Copper-Promoted Oxidative Intramolecular C-H Amination of Hydrazones to Synthesize 1<i>H</i>
-Indazoles and 1<i>H</i>
-Pyrazoles Using a Cleavable Directing Group
A facile and efficient copper‐promoted oxidative intramolecular C–H amination of hydrazones for the synthesis of 1H‐indazoles and 1H‐pyrazoles was developed using a tracelessly cleavable directing group. This reaction is characterized by its mild conditions, operational simplicity, readily available reagents, and excellent yields. A tentative mechanism for Cu‐mediated C–H‐oxidative amination was proposed
A novel strategy for the crossdehydrogenativecoupling (CDC) of acetophenone hydrazones and aldehydes has been developed for the synthesis of highly substituted pyrazoles. This work, for the first time, uses elemental sulfur as a promoter as well as a hydrogen acceptor in effecting the Csp(3)-Csp(2) bond formation via C-H activation.
Synthesis and Theoretical Study of a Series of 3,5-disubstitutes Pyrazoles
作者:Karine Braga Enes、Ana Clara Alves Branco、Maria Eduarda Toledo Lima、Marcella Fernandes Mano Mateus、Luciana Guimaráes、Clebio Soares Nascimento、Mara Rubia Costa Couri
DOI:10.2174/1570178617666200409095632
日期:2020.12.8
In this work, we proposed the synthesis of a series of pyrazoles derivatives with different substituents on the aromatic rings. We aim to evaluate their influence on the reactivity of the compounds in reactions of α,β-unsaturated chalcones and sulfonyl hydrazide catalyzed by iodine. In order to explain their high and low yields, or the impossibility of obtaining some compounds by applied synthetic
Fast and Efficient Continuous Flow Method for the Synthesis of Ynones and Pyrazoles
作者:Mohanraj Kandasamy、Balaji Ganesan、Min-Yuan Hung、Wei-Yu Lin
DOI:10.1002/ejoc.201900468
日期:2019.6.2
An efficientmethod for the synthesis of ynones and polysubstituted pyrazoles in a continuous flow system through the generation of activated lithium acetylide. This system serves as a powerful strategy for a rapid, easy, and transition metal free process performed under mild reaction conditions, which provides a better reagent controll compared to the available benchtop methods.
Iron(III) phthalocyanine chloride-catalyzed oxidation–aromatization of α,β-unsaturated ketones with hydrazine hydrate: Synthesis of 3,5-disubstituted 1H-pyrazoles
We have developed an iron(III) phthalocyanine chloride-catalyzed oxidation–aromatization of α,β-unsaturated ketones with hydrazine hydrate. Various 3,5-disubstituted 1H-pyrazoles were obtained in good to excellent yields. This method offers several advantages, including room-temperature conditions, short reaction time, high yields, simple work-up procedure, and use of air as an oxidant. The catalyst