A Biphilic Phosphetane Catalyzes N–N Bond-Forming Cadogan Heterocyclization via P<sup>III</sup>/P<sup>V</sup>═O Redox Cycling
作者:Trevor V. Nykaza、Tyler S. Harrison、Avipsa Ghosh、Rachel A. Putnik、Alexander T. Radosevich
DOI:10.1021/jacs.7b03260
日期:2017.5.24
chemoselective catalytic synthesis of 2H-indazoles, 2H-benzotriazoles, and related fused heterocyclic systems with good functional group compatibility. On the basis of both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic PIII/PV═O cycling, where DFT modeling suggests a turnover-limiting (3+1) cheletropic addition between the phosphetane catalyst and nitroarene
A simple and direct approach for the regioselective construction of the privileged 2H‐indazole scaffold is described. The developed one‐pot strategy involves phospholene‐mediated N−N bond formation to access 2H‐indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2‐nitrobenzaldehydes and primary
Regioselective C3–H Trifluoromethylation of 2<i>H</i>-Indazole under Transition-Metal-Free Photoredox Catalysis
作者:Arumugavel Murugan、Venkata Nagarjuna Babu、Ashok Polu、Nagaraj Sabarinathan、Manickam Bakthadoss、Duddu S. Sharada
DOI:10.1021/acs.joc.9b00676
日期:2019.6.21
Trifluoromethyl-substituted heteroarenes are biologically active compounds and useful building blocks. In this sequence, we have developed a visible-light-promoted regioselective C3–H trifluoromethylation of 2H-indazole under metal-free conditions, which proceeds via a radical mechanism. The combination of photocatalysis and hypervalent iodine reagent provides a practical approach to a library of trifluoromethylated
A rhodium-catalyzed alcohol-mediated ortho-functionalization of 2-aryl-2H-indazoles through sequential C-H activation and carbenoid insertion with diazotized Meldrum's acid was developed. Using the 2H-indazole as the directing group and alcohol as the alkyl source, a series of ortho-alkylated aryl-2H-indazoles were obtained over a wide structural scope with high site-selectivity and excellent functional-group
heteroarenes are biologically active compounds and useful building blocks. In this study, we have developed a metal- and oxidant-free, environmentally friendly protocol for the regioselective selenylation of 2H-indazole derivatives by an electrochemical strategy. A number of selenylated 2H-indazoles with a wide range of functional groups have been synthesized in moderate to good yields under mild and