyldiazenium salts with cis- and trans-d-styrenes, which leads to the corresponding 3-d-4-phenyl-1,2,3,4-tetrahydrocinnolines, takes place with retention of the configuration in the starting styrenes. It is therefore proposed that this reaction be regarded as a special case of [4⁺_s + 2_s]-cycloaddition.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1658–1661, December, 1977.     

Synthesis,stereochemistry, and isomeric transformations of cis- and trans-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines

The corresponding trans- and cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines were obtained from complexes of cis- and trans-1-methyl-2-aryl-3-aroylaziridines with BF₃ by heating with acetonitrile. The reaction proceeds with inversion of the configuration of the starting 3-aroylaziridines. In the presence of bases the complexes of cis-1,2-dimethyl-4-aryl-5-aroyl-2-imidazolines readily undergo isomerization to the corresponding trans analogs. The structures of the products were established on the basis of the IR, PMR, and mass spectra and the results of elementary analysis. The configurations of the compounds were determined by means of the Overhauser nuclear effect.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 952–957, July, 1981.