Copper(II)‐Catalyzed Selective Para Amination of Arylamine with Pyrazole by C−H Functionalization

Abstract

A coordinating activation strategy for selective para amination of arylamine with pyrazole is developed. Various substrates are compatible, giving the corresponding products in moderate to good yields. This strategy provides a practical solution for the efficient synthesis of arylamine‐containing pharmacophores from simple starting materials. A single electron transfer mechanism is suggested for this reaction.

Merging Photoredox Catalysis with Transition Metal Catalysis: Direct C4–H Sulfamidation of 1-Naphthylamine Derivatives

“…On the basis of above-mentioned observations and previous reports, − a possible mechanism for this transformation is illustrated in Scheme . Initially, the photocatalyst Eosin Y is excited by visible light to generate excited photocatalyst Eosin Y*, which undergoes a single-electron-transfer (SET) process with NHSI 2a to generate nitrogen-centered radicals A and Eosin Y •– .…”

“…Since Daugulis’ group developed the picolinamide (PA) moiety as a directing group to implement C–H functionalization in 2005, a number of reports for C2–H and C8–H functionalization reactions of 1-naphthylamine derivatives started to appear. Then, different types of C4–H functionalization of 1-naphthylamides derivatives have been introduced, such as sulfonylation, amination, , nitration, esterification, etherification . Especially in 2017, Lu described an efficient C4–H sulfamidation of 1-naphthylamine picolinamide with N -fluorobenzenesulfonimide (NFSI), but unfortunately, this work just gave one example and utilized 2 equiv of acetic acid.…”

A directing group switch in copper-catalyzed electrophilic C–H amination/migratory annulation cascade: divergent access to benzimidazolone/benzimidazole

“…Instead, thiophilic copper may endorse the extrusion of hydrogen sulfide to provide benzimidazole from the corresponding thioamide directing group (Scheme 1c). However, (1) copper-catalyzed C–H amination with a primary amine is a formidable challenge due to the catalyst inhibition; 18 (2) a deleterious intramolecular oxidative cyclization of the corresponding directing group may impede the cascade process 19 (Scheme 1d(i)); (3) competing peri - and para -C–H amination of naphthalene should be suppressed 20 (Scheme 1d(ii)). Furthermore, C–H amination with aliphatic primary amines is challenging and less explored.…”

Multicomponent Bifunctionalization of Methyl Ketones Enabled by Heterogeneous Catalysis and Solar Photocatalysis in Water

“…In order to meet the requirements of Green Chemistry, the development of an environment-friendly approach for organic synthesis has received considerable interest in recent years. − In general, organic transformations are performed in toxic and volatile organic solvents, which are not only non-renewable fossil fuels but also have potential toxicity and risks. Therefore, great effort has been devoted to developing aqueous phase reactions for organic synthesis. − In addition, as a renewable light energy, sunlight-induced photocatalytic reactions have become a green and simple strategy for organic transformation. − On the other hand, the development of multicomponent transformations has attracted extensive interest because they provide a greater impact with substantial minimization of waste, labor, time, and cost relative to linear syntheses. − Based on the urgent requirements of green synthesis and our research interests in developing green catalytic systems − and C–H functionalization reactions, − herein, we demonstrate a novel and green multicomponent transformation for the bifunctionalization of methyl ketones (Scheme b). In this transformation, ion-exchange resin Amberlyst 15 was used as the promising heterogeneous catalyst because of its recoverability and reusability. − In addition, quinoxalinones were selected as one of the reactants because they widely exist in natural products, functional materials, and pharmaceuticals. − In particular, 3-functionalized quinoxalinones are known for their superior chemical properties and outstanding biological activities, − …”