2-Aminophenyl-1H-pyrazole as a Removable Directing Group for Copper-Mediated C–H Amidation and Sulfonamidation

Abstract

2-Aminophenyl-1H-pyrazole was discovered as a removable bidentate directing group for copper-mediated aerobic oxidative C(sp(2)-H) bond amidation and sulfonamidation. When Cu(OAc)2 was employed as the copper source and 1,1,3,3-tetramethylguanidine as an organic base, the reaction, optimally carried out overnight in DMSO at 80 °C in open air, produced a variety of amides and sulfonamides in moderate to excellent yields. This directing group has proven to be particularly efficient in C-H sulfonamidation.

Copper‐Mediated Tandem C(sp2)‐H Amination and Annulation of Arenes with 2‐Aminopyridines: Synthesis of Pyrido‐fused Quinazolinone Derivatives

“…First, coordination of N,N ‐bidentate substrate 2 a with Cu(OAc) 2 followed by ligand exchange generates intermediate A , which undergoes intramolecular C−H cupration to afford the aryl/Cu II species B . Cu(OAc) 2 ‐promoted oxidation of B may lead to the formation of copper(III) complex C , . C will next react with 2‐aminopyridine to produce copper complex D ,.…”

C–H Functionalization of Aromatic Amides

“…In 2016, ortho ‐C–H sulfonamidation of aromatic amides was achieved by Li and co‐workers used 2‐aminophenyl‐1 H ‐pyrazole as the bidentate directing group and Cu(II) as the catalyst (Scheme ) . The optimum conditions for the reaction were Cu(OAc) 2 as a catalyst, 1,1,3,3‐tetramethylguanidine (TMG) as a base, DMSO as a solvent, and overnight at 80 °C.…”

Recent Progress on Copper-Mediated Directing-Group-Assisted C(sp2)–H Activation

“…Very recently, Li and co-workers employed 2-aminophenyl-1H-pyrazole as a new directing group for coppermediated C-H amidation and sulfonamidation reactions, which could expand the repertoire of removable DGs for copper catalysis. 61 Introducing the CF 3 group into organic molecules is highly important due to its widespread application in medicinal chemistry. In recent years, direct C-H trifluoromethylation of arenes has emerged as an attractive approach to generate C-CF 3 bonds.…”