Tautomeric equilibrium of 1-β-D-ribofuranosyl-2-keto-4-(n-methoxyamino)pyrimidine

The 1-β-D-ribofuranosides of 2-keto-4-(N-methoxyamino)pyrimidine, 2-keto-4-(N-methyl-N-methoxyamino)pyrimidine, and 2-keto-3-methyl-4-(N-methoxyamino)pyrimidine were synthesized, and their pK_a values were determined by spectrophotometry. The pK_a values of the compounds are evidence that the tautomeric equilibrium between the oxime and hydroxyamine forms of 1-β-D-ribofuranosyl-2-keto-4-(N-methoxyamino)pyrimidine in aqueous solutions is shifted to favor the oxime form (K_T?25).     

2,5-Dimethyl-4-(p-aminobenzyl)pyridine in the synthesis of substituted quinolines,pyridoindazoles, and isoquinolinoquinolines

2,5-Dimethyl-4-pyridyl(6-quinolyl)methane was obtained from 2,5-dimethyl-4-(p-aminobenzyl)pyridine via the Skraup reaction. The product was nitrated to 2,5-dimethyl-4-pyridyl (5-nitro-6-quinolyl)methane, which was reduced to 2,5-dimethyl-4-pyridyl (5-amino-6-quinolyl)methane. It was established that the diazo compound formed from this amino derivative is converted to 1H,3-(2,5-dimethyl-4-pyridyl)-pyrido [2,3-g]indazole as a result of intramolecular cyclization. 9-Methyliso-quinolino [7,6-f]quinoline was obtained by catalytic dehydrocyclization of 2,5-dimethyl-4-pyridyl (6-quinolyl)methane. 2,5-Dimethyl-4-pyridyl(5-nitro-6-quinolyl)methane has chemochromic properties.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 677–680, May, 1980.     

Nitration of some 2, 5-disubstituted 4-phenylpyridin es

2,5-Dimethyl-4-phenylpyridine is nitrated in the para position of the phenyl ring. Further nitration of the resulting nitro compound gives a mixture of isomeric dinitro derivatives. In the case of 4-phenylisocinchomeronic acid the nitro group enters the meta position of the phenyl ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii. No. 3, pp. 365–368, March, 1976.     

Synthesis of spiro[9,10-dihydro-10-sila-2-azaanthracene-9,1′-cyclopropanes

The Z- and E-isomers of 9,14dihydro-10,10-&-methyl-2-trimethylsilyl(2phenyl-3 fornryl)spiro[IO-sila-2-azaanthracene-9,1 -cyclopropane] have been obtained by heating 9-diazo-9,10-dihydro-10,10-dimethyl-10-sila-2azaanthracene with trimethylvinylsilane and with cinnanuaidehyde.     

Mass spectroscopic study of 2,5-dimethyl-4-benzoyl- and 2,5-dimethyl-4-benzylpyridine derivatives

The dissociative ionization of sixteen 4-benzoyl- and 4-benzylpyridine derivatives and their deuteroanalogs has been studied. An ortho effect, due to the benzoyl and benzyl radicals in the methyl group in the 5-position of the pyridine ring, has been detected. It has also been established that fragmentation of 4-benzoylpyridines substituted with a nitro group in the benzene ring leads to [M-OH]⁺ ions, due to the ortho effect, whereas fragmentation of 4-benzylpyridines leads to [M-C₆H₅R]⁺ ions. The probability of a given process depends on the position and nature of any substituent in the benzene ring; this makes it possible to identify different isomers in a given series of compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 810–816, June, 1987.     

Reaction of pyrido[1,2-a]benzimidazole and tetrahydropyrido[1,2-a]benzimidazole with acetylenedicarboxylic ester

Previously unknown polynuclear condensed systems with bridgehead nitrogen atoms have been obtained by treating acetylenedicarboxylic ester with pyrido[1,2-a]-benzimidazole and tetrahydropyrido[1,2-a]benzimidazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 239–241, February, 1986.     

Synthesis of 3-dimethylphenylsilyl-substituted pyrido[1,2-a]benzimidazoles

Reductive cyclization of 1-(2,4-dinitrophenyl)-3-methyl-4-dimetkylphenyisililpyridinium chloride by the action of phenylkydrazine or hydrogen in the presence of Pd/C gave, for the first time, 7-nitro (amino)-3 dimethylphenylsilylpyrido[l, 2-affienzimidazoles.Russian University of the Friendship of Nations, Moscow, 117923. Translated from Khimiya Geterots ikl icheskikh Soedinenii, No, 3, pp. 338–341, March, 1996. Original article submitted November 27, 1995.