Synthesis of pyrido[1,2-b][2,4]benzodiazepin-6(11H)-imines

Condensation of o-bromomethylbenzonitrile and -bromo-o-cyanophenylmethane with 2-aminopyridines gives 6-amino-6,11-dihydropyrido[1,2-b][2,4]benzodiazepines. Quaternary 2-aminopyridinium salts are intermediates in these reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1264–1269, September, 1987.     

Synthesis of 3-substituted N-aminopyridinium salts

Ring opening of N-(2,4-dinitrophenyl)pyridinium chlorides with hydrazine followed by recyclization resulted in the formation of N-aminopyridinium salts. The scope of this reaction sequence was determined and several new 3-substituted N-aminopyridinium salts were prepared.     

Metal-free synthesis of pyridin-2-yl ureas from 2-aminopyridinium salts

An unprecedented base promoted domino approach has been developed for the synthesis of pyridin-2-yl urea derivatives via the reaction of 2-aminopyridinium salts and arylamines. The developed strategy tolerated a wide range of functional groups and afforded pyridin-2-yl ureas in moderate to good yields. The reaction was postulated to involve tandem cyclization, intermolecular nucleophilic addition, ring opening, and demethylation.     

Synthesis of pyridine and pyrimidine derivatives by reaction of pyrylium salts with ureas,thioureas, and isothioureas

2,4,6-Triphenylpyrylium perchlorate is converted to 2,4,6-triphenylpyridine in reactions with urea and N-acetyl- and N,N-dimethylureas, whereas it is converted to 1,2,4,6-tetraphenylpyridinium perchlorate on reaction with N,N-diphenylurea. The reaction of pyrylium perchlorates with thiosemicarbazide and semicarbazide leads to 1-thiocarbamido- and 1-carbamidopyridinium salts. The latter reacts with 2,4,6-triphenylpyrylium perchlorate to give 1-aminopyridinium salts, which were acylated with acetic anhydride. Difficult-to-obtain 2-alkylthio-4,6-diarylpyrimidines were synthesized in 40–93% yields by the reaction of 2,4,6-triarylpyrylium salts with S-alkylisothioureas.Translated from Khuniya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–328, March, 1979.     

Anion-Radical Salts of 7,7,8,8-Tetracyanoquinodimethane (TCNQ) with Cations Based on Amino-Chloropyridines

Anion-radical salts of 7,7,8,8-tetracyanoquinodimethane (TCNQ) with N-methyl-2-amino-5-chloropyridinium and N-methyl-2-chloro-3-aminopyridinium cations of simple and complex compositions were synthesized and studied. The salt (N?CH₃?2?Cl₃NH₂?Py)(TCNQ) is electrically conducting and thermally stable up to 340°C. This enables use of this anion-radical salt in electronics of organic materials.

     

2-Methylpyridinium salts as 1,4-dinucleophiles. IV. Westphal condensation with 2-alkyl-1-aminoazinium substrates

Condensation of 2-alkyl-1-aminopyridinium, quinolinium or 1-alkyl-2-aminoisoquinolinium salts with 1,2-acenaphthenequinone or 9,10-phenanthrenequinone in the presence of base, gave pyrido[1,2-b]pyridazinium salts in good yields.     

Synthesis and properties of aza analogs of merocyanine dyes based on N-substituted 2- and 4-aminopyridinium salts

Russian Chemical Bulletin - A series of aza analogs of the merocyanine dyes based on 1-N-alkyl-2- and 1-N-alkyl-4-aminopyridinium salts and ethoxymethylidenemalononitrile was synthesized. Their...     

The preparation,structure and reactions of some “malonyl-α-aminopyridines”

The reaction of several substituted 2-aminopyridines with diethyl malonate was studied. The “methylmalonyl-α-aminopyridines” were shown to exist in the same tautomeric form as “malonyl-α-aminopyridine”. Formylation of these compounds takes place in the 3-position and has led to the formation of a new tricyclic compound.     

Synthesis of substituted 4-pyridones and 4-aminopyridinium salts via a one-pot pyridine synthesis

Synthesis of substituted 4-benzyloxypyridinium salts by the addition of Grignard reagents to pyridine N-oxides provides an efficient route for obtaining substituted 4-pyridones or 4-aminopyridinium salts.     

Copper(I) π-complexes with 2-butyne-1,4-diol. Synthesis and crystal structure of (2-AmpH)[CuCl<Subscript>2</Subscript>(HOCH<Subscript>2</Subscript>C≡CCH<Subscript>2</Subscript>OH)] (2-AmpH<Superscript>+</Superscript> is 2-aminopyridinium cation)

Crystals of the π-complex (2-AmpH)[CuCl₂(HOCH₂C≡CCH₂OH)] (2-AmpH⁺ is the 2-aminopyridinium cation) were obtained by the reaction of 2-butyne-1,4-diol with CuCl in aqueous 2-aminopyridinium chloride solution and studied by X-ray diffraction: space group P \(\overline 1 \), a= 7.172(4), b= 7.796(3), c = 11.60(9) Å, α = 99.75(6)°, β = 96.53(7)°, γ = 101.03(3)°, Z = 2. The crystals consist of individual anions [CuCl₂(HOCH₂C≡CCH₂OH)]^? and cations [2-AmpH]⁺. The π-coordinated Cu(I) atoms of the complex anion have trigonal-planar surrounding of two chlorine atoms and C≡C bond of the 2-butyne-1,4-diol molecule. The alcohol groups form stable hydrogen bonds N-H?O (1.89 Å) and O-H?Cl (2.20 Å).     

Reaction of barbituric/thiobarbituric acid with phosphines or phosphites and dialkyl acetylenedicarboxylates for synthesis of phosphorus zwitterions or phosphonate derivatives

Abstract

A three-component reaction between barbituric/thiobarbituric acid, phosphines, and dialkyl acetylenedicarboxylates in dry acetonitrile led to the formation of barbiturate/thiobarbiturate-functionalized stable zwitterionic salts in a one-pot process. When trialkyl phosphites were used instead of phosphines, barbiturate/thiobarbiturate-functionalized phosphonates were obtained in good yields.     

Reactions of α-perfluorophenylpyrylium perchlorates with hydrazine hydrate

Reactions of α-perfluorophenylpyrylium salts with hydrazine hydrate in ethanol afforded derivatives of 1,2-diazepine, dihydro-1H-pyrazole, and/or 1-aminopyridinium salts, depending on the steric characteristics of the substituent in the second α-position. 1-Amino-2-methyl-6-perfluorophenyl-4-phenylpyridinium perchlorate was used to obtain various pyridocyanines.     

Electrophilic Tropylation of Aminopyridines and 4-Aminoquinoline

Russian Journal of General Chemistry - The reactions of 2-, 3-, 4-aminopyridines or 4-aminoquinoline with hydrolytically stable tropylium salts (perchlorate or tetrafluoroborate) have afforded...     

Synthesis of new heterocycles festooned with thiophene and evaluating their antioxidant activity

The chemical performance of 5-bromo-2-(bromoacetyl)-thiophene ( 1 ) was tested toward the reaction with numerous bi-nucleophilic reagents (namely; 2-aminobenzothiazoles, 2-aminothiazole, 2-aminotetrazole, 2-aminotriazole, 2-aminopyridines, 2-aminobenzimidazole and o-phenylenediamine). Therefore, a series of bridged nitrogen heterocycles bearing thiophene moiety 3 , 5 , 7 , 9 , 11 , 13 and 15 , respectively was synthesized. In addition, the reaction of 5-bromo-2-(bromoacetyl)-thiophene with the thiocarbamoyl compounds 17 , 19 and/or 24 afforded the corresponding thienyl-thiazoles 18 or dithien-2-yl ketones 20 and 25 , based on the reaction conditions. Treatment of 1 with 2-mercapto-4,6-dimethylnicotinonitrile was achieved to obtain the target dithien-2-yl ketone 28 . The new synthesized scaffolds were examined for their antioxidant activity by means of ABTS antioxidant assay. The thienyl-thiazole scaffold 18c and 2-((2-[thiophen-2-yl]-2-oxoethyl)thio)nicotinonitrile derivative 27 displayed a reasonable radical scavenging activity.     

Synthesis of imidazopyridines from the morita-baylis-hillman acetates of nitroalkenes and convenient access to alpidem and zolpidem

A variety of functionalized imidazo[1,2-a]pyridines have been synthesized through a one-pot, room temperature, and reagent-free reaction between MBH acetates of nitroalkenes and 2-aminopyridines. The reaction involves a cascade inter-intramolecular double aza-Michael addition of 2-aminopyridines to MBH acetates. Our methodology is marked by excellent yield, regioselectivity and, above all, adaptability to synthesize imidazopyridine-based drug molecules such as Alpidem and Zolpidem.     

Synthesis of pyridines by heterocyclization of new dienamino esters

The synthesis of pyridine derivatives is reported starting from the new dienamino esters 2 . Thermal cyclization of 2 afforded the ethyl 2-amino-3-pyridinecarboxylate derivatives 3 ; from the reaction of 2 in sodium ethoxide the 2-aminopyridines 3 and 4 , and the 1,2-dihydro-2-oxopyridines 5 and 6 were obtained.     

A new solvent system for recycling catalysts for chelation-assisted hydroacylation of olefins with primary alcohols

A new method to separate and reuse the catalyst system consisting of a rhodium complex and 2-aminopyridines for chelation-assisted hydroacylation was achieved using phenol and 4,4'-dipyridyl as the reaction medium, and 4-diphenylphosphinobenzoic acid as a ligand.     

Practical and scalable preparation of Minodronic acid and Zolpidem from 2-chloroimidazole[1,2-a]pyridines

Practical and scalable procedures for Minodronic acid and Zolpidem are developed with short reaction sequences from 2-aminopyridines and maleic anhydride, respectively. The new procedures avoid column chromatography for the purification in all synthetic steps. Key aspects of this development involve reductive hydrodechlorination and Suzuki coupling reaction of 2-chloroimidazole[1,2-a]pyridines, and their application towards synthesis of the two drugs is also addressed.     

A four-component, one-pot synthesis of highly substituted 1,4-dihydro-1,8-naphthyridine-3-carboxamides

A new, one-pot, four-component reaction for the synthesis of a novel class of highly substituted 1,4-dihydro-1,8-naphthyridine-3-carboxamide derivatives starting from readily available inputs including aliphatic or aromatic amines, diketene, aromatic aldehydes, and 2-aminopyridines in the presence of a catalytic amount of p-toluenesulfonic acid under mild reaction conditions and in good yields at ambient temperature is described.     

The Schmidt reaction with pyridine carboxylic acids

The Schmidt reaction in oleum is used to prepare 2, 3-and 4-aminopyridines.