Remote Steric Control for Site-Selective Synthesis

Abstract

Control of site selectivity for organic synthesis in general, and for transition-metal-catalyzed C-H functionalization in particular is an important and challenging task. Steric interactions have been widely used to control reaction selectivity, but these strategies are largely limited to proximity sites. Recently, control of site selectivity through remote steric interactions has emerged as an attractive strategy that can enable selective reactions at distal sites from a steric marker. This review will cover recent developments in this area, with a focus on borylation reactions and transition-metal-catalyzed C-H activation.

Noncovalent interaction with a spirobipyridine ligand enables efficient iridium-catalyzed C–H activation

“…This is in contrast to strategies based on other noncovalent interactions such as hydrogen bonding, Lewis acid–base, and ion-pair interactions, which require a specific substituent or heteroatom on the arene, resulting in an inherent limitation in scope. We expect that spirobipyridine derivatives will find broad applications as a ligand in transition metal catalysis 67 , and we are further investigating the use of attractive interactions to accelerate catalytic C–H activation. We also believe that ligand KIE studies, largely ignored to date 42 , are a useful tool for investigating noncovalent interactions between the catalyst and substrate, and we are working towards better understanding of these effects.…”