A robust protocol for Pd(ii)-catalyzed C-3 arylation of (1H) indazoles and pyrazoles: total synthesis of nigellidine hydrobromide
作者:Mengchun Ye、Andrew J. F. Edmunds、James A. Morris、David Sale、Yejia Zhang、Jin-Quan Yu
DOI:10.1039/c3sc50184a
日期:——
indazole and pyrazoles are privileged structural motifs in agrochemicals and pharmaceuticals. C-3 C-H arylation of (1H) indazole and pyrazole has been a significant challenge due to the poor reactivity of the C-3 position. Herein, we report a practical Pd(II)/Phen catalyst and conditions for direct C-3 arylation of indazole and pyrazole with ArI or ArBr without using Ag additives as halide scavengers. The
Palladium-catalyzed C–N bond formation: synthesis of 1-aryl-1H-pyrazoles from β-bromovinyl aldehydes and arylhydrazines
作者:Chan Sik Cho、Daksha B. Patel
DOI:10.1016/j.tet.2006.04.031
日期:2006.6
Cyclic and acyclic β-bromovinyl aldehydes are cyclized with an array of arylhydrazines in toluene at 125 °C in the presence of a palladium catalyst and a phosphorus chelating ligand together with NaOtBu to give 1-aryl-1H-pyrazoles in moderate to good yields.
在钯催化剂和磷螯合配体以及NaO t Bu的存在下,在125°C下,用一系列芳基肼在甲苯中将环状和无环β-溴乙烯基醛环化,得到中度至中等浓度的1-芳基-1 H-吡唑良品率高。
Oxone-mediated facile access to substituted pyrazoles
An Oxone-mediated transition-metal-free oxidative C-N bond formation has been achieved for the regio-selective synthesis of substituted pyrazoles. The reactions accompany the chelation-controlled ortho-oxidation of N-substituted aromatic ring to provide phenol derivatives in some cases. This method displays a facile access to diverse range of substituted pyrazoles from readily accessible hydrazones. (C) 2015 Elsevier Ltd. All rights reserved.
Binuclear Pd(I)–Pd(I) Catalysis Assisted by Iodide Ligands for Selective Hydroformylation of Alkenes and Alkynes
is driven by a novel activation strategy and features a unique Pd(I)-Pd(I) mechanism, involving an iodide-assisted binuclear step to release the product. This method enables β-selective hydroformylation of a large range of alkenes and alkynes, including sensitive starting materials. Its utility is demonstrated in the synthesis of antiobesity drug Rimonabant and anti-HIV agent PNU-32945. In a broader