Tandem Oxidative Reaction of 1,3-Diarylpropenes and 5-Aminopyrazoles

Abstract

Mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the reaction of aminopyrazoles and 1,3-diarylpropenes is disclosed, which further undergoes intramolecular cyclization and dehydro-aromatization in the presence of Cu(OTf)2/tert-butyl hydroperoxide (TBHP). A series of pyrazolo[3,4-b]pyridines are obtained in moderate to excellent yields. It has the advantages of high atom economy, wide substrate scope, and one-pot procedure.

Recent advances in TBHP‐promoted heterocyclic ring construction via annulation/cyclization

“…An important class of heterocycles included in many licenced medications and therapeutic prospects are pyrazolo[3,4‐ b ]pyridines [52]. After intramolecular cyclization and dehydroaromatization in the presence of Cu(OTf) 2 /TBHP, the reaction of 5‐aminopyrazoles ( 49 ) with 1,3‐diarylpropenes ( 50 ), mediated by 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone, produced a series of pyrazolo[3,4‐ b ]pyridines ( 51 ) in moderate to excellent yields [53]. The reaction offers the benefits of a one‐pot process, a broad substrate range, and great atom economy.…”