Ultrasound promoted mild and facile one-pot, three component synthesis of 2H-indazoles by consecutive condensation, C N and N N bond formations catalysed by copper-doped silica cuprous sulphate (CDSCS) as an efficient heterogeneous nano-catalyst
作者:Mohammad Navid Soltani Rad
DOI:10.1016/j.ultsonch.2016.07.026
日期:2017.1
An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an
Bu<sub>4</sub>NI-catalyzed, oxidative C<sub>(sp2)</sub>–C<sub>(sp3)</sub> cross dehydrogenative coupling for the regioselective direct C-3 benzylation of 2<i>H</i>-indazoles
作者:Lalit Yadav、Sandeep Chaudhary
DOI:10.1039/d0ob01282c
日期:——
A Bu4NI-catalyzed, DTBP-promoted, regioselective C(sp2)–C(sp3) cross dehydrogenative coupling (CDC) protocol for the direct C-3 benzylation of 2H-indazoles is reported. The metal-free protocol is operationally simple and proceeds mechanistically via the generation of stable benzylic free-radicals followed by regioselective addition at the C-3 position of 2H-indazoles which afforded C-3 benzylated 2H-indazoles
报道了一种 Bu 4 NI 催化、DTBP 促进的区域选择性 C (sp 2 ) -C (sp 3 )交叉脱氢偶联 (CDC) 方案,用于 2 H-吲唑的直接 C-3 苄基化。无金属方案操作简单,通过产生稳定的苄基自由基,然后在 2 H-吲唑的 C-3 位置进行区域选择性加成,得到 C-3 苄基化的2H-吲唑的产率高达 87%。该方法显示出一系列不同的官能团耐受性和广泛的底物兼容性。克级合成进一步突出了这种方法的重要性和通用性。
CuO nanoparticle catalysed synthesis of 2H-indazoles under ligand free conditions
作者:Nilufa Khatun、Anupal Gogoi、Pallabita Basu、Prasenjit Das、Bhisma K. Patel
DOI:10.1039/c3ra45298k
日期:——
A CuO nano catalysed one-pot synthesis of 2H-indazoles has been devised from easily accessible starting materials viz. 2-bromobenzaldehydes, primary amines and sodium azide under ligand free conditions. The nano CuO catalyst played an important role during the formation of the intermolecular C–N bond followed by the intramolecular N–N bond, providing 2H-indazoles. This method has a broad substrate scope with a high tolerance of a variety of functional groups. The catalyst can be recycled up to three times, however with slight decreases in the yields each time.
A general and efficient approach to 2H-indazoles and 1H-pyrazoles through copper-catalyzed intramolecular N–N bond formation under mild conditions
作者:Jiantao Hu、Yongfeng Cheng、Yiqing Yang、Yu Rao
DOI:10.1039/c1cc13908h
日期:——
A new efficient copper-catalyzed intramolecular amination reaction has been developed to readily synthesise a wide variety of multi-substituted 2H-indazole and 1H-pyrazole derivatives from easily accessible starting materials under mild conditions. A highly selective ligand for estrogen receptor β was prepared in three steps by employing this method.
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