V. L. Rusinov

Ethyl cyanoacetate as 1,3-bifunctional reagent in the pyrimidine to pyridine ring transformations

Abstract By using of the double-labelled C * N * - CH 2 - COOEt compound it has been proved that transformation of 6-nitro-1,2,4-triazolo[1,5-a]pyrimidine into 2-triazolylamino-3-carbethoxy-5-nitropyridine proceeds with incorporation of the C-C-N fragment of ethyl cyanoacetate into the pyridine ring.

Preparation of Pyridyl-substituted Monoazatriphenylenes

Azatriphenylene derivatives are of considerable interest due to their promising photophysical and coordinating properties [1] and to their presence in the composition of natural compounds [2, 3]. Azatriphenylenes are important in inorganic biochemistry thanks to their use as intercalating ligands [4, 5]. In addition, azatriphenylenes have shown promise as luminescent chemosensors of organic anions and nitroaromatic compounds [6]. The most frequently used method for preparing azatriphenylenes is the Skraup synthesis [7, 8] which demands the use of forcing conditions. Contemporary synthetic methods broadly use a cycloaddition reaction of hard to obtain alkenes or arylacetylenes with aromatic substrates catalyzed by transition metal salts [9, 10]. Finally, the cyclocondensation of phenanthrenequinone with hydrazones of (hetero)aromatic carboxylic acid amides leads to the corresponding aryl[11, 12] and hetaryl-substituted [13] triazatriphenylenes. In this report, we propose an efficient method for the synthesis of cycloalkene-annelated derivatives of monoazatriphenylenes based on an aza-Diels–Alder reaction of the previously uncharacterized 3-(pyridin2-yl)phenathro[9,10-e][1,2,4]triazine (1) [14] with 1-morpholinocycloalkenes. A method for preparing different pyridine derivatives through reaction of the corresponding mononuclear 1,2,4-triazines has been known for some time [15-17]. In our work, we have used this method for the first time in a single-stage synthesis of the poorly available pyridyl-substituted monoazatriphenylenes 2a,b.

Aryne intermediates in the synthesis of polynuclear heterocyclic systems (Review)

Published examples of the polynuclear fused heterocyclic systems production by cycloaddition reactions involving aryne intermediates generated in situ are reviewed.

Chloromethyl-, dichloromethyl-, and trichloromethyl-1,2,4-triazines and their 4-oxides: method for the synthesis and tele-substitution reactions with C-nucleophiles

A simple procedure was developed for the synthesis of 1,2,4-triazines and their 4-oxides containing the ClCH2, Cl2CH, or CCl3 group at position 3 by cyclization of 2-aryl-2-hydrazono-1-oximinoethanes with the corresponding chloroacetonitriles. The reaction pathway depends on the number of halogen atoms in the acetonitrile used. The reactions with trichloroacetonitrile, monochloroacetonitrile, and dichloroacetonitrile afford 3-trichloromethyl-1,2,4-triazines, 3-chloromethyl-1,2,4-triazine 4-oxides, and a mixture of the corresponding dichloromethyltriazines and their 4-oxides, respectively. The reactions of 3-trichloromethyl-1,2,4-triazines with indoles and phenols are accompanied by tele-substitution with elimination of halogen from the trichloromethyl group to give 5-indolyl- (or 5-hydroxyphenyl)-3-dichloromethyl-1,2,4-triazines.

(Benzo[h])Quinolinyl-Substituted Monoazatriphenylenes: Synthesis and Photophysical Properties

We propose a method for the synthesis of quinolinyl- and benzo[h]quinolinylmonoazatriphenylenes through 1,2,4-triazine intermediates with subsequent transformations in aza-Diels–Alder reaction. The photophysical properties of these new compounds were examined, and the effects due to additional fused aromatic rings were explored.

8-Alkyl[1,2,4]Triazolo[5,1-b]Purines

A novel method has been developed for the synthesis of 8-alkyl[1, 2, 4]triazolo[5,1-b]purines from 6-nitro[1,2,4]triazolo[1,5-a]pyrimidin-7-ones via successive phosphoryl chloride-mediated chloro-desoxygenation, aminodehalogenation, and reduction to give 7-alkylamino-6-amino[1,2,4]triazolo-[1,5-a]pyrimidines. The latter can be cyclized in the presence of formic acid.

Spin-spin coupling constants 13C-15N and 1H-15N in the investigation of azido-tetrazole tautomerism in a series of 2-azidopyrimidines

A new method was developed for the investigation of an azido-tetrazole equilibrium based on using a complex analysis of 13C-15N and 1H-15N spin-spin coupling constants. The use of this approach became possible due to the selective inclusion of 15N isotopes into the structures of 2-azidopyrimidines and their cyclic analogs tetrazolo[1,5-a]pyrimidines.

Nitroazines. 5. Use of the japp-klingemann reaction for the synthesis of nitrotriazines

Condensation of diazoles with β-dicarbonyl nitro compounds (nitromalondialdehyde and nitromalondiester) gives derivatives of azolo[5,1-c] [1,2,4]triazine with a nitro group in the triazine ring.

The Extension of Conjugated System in Pyridyl-Substituted Monoazatriphenylenes for the Tuning of Photophysical Properties

We propose a method for the synthesis of diaryl-substituted pyridylmonoazatriphenylenes by the heterocyclization reaction of dihalosubstituted phenanthrenequinones with pyridine-2-carboxylic acid amidrazone, followed by aza-Diels–Alder reaction and Suzuki cross coupling. The obtained compounds showed more promising photophysical properties, compared to non-arylated analogs.

2-Azido-5-nitropyrimidine: Synthesis, Molecular Structure, and Reactions with N-, O-, and S-Nucleophiles

We describe the synthesis of 2-azido-5-nitropyrimidine and its azido-tetrazole tautomerism in various solvents and in the crystalline state. It was established that on interacting with N-nucleophiles the attack occurred at the C-2 carbon atom. The O- and S-nucleophiles attacked C-4 position of pyrimidine ring, resulting in tetrazole ring closure.