A New Class of Pyrazolopyridine Nucleus with Fluorescent Properties, Obtained through Either a Radical or a Pd Arylation Pathway from N-Azinylpyridinium N-Aminides
摘要:
The synthesis of dipyridopyrazole and pyridopyrazolopyrazine derivatives--both of which incorporate a 3-aryl moiety--can be achieved in moderate yields by intramolecular radical arylation of pyridinium N-aminides using tris(trimethylsilyl)silane and azobisisobutyronitrile. Improved results were obtained on using Pd direct arylation in conjunction with microwave irradiation. A preliminary study into the fluorescent properties of the target compounds is also reported.
Pd-catalyzed reactions on pyridinium N-heteroarylaminides. Step-by-step synthesis of 3,5-unsymmetrically disubstituted 2-aminopyridines
摘要:
Suzuki-Miyaura cross-coupling processes on N-pyridinium bromoazinyl aminides allow access to 3,5-disubstituted N-alkyl-2-aminopyridines The synthetic pathway involves a regioselective brommation of pyridinum N-(pyridin-2-yl)aminide and a subsequent reaction with boronic acids to afford monosubstituted aminides in good yields An additional brommation 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 (C) 2010 Elsevier Ltd All rights reserved
Suzuki reaction on pyridinium N-(5-bromoheteroar-2-yl)aminides
作者:M. José Reyes、M. Luisa Izquierdo、Julio Alvarez-Builla
DOI:10.1016/j.tetlet.2004.09.136
日期:2004.11
The reactivity of substituted pyridinium N-(2'-azinyl)aminides in Suzuki-Miyaura cross-coupling reaction is reported. The reaction proceeds in good yield employing Cs2CO3 as base, and producing substitution on the negatively charged moiety. (C) 2004 Published by Elsevier Ltd.
Suzuki reaction on pyridinium N-haloheteroarylaminides: regioselective synthesis of 3,5-disubstituted 2-aminopyrazines
作者:Rafael Castillo、M. José Reyes、M. Luisa Izquierdo、Julio Alvarez-Builla
DOI:10.1016/j.tet.2007.11.057
日期:2008.2
An extensive study of Suzuki-Miyaura 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 N-N bond gave rise to a series of 2-alkylamino-3,5-disubstituted-pyrazines. (c) 2007 Elsevier Ltd. All rights reserved.