Photocatalytic Strategies in Organic Synthesis

Photocatalysis has emerged as a transformative platform for driving chemical bond formations under mild conditions using visible light. By harnessing the energy of photons, photoredox catalysts promote single-electron transfer processes that generate reactive radical intermediates, enabling a range of C–C, C–H and heteroatom bond-forming reactions. Complementary energy‐transfer pathways permit activation of otherwise inert substrates through triplet sensitisation. Recent advances have seen the integration of photocatalysis with transition-metal or organocatalytic cycles in dual-catalytic systems, affording complex molecular scaffolds in a single operation. Furthermore, electron donor–acceptor (EDA) complexes allow catalyst-free light absorption, expanding the scope of visible-light-driven transformations. Collectively, these strategies deliver high chemo- and regioselectivity, enhanced step and atom economy, and sustainable profiles by obviating stoichiometric oxidants and enabling hydrogen evolution in acceptorless processes. Applications span late-stage functionalisation of bioactive molecules, feedstock conversion and polymer modification, underscoring global significance in medicinal chemistry, materials science and green synthesis.

Research from Nature Portfolio

A synergistic photoredox–cobaloxime dual catalytic system has been developed to effect an oxidative [4+2] annulation of styrenes with alkynes under external-oxidant-free conditions, liberating hydrogen gas and constructing aromatic cores in a single step at ambient temperature. This approach exemplifies atom- and step-economy ideals by merging radical generation with proton reduction, transforming simple feedstocks into high-value targets with exceptional functional group tolerance and minimal waste.

Photocatalytic Strategies in Organic Synthesis publication trend

The graph below shows the total number of articles in photocatalytic strategies in organic synthesis across all publications each year (not limited to Nature Index journals).

Technical terms

Photoredox catalysis: Activation of substrates via single-electron transfer under light irradiation, generating radical species.

Electron donor–acceptor (EDA) complex: A noncovalent assembly that absorbs visible light to induce intracomplex electron transfer.

Dual catalysis: Concurrent use of two distinct catalysts (for example photoredox and transition-metal) to enable orthogonal activation modes.

C–H functionalisation: Direct transformation of a C–H bond into C–X or C–C bonds without prefunctionalisation.

Energy transfer: Sensitisation pathway in which excited catalyst transfers energy to a substrate, promoting bond activation without redox events.

References

1. Oxidative [4+2] annulation of styrenes with alkynes under external-oxidant-free conditions. Nature Communications (2018).
2. Photoinduced oxidative activation of electron-rich arenes: alkenylation with H 2 evolution under external oxidant-free conditions. Chemical Science (2018).
3. Visible-light-induced cross-coupling of aryl iodides with hydrazones via an EDA-complex. Chemical Science (2022).
4. Visible-Light Photoredox Catalyzed Dehydrogenative Synthesis of Allylic Carboxylates from Styrenes. Organic Letters (2021).