474352-67-5Relevant academic research and scientific papers
Iron complex-catalyzed N-arylation of pyrazoles under aqueous medium
Lee, Hang Wai,Chan, Albert S.C.,Kwong, Fuk Yee
, p. 5868 - 5871 (2009)
Commercially available FeCl3·6H2O with conformationally rigid diamine ligand is a highly effective catalyst for N-arylation of pyrazoles using aryl and heteroaryl iodides. It is notable to show that this complex is tolerable under aqueous medium and particularly the whole reaction utilizes water as the sole solvent without any additional organic co-solvents and surfactants. Attempted study using other nitrogen nucleophiles is described. This newly developed system provides an alternative protocol to Cu- and Pd-catalyzed N-arylation reactions.
Direct Formation of 2-Substituted 2 H-Indazoles by a Pd-Catalyzed Reaction between 2-Halobenzyl Halides and Arylhydrazines
Aljaar, Nayyef,Al-Noaimi, Mousa,Conrad, Jürgen,Beifuss, Uwe
, p. 1408 - 1418 (2021/01/14)
A direct and operationally simple method for the regioselective synthesis of 2-aryl-substituted 2H-indazoles is reported. The Pd-catalyzed reaction between easily available 2-bromobenzyl bromides and arylhydrazines employing Cs2CO3 as the base and t-Bu3PHBF4 as the ligand in DMSO at 120 °C in a sealed tube delivers the 2-substituted-2H-indazoles in a single synthetic step with yields up to 79%. The new method is based on a regioselective intermolecular N-benzylation followed by intramolecular N-arylation and oxidation.
Preparation method 2 - substituted - 222H-indazole compound
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Paragraph 0033-0035; 0043, (2020/10/19)
The invention provides a preparation method of a 2-substituent-2H-indazole compound. With a cuprous catalyst, a coupling reaction is carried out to substituted 1H-indazole and aryliodonium salt in a low-molecular polar organic solvent to obtain a corresponding 2-substituent-2H-indazole compound, wherein the molar ratio of the 1H-indazole to the aryliodonium salt is 1:1.2. According to the method,the reaction route starts from the 1H-indazole compound which is easy to obtain; with the low-cost cuprous compound as a catalyst, the reaction condition is gentle and yield of produced target compound is high. The method also has good compatibility with various functional groups and can be widely applied to synthesize 2-substituent-2H-indazole compounds having different substituent groups. The method has important application value.
Synthesis of (2H)-Indazoles from Azobenzenes Using Paraformaldehyde as a One-Carbon Synthon
Chun, Rina,Kim, Saegun,Han, Sang Hoon,Han, Sangil,Lee, Suk Hun,Mishra, Neeraj Kumar,Jung, Young Hoon,Kim, Hyung Sik,Kim, In Su
, p. 1617 - 1626 (2019/02/19)
Rhodium(III)-catalyzed hydroxymethylation followed by intramolecular annulation of azobenzenes using paraformaldehyde as a valuable C1-feedstock is described. The method is readily extended to the coupling reaction between azobenzenes and trifluoroacetaldehyde. This transformation efficiently produces a range of C3-unsubstituted and C3-trifluoromethylated (2H)-indazoles, which are important targets in the development of novel bioactive compounds. Excellent chemoselectivity and functional group tolerance were observed. The synthetic transformation of C3-unsubstituted (2H)-indazoles highlights the utility of the developed method. (Figure presented.).
Direct Acyl Radical Addition to 2 H-Indazoles Using Ag-Catalyzed Decarboxylative Cross-Coupling of α-Keto Acids
Bogonda, Ganganna,Kim, Hun Young,Oh, Kyungsoo
, p. 2711 - 2715 (2018/05/22)
A direct acyl radical addition to 2H-indazoles has been achieved for the first time, where the less-aromatic quinonoid 2H-indazoles readily accepted radical species to the C-3 position. Motivated by the lack of direct acylation strategy for 2H-indazoles, the current method utilizes the radical acceptability of 2H-indazoles, discovering an ambient temperature reaction to provide facile access to a diverse array of 3-acyl-2H-indazoles with three points of structural diversification in 25%-83% yields.
Access to 2-substituted-2: H -indazoles via a copper-catalyzed regioselective cross-coupling reaction
Zhang, Rong,Liu, Zheng,Peng, Qiujun,Zhou, Yijun,Xu, Lanting,Pan, Xianhua
supporting information, p. 1816 - 1822 (2018/03/23)
A CuCl catalyzed C-N cross-coupling reaction using commercially available 1H-indazoles with diaryliodonium salts is described. The methodology features ample structural versatility, affording 2-substituted-2H-indazole in good yields and complete N(2)-regiocontrol. Furthermore, the utility of the reaction was demonstrated in the synthesis of a known estrogen receptor β agonist. Mechanistic studies using density functional theory calculations suggested that the complete regioselectivity can be attributed to the only weak base TfO- in our system which could not deprotonate indazoles, and the catalyst oxidation process would be the rate-determining step.
