Thieme Chemistry Journals Awardees - Where Are They Now? New Reaction Mode in Carboxylate-Directed C-H Functionalizations: Carboxylates as Deciduous Directing Groups

The widely available carboxylate groups have recently emerged as advantageous leaving groups for regioselective ipso substitutions and directing groups for ortho-C-H functionalizations in transition-metal catalysis. In the latter reactions, they can subsequently be transformed into a wealth of functionalities through decarboxylative ipso substitutions, or tracelessly removed through protodecarboxylation. The latest development in this field are reactions in which carboxylic acids function as deciduous directing groups, unlocking their unique potential for achieving regioselective monofunctionalization of a single ortho-C-H position. A deciduous directing group stays in place just long enough to direct an incoming reagent into a specific position and is then shed tracelessly as soon as the new C-C or C-heteroatom bond has formed. This inherently prevents unwanted double functionalization. This account discusses characteristics and synthetic opportunities of reactions with carboxylates as deciduous directing groups.