Metathesis-active ligands enable a catalytic functional group metathesis between aroyl chlorides and aryl iodides

Current methods for functional group interconversion have, for the most part, relied on relatively strong driving forces which often require highly reactive reagents to generate irreversibly a desired product in high yield and selectivity. These approaches generally prevent the use of the same catalytic strategy to perform the reverse reaction. Here we describe a catalytic functional group metathesis approach to interconvert, under CO-free conditions, two synthetically important classes of electrophiles that are often employed in the preparation of pharmaceuticals and agrochemicals—aroyl chlorides (ArCOCl) and aryl iodides (ArI). Our reaction design relies on the implementation of a key reversible ligand C–P bond cleavage event, which enables a non-innocent, metathesis-active phosphine ligand to mediate a rapid aryl group transfer between the two different electrophiles. Beyond enabling a practical and safer approach to the interconversion of ArCOCl and ArI, this type of ligand non-innocence provides a blueprint for the development of a broad range of functional group metathesis reactions employing synthetically relevant aryl electrophiles. Functional group interconversion typically requires reactive reagents to irreversibly generate a desired product in high yield and selectivity. Now, a CO-free catalytic functional-group-metathesis approach can be used to interconvert aroyl chlorides and aryl iodides—two important classes of electrophiles often employed in the preparation of pharmaceuticals and agrochemicals—with the help of metathesis-active phosphine ligands.