Applications of photocatalytic Hydrogen Atom Transfer (HAT) methodologies for the Late-Stage Functionalization (LSF) of complex molecules have been discussed in this perspective.

Lignin represents the largest renewable resource of aromatic moieties on earth and harbors a huge potential as a sustainable feedstock for the synthesis of biobased aromatic fine chemicals. Due to the complex, heterogeneous, and robust chemical structure of the biopolymer, the valorization is associated with significant challenges. Unfortunately, technical lignins, which are a large side stream of the pulp and paper industries, are mainly thermally exploited. In this study, technical Kraft lignin was selectively electrochemically depolymerized to the aroma chemical vanillin. Using electricity, toxic and/or expensive oxidizers could be replaced. The electrodegradation of Kraft lignin was performed at 160 °C in a simple undivided high-temperature electrolysis cell and studied in respect to several reaction parameters. At optimized electrolytic conditions vanillin could be obtained in high selectivity with 67% efficiency compared to the common nitrobenzene oxidation. Additionally, the established high-temperature electrolysis indicated a reliable process and could be easily adapted to a variety of different Kraft lignins.

The merging of a homogeneous photocatalytic system with an electrochemical cell, having exchanged electrons as the only common point, has been recently demonstrated. This combination opens unexplored pathways in synthesis and allowed net‐oxidative photocatalytic processes to be realized in the absence of a chemical oxidant, including: 1) the C−H alkylation of heteroarenes and 2) the coupling of azoles with arenes in the presence of an electrogenerated photocatalyst.

A photoelectrochemical strategy for the cross-dehydrogenative coupling of unactivated aliphatic hydrogen donors (e.g. alkanes) with benzothiazoles is reported. We used tetrabutylammonium decatungstate as the photocatalyst to activate strong C(sp3)–H bonds...