Regioselective C-H Functionalization of the Six-Membered Ring of the 6,5-Fused Heterocyclic Systems: An Overview

The regioselective C-H functionalization of the five-membered ring of the 6,5-fused heterocyclic systems is nowadays well documented due to its high reactivity compared to the six-membered ring. So, developing new procedures of C-H functionalization of the six-membered ring “by thinking out of the box” is extremely challenging, which explains the limited number of reports published to date. This review paper aims to highlight advances achieved in this emerging chemistry research and discusses recently reported methods

Regioselective C-H Functionalization of the Six-Membered Ring of the 6,5-Fused Heterocyclic Systems: An Overview

The regioselective C-H functionalization of the five-membered ring of the 6,5-fused heterocyclic systems is nowadays well documented due to its high reactivity compared to the six-membered ring. So, developing new procedures of C-H functionalization of the six-membered ring “by thinking out of the box” is extremely challenging, which explains the limited number of reports published to date. This review paper aims to highlight advances achieved in this emerging chemistry research and discusses recently reported methods.</jats:p

Palladium-Catalyzed C3-Arylations of 1<i>H</i>- and 2<i>H</i>‑Pyrazolo[4,3‑<i>b</i>]pyridines on Water

Direct C3-arylation of 1H-pyrazolo­[4,3-b]­pyridines and direct C3-arylation of 2H-pyrazolo­[4,3-b]­pyridines in water has been developed. A new protocol for a sequential C3-arylation procedure on a mixture of 1H- and 2H-pyrazolo­[4,3-b]­pyridines followed by in situ PMB cleavage has also been achieved. This procedure led to unprotected (NH) C3-arylated 1H-pyrazolo­[4,3-b]­pyridines in good yields

Palladium‐Catalyzed Regioselective C−H Arylation of 4‐Azaindazole at C3, C5 and C7 Positions

International audienceDirect and site-selective C5 and C7 palladiumcatalyzed C-H arylations of 4-azaindazole N-oxide have been achieved. A bidentate ligand and Pd(OAc)2 catalyst in toluene promoted the activation of C5 position, while a phosphine ligand and PdCl2 catalyst in DMA directed the arylation at C7 position. Using this new method, the synthesis of C5, C7-diarylated 4-azaindazole N-oxides as well as the C3, C5 C7 triarylated 4-azaindazoles was achieved towards future medicinal compound development