Extended sulfonated bipyridine ligands targeting the para-selective borylation of arenes

Iridium-catalysed borylation of arenes is one the most widely used metal-catalysed C–H activation processes to elaborate aromatic rings. Exercising catalyst control over regioselectivity oxidative addition step remains an area active research. In this paper we describe synthesis a selection sulfonated bipyridine ligands in which there arene spacer between sulfonate group and backbone. comparison our previous work achieved meta-selective bore no spacer, hoped that these extended may allow larger macrocyclic transition state for thus favouring para-position. The synthesised have been evaluated on series bearing amides quaternary ammonium salts at varying distances from ring.