Nickel Catalyzed Carbonylative Cross Coupling for Direct Access to Isotopically Labeled Alkyl Aryl Ketones.

Abstract

Here we present an effective nickel-catalyzed carbonylative cross-coupling for direct access to alkyl aryl ketones from readily accessible redox-activated tetrachlorophthalimide esters and aryl boronic acids. The methodology, which is run employing only 2.5 equivalents of CO and simple Ni(II) salts as the metal source, exhibits a broad substrate scope under mild condition. Furthermore, this carbonylation chemistry provides an easy switch between isotopologues for stable (13CO) and radioactive (14CO) isotope labeling, allowing its adaptation to the late-stage isotope labeling of pharmaceutically relevant compounds. Based on DFT calculations as well as experimental evidence, a catalytic cycle is proposed involving a carbon-centered radical formed via nickel(I)-induced outer-sphere decarboxylative fragmentation of the redox-active ester.