Co-Catalyzed Dehydrogenation Claisen Condensation of Secondary Alcohols with Esters†

Abstract

Catalytic dehydrogenation, with its exceptional atom economy and chemoselectivity, offers a highly desirable yet challenging approach for converting multiple environmentally friendly alcohols into crucial molecules. Furthermore, the utilization of catalysts based on abundant elements found on Earth for alcohol dehydrogenation to produce acryl ketone holds significant promise as a versatile strategy in synthesizing key building blocks for numerous pharmaceutical applications. The present study describes a practical Co-catalyzed cascade dehydrogenative Claisen condensation of secondary alcohols with esters, facilitating the synthesis of a wide range of 3-hydroxy-prop-2-en-1-ones. We introduce a catalytic system based on novel and scalable indazole NNP-ligands coordinated to cobalt for efficient dehydrogenations of secondary alcohols, and propose a plausible reaction mechanism supported by control experiments and labeling studies. Notably, it allows for the streamlined synthesis of multiple pharmaceuticals in one-pot.