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 visible-light-promoted regioselective C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalyticamount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature underaerobicconditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields
A Facile One-Step Synthesis of 2-Arylindazoles via Reductive Cyclization of<i>N</i>-(2-nitroarylidene)amines
作者:Wei Lin、Minghua Hu、Xian Feng、Chengpao Cao、Zhibin Huang、Daqing Shi
DOI:10.1002/jhet.2221
日期:2015.7
A mild and efficient synthesis of 2‐arylindazole derivatives via the reductivecyclization of nitro‐aryl substrates mediated by a low‐valent titanium reagent (TiCl4/Sm/Et3N) has been developed. The attractive features of the current method include an N–N bond formation and the selective reduction of the C = N bond and nitro group, both of which were easily achieved in one‐pot by controlling the pH
通过低价钛试剂(TiCl 4 / Sm / Et 3 N)介导的硝基芳基底物的还原环化,可以温和有效地合成2-芳基吲唑衍生物。当前方法的吸引人的特征包括N–N键的形成以及C = N键和硝基的选择性还原,通过控制反应混合物的pH值,很容易在一个锅中完成这两个操作。
Rhodium(<scp>iii</scp>)-catalyzed <i>ortho</i>-C–H amidation of 2-arylindazoles with a dioxazolone as an amidating reagent
has been established for the first time through a rhodium-catalyzed C-H activation reaction with alkyl, aryl and heteroaryl dioxazolones. A series of N-(2-(2H-indazol-2-yl)phenyl)acetamide derivatives were synthesized in excellent yields. A mechanistic study was conducted to describe C-H bondcleavage which is likely to be involved in the rate determining step.
We report a regioselective remote difunctionalization of unreactive C–H bonds of 2H-indazoles with Koser's reagents to provide C-4,7 substituted 2H-indazole derivatives.