Halogenation of pyridinium-N-(2′-pyridyl)aminide: An easy synthesis of halo-2-aminopyridines (original) (raw)
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Tetrahedron, 2010
Dedicated to Professor Manuel Bernabé on the occasion of his 74th birthday a b s t r a c t Suzuki-Miyaura cross-coupling processes on N-pyridinium bromoazinyl aminides allow access to 3,5disubstituted N-alkyl-2-aminopyridines. The synthetic pathway involves a regioselective bromination of pyridinium N-(pyridin-2-yl)aminide and a subsequent reaction with boronic acids to afford monosubstituted aminides in good yields. An additional bromination in the 5-position of the pyridine ring followed by a coupling reaction gives pyridinium N-(3,5-diarylpyridin-2-yl)aminides. Finally, a regioselective alkylation on the exo-nitrogen and reduction of the N-N bond yields highly substituted 2-aminopyridines.
Tetrahedron, 2008
An extensive study of SuzukieMiyaura cross-coupling processes on N-pyridinium bromoazinyl aminides has been performed. Mono-and disubstitution on 5-and 3,5-bromo derivatives produced the corresponding aryl derivatives. In the disubstituted compounds regioselective substitution at the 3-position occurred, vicinal to the aminide nitrogen, and this was more evident in pyrazine derivatives. The commonly used strategy involving N-alkylation and reduction of the NeN bond gave rise to a series of 2-alkylamino-3,5-disubstituted-pyrazines.
Convenient Access to New 4-Substituted Aminopyrido [2,3-d]pyrimidine derivatives
Tetrahedron Letters, 2015
We describe in this Letter, a novel series of pyrido[2,3-d]pyrimidines 6-11 derived from 3-cyano-2aminopyridines 4a-f via formamidine formation 5a-f followed by selective nucleophilic addition, with different primary amines, under solvent-free conditions. The structures of the newly synthesized compounds are confirmed by spectral analysis. This new approach includes some important aspects such as mild reaction conditions, high yields, and environmentally friendly process. The operational simplicity of this synthetic route will offer an attractive alternative to the conventional methods.
Syntheses, Complexation and Biological Activity of Aminopyridines: A Mini-Review
2021
Aminopyridines are among the classes of heterocyclic compounds that have been extensively studied in the last few decades owing to their interesting biological activities. They exist in three isomeric forms: 2-aminopyridine, 3-aminopyridine and 4-aminopyridine. The diversity in their pharmacological activities has attracted the attention of many researchers to explore the reasons for their wide potential. This study examines recent advances related to the efficient procedure for synthesizing different types of aminopyridine derivatives, its coordination site with metals and biological activities using systematic literature review and content analysis. Other important concepts of aminopyridines discussed are basicity, electric hindrance as related to percentage yield of isomeric forms and spectra updates on the characterization of aminopyridines. The findings from this study also reveal the array of solvents used for purification processes; ideas on isomers that have not been used in...
New approaches to the synthesis of pyridinium N-heteroarylaminides
Tetrahedron, 2008
Different substituted pyridinium N-heteroarylaminides have been prepared in one step from N-aminopyridinium iodide and the corresponding heteroaryl halide by two alternative routes. The use of Pd catalysis allowed the easy preparation of products from the less reactive haloheterocycles. The use of water as a solvent in conjunction with microwave heating dramatically diminishes the reaction time without having an adverse effect on reaction yields.
2012
A direct conversion of 2-aminopyridine into 2,3-disubstituted imidazo[1,2-a]pyridines was studied. A series of products was obtained in an efficient, simple and fast protocol. The scope and limitation of the transformation are also studied and was found that its effectiveness and the type of the substituent at 3-position, 3-(1-arylethane) and/or 3-(1-arylethene), is strongly dependent both on the catalyst and on the ketone aromatic substituent. The structures of the products were assigned by 1D and 2D NMR spectra and confirmed by X-ray analyses of selected samples.