Chemistry of heterocyclic N-oxides and related compounds

The dehydrogenating activity of 4-nitropyridine N-oxide and picolinic, nicotinic, isonicotinic, and quinolinic acid N-oxides was studied in the case of the reaction with the Hantzsch ester.See [1] for communication VIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1651–1653, December, 1977.     

Chemistry of heterocyclic N-oxides and related compounds

The corresponding deoxy bases were obtained by hydrogenation of pyridine and quinoline N-oxides by hydrogen transfer from cyclohexene, 1,4-dihydronaphthalene, tetralin, and formic acid on a palladium catalyst.See [1] for communication VI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 920–921, July, 1976.     

Chemistry of heterocyclic N-oxides and related compounds

The possibility of homogeneous dehydrogenation of anabasine with N-imines of pyridine, 2-picoline, and quinoline and of the Hantzsch ester with N-tosylimidopyridine and N-tosylimidoquinoline is shown.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–818, June, 1973.     

Chemistry of heterocyclic N-oxides and related compounds

Isonicoteine N-oxide and N-oxide were synthesized. A preparative method for the synthesis of anabasine Py-N-oxide is proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 378–380, March, 1973.The authors thank V. B. Leont'ev for his discussion of the UV, IR, and PMR spectra.     

Chemistry of heterocyclic N-oxides and related compounds

The synthesis of 2,3′-, 3,3′-, and 4,4′-dipyridyl N-tosylimides, for which the dehydrogenating activity was investigated in the case of reaction with the Hantzsch ester, was accomplished.     

Chemistry of heterocyclic N-oxides and related compounds VI. Reaction of pyridine,dipyridyl, and quinoline N-oxides with ammonia and ammonium salts

The amination of pyridine, quinoline, and 2,3- and 4,4-dipyridyl N-oxides with ammonia and ammonium salts in the presence of p-toluenesulfonyl chloride was studied. 2-Aminopyridine, N-(p-tosyl)-2-aminopyridine, and N-(p-tosyl)-2,2-dipyridyls were obtained in reactions with pyridine N-oxide. 2-Aminoquinoline was obtained in the amination of quinoline N-oxide. Dipyridyl N-oxides do not undergo amination.See [1] for communication V.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 229–232, February, 1976.     

Chemistry of heterocyclic N-oxides and related compounds. V. Dehydrogenation of the Hantzsch ester by means of pyridinioacylamidates

The dehydrogenating activity of pyridinioacetamidate, pyridiniobenzamidate, and pyridiniobenzenesulfonamidate was investigated in the case of reactions with the Hantzsch ester.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 226–228, February, 1976.     

Chemistry of heterocyclic N-oxides and related compounds. 11. Reaction of pyridine N-oxide with metal ketyls and benzophenone dianions

The reaction of pyridine N-oxide with metal ketyls of benzophenone was studied. It is shown that diphenyl(2-pyridyl)carbinol N-oxide is formed with the lithium and sodium derivatives of benzophenone, whereas diphenyl(2-pyridyl)carbinol is formed with the potassium derivative of benzophenone. Diphenyl(2-pyridyl)carbinol N-oxide is obtained in lower yields in the reaction of pyridine N-oxide with benzophenone dianions. Pyridine and 4,4- and 2,2-dipyridyls are simultaneously formed in all of the reactions.See [1] for Communication 10.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 655–658, May, 1979.     

Chemistry of heterocyclic N-oxides and related compounds 13. Acylamination of pyridine N-oxide by aniline,p-anisidine,and their N-p-tosyl derivatives

Acylamination of pyridine N-oxide by aniline, p-anisidine, and their tosyl derivatives was carried out in an alkaline medium in the presence of p-tosyl chloride. The reaction proceeds selectively with the formation of the corresponding 2-(N-p-tosyl) anilino- and 2-p-(N-p-tosyl)anisidino-pyridines. The reaction products were converted by acid hydrolysis into the corresponding 2-anilinopyridines.For communication 12, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–938, July, 1986.     

Chemistry of heterocyclic N-oxides and related compounds. 10. Reaction of pyridine N-oxide with 4-methyl- and 4-phenyl-substituted hantzsch esters

The corresponding dehydrogenation products were obtained in the reaction of diethyl 1,4-dihydro-2,4,6-collidine-3,5-dicarboxylates and diethyl 1,4-dihydro-4-phenyl-2, 6-lutidine-3,5-dicarboxylate with pyridine N-oxide. The reaction with dihydrocollidine is accompanied by simultaneous demethylation in the 4 position and methylation of the pyridine ring.See [1] for Communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 652–654, May, 1979.     

Deoxygenation of quinoxaline N-oxides and related compounds

The alkali induced deoxygenation of 3-(α-hydroxyalkyl)-quinoxaline-1-oxides is shown to be first order in substrate and in hydroxide ion. Examples are given to illustrate the synthetic utility of this reaction for the synthesis of quinoxaline and quinoline derivatives of type 4, 5, 8, and 11. The mechanism of the reaction is related to the mechanism of deoxygenation of heteroaromatic N-oxides by sodium dithionite.     

Energetic heterocyclic N-oxides: synthesis and performance

Novel synthetic strategies toward construction and functionalization of nitrogen-rich energetic compounds bearing at least one heterocyclic N-oxide scaffold are briefly overviewed. The present focus review summarizes main recent advances (published in the period 2017–2022) in the chemistry of five- and six-membered heterocyclic N-oxides as well as their linear combinations and fused bi-, tri- and tetraheterocyclic frameworks which are of paramount importance for the development of next-generation energetic materials. Physicochemical properties along with detonation performance and mechanical sensitivities of the reported high-energy substances are discussed and their application potential is especially emphasized.     

Synthetic and biological studies of pyrazolines and related heterocyclic compounds

This review provides a comprehensive survey relating to the synthesis and biological applications of pyrazolines and related heterocycles in the last five years (2007–2011). These compounds are usually prepared from the cyclization of chalcones with hydrazine and its derivatives under the alcoholic conditions. The major incentive behind the synthesis of these compounds was the immense biological activities associated to these heterocyclic derivatives. The aim of this review is to find out different methods for the synthesis of pyrazoline derivatives.     

Chemistry of heterocyclic compounds LV Platinum(O) complexes of heterocyclic acetylenes: Bis-Lithiation

Low temperature bis-metal—halogen exchange on a platinacyclic moietyis reported to occur without cleavage of the zero-valent platinumalkyne bond(s). The metallation procedure affords a convenient, mild route to metalate, dehalogenate, label, and/or functionalize metallacycles.     

Chemistry of thienopyridines. XLII. Three novel compounds derived from thienopyridine N-oxides

Extension of the Reissert-Henze reaction to treatment of thieno[2,3-b]pyridine 7-oxide with potassium thiocyanate and benzoyl chloride in water-methylene chloride gives a 2% yield of bis(6-thieno[2,3-b]pyridyl) disulfide. Peroxidation of 5-ethylthieno[2,3-b]pyridine ( 4 ) forms the 7-oxide 5 (53%), converted to a monopicrate 5a . Picrate 5a undergoes N-deoxygenation to 4 -picrate on drying at 78° in vacuo, but shows the expected additive mass spectrum of 5 (thermally stable) and picric acid. Nucleophilic displacement of chloride ion from 7-chlorothieno[3,2-b]pyridine (derived, in turn, from thieno[3,2-b]pyridine 4 -oxide) by the anion from ethyl cyanoacetate gives 7-(1-cyano-1-ethoxycarbonyl)methylene-4,7-dihydrothieno[3,2-b]pyridine (82%), stable in this iminodienic tautomeric form.     

A practical and mild chlorination of fused heterocyclic N-oxides

Fused azine N-oxides were selectively chlorinated at C2 in moderate to excellent yields, employing Vilsmeier reagent as both the activating agent and the nucleophilic chloride source. Remarkable features of the method include simple operation, mild reaction conditions, a wide substrate scope, and the use of only stoichiometric amount of POCl_3. The potential extension of this method to a one-pot oxidation/chlorination sequence that obviates the need for isolation of the N-oxide intermediates is also validated.