نتایج جستجو برای: Pyridines

تعداد نتایج: 6741  

Journal: :Organic & biomolecular chemistry 2014
Wen-Bing Qin Jia-Yi Zhu Yu-Bo Kong Yun-Hong Bao Zheng-Wang Chen Liang-Xian Liu

Direct metal-free C-4-selective indolation of pyridines is achieved for the first time using TEMPO and (Boc)2O. A variety of substituents on both indoles and pyridines are tolerated to give 3-(pyridin-4-yl)-1H-indole derivatives in moderate to excellent yields. This finding provides a novel approach for developing metal-free C-H functionalization of pyridines.

Journal: :Organic & biomolecular chemistry 2013
Jonathan Macdonald Victoria Oldfield Vassilios Bavetsias Julian Blagg

We show that N3-MEM-protected imidazo[4,5-b]pyridines undergo efficient C2-functionalisation via direct C-H arylation. Twenty-two substituted imidazo[4,5-b]pyridines are prepared and iterative, selective elaboration of functionalised imidazo[4,5-b]pyridines gives 2,7- and 2,6-disubstituted derivatives in good yields from common intermediates. Mechanistic observations are consistent with a conce...

Journal: :Journal of the American Chemical Society 2008
James R Manning Huw M L Davies

A concise one-pot synthesis of highly functionalized pyridines has been developed. The first step in the reaction sequence is the formal insertion of rhodium vinylcarbenoids across the N-O bond of isoxazoles. Upon heating, the insertion products undergo a rearrangement to give 1,4-dihydropyridines. DDQ oxidation then affords the corresponding pyridines in 31-84% yield. The process has proven ge...

2013
Hermann Josef Frohn Thorsten Schroer Gerald Henkel

The arylxenonium cation in the salt [C6F5X e]+ [AsF6]" is isoelectronic to C6F5I, but coordinatively unsaturated with respect to N-bases like MeCN and pyridines. Co-ordination of strongly basic pyridines causes weakening of the Xe-C bond and C6F5 radical formation. The thermal decomposition of pyridine co-ordinated arylxenonium cations gives three groups of products: C-pentafluorophenylated pyr...

Journal: :Organic & biomolecular chemistry 2016
Chitrakar Ravi Darapaneni Chandra Mohan Subbarayappa Adimurthy

Copper-catalyzed regioselective C-3 sulfenylation of imidazo[1,2-a]pyridines using p-tosylchloride as a benign source of sulfenylating agents has been developed. On the other hand, p-tosylchloride mediated thiomethylation of imidazo[1,2-a]pyridines with dimethylsulfoxide as a source of thiomethylation under metal-free conditions was also described.

Journal: :Organic & biomolecular chemistry 2012
Hung-Chou Wu Chia-Wen Yang Long-Chih Hwang Ming-Jung Wu

Pyrazolo[1,5-a]pyridines and 6-iodopyrazolo[1,5-a]pyridines were synthesized by gold-catalyzed and iodine-mediated cyclization of enynylpyrazoles in good to excellent yields, respectively. The iodinated adducts were further converted to 6-arylpyrazolo[1,5-a]pyridines via Suzuki-Miyaura coupling reaction and 6-cyanopyrazolo[1,5-a]pyridine by Ullmann condensation reaction. One of the cyclization ...

2014
Yuanxiang Wang Brendan Frett Hong-yu Li

An expeditious one-pot, ligand-free, Pd(OAc)2-catalyzed, three-component reaction for the synthesis of 2,3-diarylimidazo[1,2-a]pyridines was developed under microwave irradiation. With the high availability of commercial reagents and great efficiency in expanding molecule diversity, this methodology is superior to the existing procedures for the synthesis of 2,3-diarylimidazo[1,2-a]pyridines an...

Journal: :Molbank 2021

The ammonium salts of many drugs have significantly improved the solubility and, accordingly, bioavailability medicinal substances in human body. 5-(4-Hydroxy-2-oxo-2H-chromen-3-yl)-5H-chromeno[2,3-b]pyridines are potential NPY1R ligands, which attractive for antiobesity treatment. Ammonium 5H-chromeno[2,3-b]pyridines were previously unknown. In this communication, it was found that four-compon...

2013
Daniel G Stark Louis C Morrill Pei-Pei Yeh Alexandra M Z Slawin Timothy J C O'Riordan Andrew D Smith

Acids to bases: The synthesis of 2,4,6-trisubstituted pyridines from (phenylthio)acetic acid and a range of α,β-unsaturated ketimines is reported. This process proceeds by intermolecular Michael addition/lactamization, thiophenol elimination, and N- to O-sulfonyl migration, giving 2-sulfonate-substituted pyridines which are readily derivatized to generate structural diversity.

2017
Nadia A. Abdelriheem Yasser H. Zaki Abdou O. Abdelhamid

BACKGROUND Pyrazolo[1,5-a]pyrimidines are purine analogues. They have beneficial properties as antimetabolites in purine biochemical reactions. This division compounds have attracted wide pharmaceutical interest because of their antitrypanosomal activity. RESULTS The present work depicts an effective synthesis convention of pyrazolo[1,5-a]pyrimidines, pyrazolo[5,1-c]triazines, thieno[2,3-b]py...

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