Tosyl Hydrazine-Promoted Tandem Condensation and Cyclization of Acyl Azobenzenes Enabling Access to 2H-Indazoles under Metal-Free Aerobic Conditions
Tosyl hydrazine-promoted tandem condensation and cyclization of 2-acyl azobenzenes under metal-free aerobic conditions was demonstrated to give 2-aryl-2H-indazoles having alkyl- or aryl groups at the 3-position in quantitative yields through the release o
Son, Jeong-Yu,Kim, Hyunseok,Baek, Yonghyeon,Um, Kyusik,Ko, Gi Hoon,Han, Gi Uk,Han, Sang Hoon,Lee, Kooyeon,Lee, Phil Ho
p. 4354 - 4361
(2018/10/02)
Rh(III)-Catalyzed [4 + 1]-Annulation of Azoxy Compounds with Alkynes: A Regioselective Approach to 2H-Indazoles
A rhodium-catalyzed regioselective C-H activation/cyclization of azoxy compounds with alkynes has been disclosed to construct a variety of 2H-indazoles. A [4 + 1]-cycloaddition rather than a normal [4 + 2] mode is observed in the process of cyclative capture along with an oxygen-atom transfer and a C≡C triple bond cleavage. This protocol features a broad substrate scope, a good functional group tolerance, and an exclusive regioselectivity.
Long, Zhen,Yang, Yudong,You, Jingsong
supporting information
p. 2781 - 2784
(2017/06/07)
Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C-H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh- and Co-systems. (Chemical Presented).
Geng, Xiaoyu,Wang, Congyang
supporting information
p. 2434 - 2437
(2015/05/27)
Direct access to acylated azobenzenes via Pd-catalyzed C-H functionalization and further transformation into an indazole backbone
Azobenzenes were readily acylated at the 2-position through a Pd-catalyzed C-H functionalization from simple aromatic azo compounds and aldehydes in good yields. The obtained acylated azobenzenes could be efficiently converted into the corresponding indaz
Li, Hongji,Li, Pinhua,Wang, Lei
p. 620 - 623
(2013/04/10)
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