Osmium-Promoted Electrophilic Substitution of Anisoles: A Versatile New Method for the Incorporation of Carbon Substituents.

A structurally and electronically diverse set of anisoles are dihapto-coordinated to the pi-base pentaammineosmium(II) and treated with a variety of carbon electrophiles (e.g. Michael acceptors, acetals). After deprotonation of a 4H-anisolium intermediate with a tertiary amine base, C(4)-substituted anisole complexes are isolated. The functionalized arenes are removed from the metal center either by mild heating or treatment with an oxidant (e.g. AgOTf, DDQ, CAN). The resulting substituted anisoles are isolated with yields ranging from 55-95%.