In this work, we show that the innate reactivity of the photoexcited state of a Mn-hydride complex can be harnessed to design the activation of the H2 molecule for catalytic applications. Such activation of molecular hydrogen by a photoexcited heavier 5d metal (Ir) complex has recently been achieved; however, it has been realized with an earth-abundant and lighter 3d metal complex. Here, we demonstrate that an in situ-generated Mn–H complex of an abnormal N-heterocyclic carbene can activate molecular hydrogen upon photoexcitation. The key to this approach lies in the fact that ground-state manganese hydride absorbs light to undergo homolytic cleavage, generating a metalloradical (Mn·) and a hydrogen atom. This, in turn, enables the formation of an O–H bond upon reaction with an aldehyde. Simultaneously, the generated Mn· can activate the H2 molecule, reproducing the Mn–H species in its ground state along with a hydrogen atom. The trapping of important intermediates, such as Mn· species and associated radical intermediates, using spectroscopic techniques confirms the mechanistic proposal involving the excited state of the Mn complex.

Photochemistry and total synthesis are deeply rooted in the history of organic chemistry, each developing independently while also intersecting frequently. Indeed, mild reaction conditions, versatility of transformations, and complementary selectivities to thermal methods make photochemistry an especially powerful tool for the synthesis of complex target molecules. In this Review, we highlight recent examples of total syntheses (from 2020 to 2025) featuring photochemical reactions as pivotal steps. Although the application of photochemistry in total synthesis has been consistently reviewed throughout the past decades, we feel that the wider emergence of photocatalytic methods, together with the continued importance of certain direct irradiation approaches, warrants its own discussion. We hope that our analytical approach and strategic insights will help us to identify cases where photochemical reactions could prove useful, thereby further encouraging their use in total syntheses.

Herein, we report a photocatalytic method for the selective functionalization of α-C(sp3)-H bonds adjacent to the nitrogen atom in amides. By harnessing a synergistic combination of hydrogen atom transfer (HAT), consecutive photoinduced electron transfer (ConPET), and reductive radical-polar crossover, we efficiently incorporated high-value electrophiles, including CO2, 13CO2, and deuterium, at the α-N position. The transformation proceeds in moderate to high yields across a diverse range of amides, representing a significant advancement in both isotopically labeled α-amino acid synthesis and amide deuteration.

Mineral acids promote nickel-catalyzed C(sp2)<span class='icomoon'></span>S cross-coupling of bromoanilines and related amine-containing electrophiles with thiols by protonating free amines, thereby facilitating oxidative addit...

Engineered NaYbF4:Tm3+@NaYF4 nanoparticles, featuring a fully sensitized Yb3+ lattice and an optimized core–shell architecture, convert five 980 nm photons by sequential absorption into a single 345 ...

Beilstein Journal of Organic Chemistry

A general strategy has been developed for predictable and robust vinyl halide cross-coupling reactions. This approach demonstrates broad applicability across seven distinct bond-forming transformatio...

Indanones are key structural motifs in pharmaceuticals and bioactive natural products, making their efficient synthesis a subject of continued interest. Conventional methods typically rely on transiti...

Enzyme engineering with photoswitchable unnatural amino acids (psUAAs) has a high potential for applications such as biocatalysis. Here, we extend the current repertoire of psUAAs to include more ver...

Azobenzene is a widely recognized tool for achieving artificial spatiotemporal control of enzyme activity through the use of light. Photocontrol reversibility is typically based on photostationary sta...

Magnetic stirrers, the most widely used and ubiquitous devices for performing chemical reactions in laboratory settings, may cause reproducibility problems. Reproducibility in a range of chemical proc...

Abstract: We report pyridine N-oxides as neutral ligands in cerium photocatalysis. By using those neutral ligands, photoactive Ce(IV)-species are generated, that show an extensive bathochromic shift ...

Photocatalytic reactions with a reductive radical-polar crossover (RRPCO) involve intermediates with carbanionic reactivity. These are best described as free carbanions. Reactions with such carbanion...

The development of photochemistry in water is rapidly advancing, and the demand for water-soluble photocatalysts is increasing. Accordingly, anthraquinone sulfonates are interesting options for the a...

Radical processes involving bismuth hold great potential, but innovative strategies are required to control the reactivity of bismuth intermediates. Herein, we report a direct photochemical decarboxy...

Visible light-driven proton transfer is crucial in nature and catalysis. Here, we report that protic merocyanine-based photoswitches act as efficient and recyclable homogeneous Brønsted acid catalysts...

The combination of photoinduced hydrogen atom transfer (HAT) and cobalt catalysis gives access to a mild dehydroformylation sequence for the defunctionalization of benzyl alcohols to arenes. The tran...

Lactam rings can be introduced to a diverse range of arenes and heteroarenes employing our mild and efficient photoredox method. The N-(het)arylation of lactams also works in aqueous media, allowing ...

Photoredox catalysis, which enables both electron and hydrogen atom transfer, has become a powerful tool for activating chemical bonds and synthesizing complex molecules under mild conditions. Typica...

Transition metal-catalyzed cross-coupling reactions are essential in modern organic synthesis, facilitating the rapid creation of complex molecular structures. Traditionally, these reactions rely heav...