Heck Reactions of Acrolein or Enones and Aryl Bromides – Synthesis of 3‐Aryl Propenals or Propenones and Consecutive Application in Multicomponent Pyrazole Syntheses
作者:Marvin Stephan、Jesco Panther、Fabio Wilbert、Pauline Ozog、Thomas J. J. Müller
DOI:10.1002/ejoc.202000066
日期:2020.4.16
The Heck reaction of (hetero)aryl bromides and acrolein or vinyl ketones using CataCXium® Ptb as a ligand, NaHCO3 as a base, and nBu4NCl provides an efficient access to 3‐(hetero)aryl propenals/propenones, which are directly employed in consecutive multicomponent syntheses of pyrazoles in a one‐pot fashion.
使用CataCXium®Ptb作为配体,NaHCO 3作为碱和n Bu 4 NCl进行(杂)芳基溴化物和丙烯醛或乙烯基酮的Heck反应,可以有效地获得3-(杂)芳基丙烯/丙烯酮。以单罐方式直接用于吡唑的连续多组分合成中。
An Efficient Synthesis of Substituted Pyrazoles from One-Pot Reaction of Ketones, Aldehydes, and Hydrazine Monohydrochloride
hydrazine monohydrochloride readily formed pyrazoline intermediates under mild conditions. Oxidation of pyrazolines, in situ, employing bromine afforded a wide variety of pyrazoles. The methodology offers a fast, and often chromatography-free protocol for the synthesis of 3,4,5-substituted pyrazoles in good to excellent yields. Alternatively, a more benign oxidation protocol affords 3,5-disubstituted or
An iodine-catalyzed denitrative imino-diaza-Nazarov cyclization (DIDAN) methodology has been developed for the synthesis of pyrazoles with high to excellent yields by using α-nitroacetophenone derivatives and in situ generated hydrazones. The key transformation of this oxidative 4π-electrocyclization proceeds through an enamine–iminium ion intermediate. This rapid one-pot DIDAN protocol results in
The diaza-Nazarov cyclization involving a 2,3-diaza-pentadienyl cation for the synthesis of polysubstituted pyrazoles
作者:Balakrishna Aegurla、Rama Krishna Peddinti
DOI:10.1039/c7ob01949a
日期:——
diaza-Nazarov (DAN) type cyclization for the construction of substituted pyrazoles from easily available starting materials via an enamine–iminium ion intermediate is described. The oxidative cyclization worked under green conditions with remarkable regioselectivity. This one-pot, efficient and operationally simple three-component intramolecular regioselective DAN cyclization displayed a wide range of
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