<i>ortho</i>‐Allylation of 2‐Arylindazoles with Vinyl Cyclic Carbonate and Diallyl Carbonate <i>via</i> Manganese‐Catalyzed C−H Bond Activation

Pyne

et al. 2022

The Chemical Record

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C−H Functionalization is ubiquitously considered as a powerful, efficient and handy tool for installing various functional groups in complex organic heterocycles in an easier and step‐economic way. Similarly, indazole is endowed as a potent heterocycle and is eminent for its profound impact in biological, medicinal and industrial chemistry. In this scenario, C−H functionalization at the selective ortho position of 2‐arylindazole in assistance of a metal catalyst is also becoming an appealing approach in synthetic organic chemistry. This review addressed the recent findings and developments on ortho C−H functionalization of 2‐aryl‐2H‐indazazoles with literature coverage extending from 2018 to May 2022.

Section: Allylationmentioning

confidence: 99%

OrthoC−H Functionalizations of 2‐Aryl‐2H‐Indazoles

Pyne

et al. 2022

The Chemical Record

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Recent Advances and Prospects in Manganese‐Catalyzed C−H Activation

Anusree,

Devi,

Anilkumar

2024

Adv Synth Catal

C–H activation represents an interesting alternative to conventional cross‐coupling methods, avoiding the requirement of additional steps to introduce activating groups. Generally, Pd‐catalyzed reactions have been extensively employed for C–H activation. The high cost and limited availability of resources of Pd have prompted us to explore alternative transition metals. In this context, researchers are turning to Earth Abundant Metals (EAMs) like manganese and iron for their potential in C–H activation.Significant progress has been made in manganese‐catalyzed C–H activation in recent years, showcasing excellent specificity, environmental compatibility, and versatility across different substrates. This review summarizes approximately 50 recent publications highlighting significant advancements in this field from 2020 to 2023.

Microwave‐Assisted Rhodium (III)‐Catalyzed [3+3] Annulation of 2‐Benzyl‐2H‐Indazole‐6‐carboxylic Acids with Iodonium Ylides: A Regioselective Synthesis of Indazole‐Fused Chromenes

Chen,

Barve,

Hsieh

et al. 2024

Adv Synth Catal

A Rh (III)‐catalyzed redox‐neutral C‐H activation/ [3+3] cyclization of 2‐benzyl‐2H‐indazole‐6‐carboxylic acids with iodonium ylides under microwave irradiation for the synthesis of indazole‐fused chromenes has been reported. The critical feature of this method is that the C‐H activation of the C7‐H bond of 2‐benzyl‐2H‐indazole‐6‐carboxylic acid proceeds with regioselectivity in the presence of the proximate C5‐H bond without the need for external oxidant. Microwave irradiation reduced the reaction time as compared to conventional heating. The detailed mechanistic study disclosed the mechanistic pathway of the reaction.