Decarboxylation and cross-coupling reactions of coumarin-3-carboxylic acid: a comprehensive review

The present review article offers an overview of the application of coumarin-3-carboxylic acids as a promising synthon in the synthesizing a diverse array of interesting biologically relevant organic molecules. This is accomplished, primarily through cross-coupling reactions, followed by subsequent decarboxylation, resulting in new reactivity patterns. The ability of the carboxylic acid moiety to enhance the electrophilic character of the directly attached olefinic carbon within a coumarin moiety, along with its feasibility for decarboxylation, opens up straightforward synthetic routes for numerous coumarin-derived molecules, including fused and hybrid heterocycles with remarkable regioselectivity (3-addition, 4-addition, or both). These advancements are primarily based on cascade reactions. This review article aims to provide readers with an up-to-date overview, encompassing contributions predominantly made in this challenging domain of organic synthesis during the last decade.