Revisiting aromatic diazotization and aryl diazonium salts in continuous flow: highlighted research during 2001–2021

Aryl diazonium salts play an important role in chemical transformations; however their explosive nature limits their applications in batch.

Biaryl synthesis with arenediazonium salts: cross-coupling, CH-arylation and annulation reactions

The rich legacy of arenediazonium salts in the synthesis of unsymmetrical biaryls, built around the seminal works of Pschorr, Gomberg and Bachmann more than a century ago, continues to make important contributions at various evolutionary stages of modern biaryl synthesis. Based on in-depth mechanistic analysis and design of novel pathways and reaction conditions, the scope of biaryl synthesis with arenediazonium salts has enormously expanded in recent years through applications of transition metal/photoredox-catalysed cross-coupling, thermal/photosensitized radical chain CH-arylation of (hetero)arenes and arylative radical annulation reactions with alkynes. These recent developments have provided facile synthetic access to a wide variety of unsymmetrical biaryls of pharmaceutical, agrochemical and optoelectronic importance with green scale-up options and created opportunities for late-stage modification of peptides, nucleosides, carbon nanotubes and electrodes, the details of which are captured in this review.

Palladium-catalyzed dearomatizative [2 + 2 + 1] carboannulation of 1,7-enynes with aryl diazonium salts and H2O: facile synthesis of spirocyclohexadienone-fused cyclopenta[c]quinolin-4(5H)-ones

The first 1,7-enyne dearomatizative [2 + 2 + 1] carboannulation using aryl diazonium salts as the one-carbon units is described.

meso-Tetrakis[4-(methoxycarbonyl)phenyl]porphyrinatopalladium(ii) supported on graphene oxide nanosheets (Pd(ii)-TMCPP-GO): synthesis and catalytic activity

In this study, meso-tetrakis[4-(methoxycarbonyl)phenyl]porphynatopalladium(ii) as a macrocyclic palladium complex was covalently grafted to the surface of graphene oxide (Pd-TMCPP-GO). The prepared catalyst was checked in Suzuki reaction.

Cu(0) onto sulfonic acid functionalized silica/carbon composites as bifunctional heterogeneous catalysts for the synthesis of polysubstituted pyridines and nitriles under benign reaction media

Bifunctional heterogeneous catalysts based on Cu(0) onto sulphonated silica/carbon composites for the one-pot synthesis of polysubstituted pyridines and oxidative transformation of aldehydes to nitriles.