Pyrimidines

In the condensation of benzalbisurea with 1-methyl-3,5-diaminopyrazole the pyrimidine ring closes through the amino group of pyrazole in the 5 position to give 1-methyl-4-phenyl-3-benzalamino-6-oxo-4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidine. The latter is converted to 1-methyl-4-phenyl-3-amino-6-oxo-6,7-dihydropyrazolo [3,4-d]pyrimidine by dehydrogenation and subsequent hydrolysis of the benzylidene group.     

Synthesis and liquid-crystal properties of aryl esters of p-(5-alkyl-2-pyrimidinyl)benzoic acids

Aryl esters of p-(5-alkyl-2-pyriraidinyl)benzoic and p-(5-alkyl-2-pyrimidinyl)-benzoyloxybenzoic acids, which displayed nematic properties with broad ranges of the existence of a meso phase, particularly in the case of the diesters (up to 140–170C), were obtained. It is shown that the presence of a 2-phenyl group in the pyrimidine ring favors the development of a liquid-crystal state as compared with 5-phenylpyrimidines.DeceasedTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1636–1639, December, 1988     

Pyrimidines

3-Arylbenzo[f]quinazolines were obtained by reaction in acetic or propionic acid of -naphthylamine, ammonia, and aromatic aldehydes containing an NR₂ or OH group. A mechanism is proposed for the formation of monoarylbenzo[f]quinazolines from the corresponding intermediate 1,3-diaryldihydrobenzo [f] quinazolines by acid cleavage of the C-aryl bond in the 1 position. This mechanism was confirmed experimentally by establishment of the fact of cleavage of 1,3-bis (p-methoxyphenyl)-1,2-dihydrobenzo[f] quinazoline when the acidity of the medium is increased; 3-(p-methoxyphenyl) benzo [f] quinazoline and anisole were obtained in the reaction products. Condensation in the presence of formic acid gave -arylidene-N-formyl--naphthylamines rather than arylbenzo [f] quinazolines.See [1] for communication LXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1265–1271, September, 1978.     

Reactions of Pyrrole-1- and Pyrrole-2-carbodithioates with Activated Acetylenes

Pyrrole-1- and pyrrole-2-carbodithioates react with activated alkenes (KOH-DMSO, room temperature) along the nucleophilic addition mechanism regio- and stereospecifically to afford pyrrole-1-and pyrrole-2-carbodithioethenes. The adducts of pyrrole-2-carbodithioates under the reaction conditions undergo intramolecular cyclization into pyrrolothiazoles derivatives.     

C?H···N and C?H···O intramolecular hydrogen bonding effects in the 1H, 13C and 15 N NMR spectra of the configurational isomers of 1‐vinylpyrrole‐2‐carbaldehyde oxime substantiated by DFT calculations

According to the ¹H, ¹³C and ¹⁵N NMR spectroscopic data and DFT calculations, the E‐isomer of 1‐vinylpyrrole‐2‐carbaldehyde adopts preferable conformation with the anti‐orientation of the vinyl group relative to the carbaldehyde oxime group and with the syn‐arrangement of the carbaldehyde oxime group with reference to the pyrrole ring. This conformation is stabilized by the C? H···N intramolecular hydrogen bond between the α‐hydrogen of the vinyl group and the oxime group nitrogen, which causes a pronounced high‐frequency shift of the α‐hydrogen signal in ¹H NMR (～0.5 ppm) and an increase in the corresponding one‐bond ¹³C–¹H coupling constant (ca 4 Hz). In the Z‐isomer, the carbaldehyde oxime group turns to the anti‐position with respect to the pyrrole ring. The C? H···O intramolecular hydrogen bond between the H‐3 hydrogen of the pyrrole ring and the oxime group oxygen is realized in this case. Due to such hydrogen bonding, the H‐3 hydrogen resonance is shifted to a higher frequency by about 1 ppm and the one‐bond ¹³C–¹H coupling constant for this proton increases by ～5 Hz. Copyright © 2008 John Wiley & Sons, Ltd.     

Nanoporous crosslinked macrocyclic polyethers based on diethylene glycol divinyl ether and their superbase complexes with KOH

Nanoporous (11–12 nm) crosslinked macrocyclic polyethers with vinyloxy and hydroxyl groups have been synthesized by the free-radical polymerization of diethylene glycol divinyl ether (AIBN, 80°C, i-octane), followed by acidic hydrolysis. It has been shown that the polymers react with KOH to form insoluble superbase complexes and alcoholates capable of catalyzing vinylation of ethylene glycol by acetylene.     

Pyrroles from ketoximes and acetylene. 41. Some reactions of 1-vinyl-2-(2-furyl)- and-(2-thienyl)pyrroles

We have studied the reaction of 1-vinyl-2-(2-furyl)- and -(2-thienyl)pyrroles with trifluoroacetic anhydride, with hydrogen in the presence of catalysts (Raney nickel, palladium black, palladous chloride), with propargyl alcohol in electrophilic conditions [catalysis by perfluorobutyric acid in the system azoisobutyrodinitrile (AIBN)-CCl₄), and with alkane thiols with AIBN initiation. The products are novel substituted hetarylpyrroles.See [1] for Communication 40.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 337–342, March, 1991.     

Synthesis and Liquid Crystal Properties of Aryl Esters of Laterally Substituted 5-Pyrimidinecarboxylic Acids

(p-R-phenyl)-4-methyl-, 4-methoxy-, and 4-hydroxy-5-pyrimidinecarboxylates have been synthesized and their liquid crystal properties examined. Compounds containing methyl and methoxy groups in the lateral position of the molecule are nematic liquid crystals with a mesophase range of 30-50°C, but the 4-hydroxy derivatives are smectic liquid crystals. With variants of the substituents in a series of (p-R-phenyl)-4-substituted 5-pyrimidinecarboxylates the mp of individual representatives were successfully reduced by 50°C in comparison with the 4-unsubstituted analogs and the range of the mesomorphic state was extended to 190°C.