Benzyl Palladium Intermediates: Unique and Versatile Reactive Intermediates for Aromatic Functionalization

Abstract

AbstractAromatic functionalizations are of current interest and importance in organic chemistry, recent transition‐metal catalyzed reactions can transform inert C−H bond into C−X (X=C, O, N, etc.) bonds, greatly enriching aromatic chemistry and related fields. Some well‐known palladium‐containing intermediates such as palladacycles and allylpalladium intermediates play an important role in organic conversions. Similar with allyl group, benzyl group also possesses the capability of stabilizing palladium through η3‐binding. In the process of the formation of benzyl palladium intermediate, there is a transition state of dearomatization. Therefore, it is a challenging and meaningful research topic to seize these aromatic destruction intermediates, realize selective functionalization reaction on aromatic ring via them, and inhibit the formation of traditional benzylated products. Herein, we summarized the recent efforts on expanding the synthetic utility, as well as exploring the mechanism in aromatic functionalization via reactive benzyl palladium intermediates. We envision that the transformation via benzyl palladium intermediates will help promote the development in the field of palladium–catalyzed aromatic regioselective functionalization.magnified image