C−H Activation Based Functionalization of Furfural Derivatives

Furfural and related compounds are building blocks of industrial interest, obtained from raw biomass. Their use as precursors of basic and fine chemicals has gained increasing attention as a green alternative to petroleum‐derived compounds. Several works have reported the functionalization of furfurals to obtain a wider range of chemicals, opening up new synthetic possibilities and applications, ranging from biofuels to pharmaceuticals. Among these works, processes based on C−H activation are the most attractive ones for their atom economy and the possibility to use non‐activated substrates. This minireview summarizes the reported methods of direct C−H functionalization of furfurals without prior modification of the redox state of the aldehyde function. In particular, the transition metal catalyzed functionalization of each bond of the heteroaromatic nucleus of these molecules is systematically discussed, as well as examples of C−H transformations of the aldehyde function. This Review summarizes the reported methods of direct C−H functionalization of furfurals without prior modification of the redox state of the aldehyde function. The aim is to illustrate the different approaches implemented for the functionalization of the C−H positions of the furan ring as well as of the aldehyde functional group.