method for constructing 1,4-pyrazoles from arylglycines was developed using the copper-catalyzed sydnone–alkyne cycloaddition reaction. The procedure offers a straightforward and general route to the pyrazole heterocycle through a three-step one-pot procedure.
Pyrazole Synthesis Using a Titanium-Catalyzed Multicomponent Coupling Reaction and Synthesis of Withasomnine
作者:Supriyo Majumder、Kevin R. Gipson、Richard J. Staples、Aaron L. Odom
DOI:10.1002/adsc.200900293
日期:2009.8
coupling of an alkyne, isonitrile, and amine can be used to generate tautomers of 1,3-diimines. These diimines produced in situ undergo cyclization with hydrazine and hydrazine derivatives in a one-pot procedure to provide pyrazoles. Seventeen examples of pyrazoles are provided using this one-pot, 4-component procedure from simple starting materials. The regioselectivity of the alkyne addition can be
1,3-Difunctionalization of β-Alkyl Nitroalkenes via Combination of Lewis Base Catalysis and Radical Oxidation
作者:Ye Wang、Lei Zheng、Xiaodong Shi、Yunfeng Chen
DOI:10.1021/acs.orglett.0c04106
日期:2021.2.5
catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylicnitrocompounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent
An immunoassay‐based method was used to screen numerous combinations of dipoles and dipolarophiles for their ability to undergo chemoselective and biocompatible [3+2] cycloaddition reactions. The approach fulfills most of the requirements of the click concept and led to the discovery of a copper‐catalyzed reaction that generates pyrazoles from sydnone and alkyne reagents.
Cu-catalysed pyrazole synthesis in continuous flow
作者:Júlia Comas-Barceló、Daniel Blanco-Ania、Sebastiaan A. M. W. van den Broek、Pieter J. Nieuwland、Joseph P. A. Harrity、Floris P. J. T. Rutjes
DOI:10.1039/c5cy02247a
日期:——
The synthesis of 1,4-disubstitutedpyrazoles via the cycloaddition reaction of sydnones and terminal alkynes has been achieved employing silica-supported copper catalysts. Furthermore, this methodology has been successfully implemented in continuous flow conditions using prepacked stainless steel cartridges containing the solid-supported copper promoter. Finally, we demonstrate that this synthetic