Catalytic C–H Bond Functionalization in Organic Synthesis

Catalytic C–H bond functionalization has emerged as a transformative paradigm in modern organic synthesis, enabling the direct conversion of ubiquitous carbon–hydrogen bonds into carbon–carbon or carbon–heteroatom linkages without pre-functionalisation. This approach dramatically streamlines synthetic routes by reducing the number of steps, minimising waste and enhancing atom economy. Central challenges include achieving high levels of regioselectivity and chemoselectivity in molecules bearing multiple C–H bonds and functional groups. Progress has been driven by the design of tailored transition-metal catalysts, the strategic use of directing groups and the development of alternative activation modes such as electrocatalysis and enzyme-mediated C–H insertion. Recent advances encompass ortho, meta and para selectivity control, remote site-selective transformations and late-stage modifications of complex natural products, pharmaceuticals and materials precursors. Collectively, these innovations promise to broaden the toolbox for the rapid assembly and diversification of molecular scaffolds that underpin drug discovery, agrochemicals and functional materials.

Research from Nature Portfolio

Recent studies have demonstrated palladium-electrochemical C–H olefination of simple arenes in the absence of directing groups, employing mild potentials rather than stoichiometric oxidants and achieving outstanding positional selectivity through a machine-learning model trained on physical organic parameters. Late-stage olefinations of pharmaceutically relevant scaffolds have been effected without protection or auxiliary manipulations. In parallel, ruthenium(II) catalysts exploiting a unique arene ligand effect have delivered a general platform for meta-selective alkylations, affording meta-decorated arenes including ketones, acids, amines and phenols in a step-economical fashion. Foundational work on benzoic acid derivatives has established nitrile-based sulfonamide templates for meta-C–H olefination and acetoxylation using molecular oxygen as the oxidant, thereby broadening the scope of direct, remote functionalisation strategies.

Catalytic C–H Bond Functionalization in Organic Synthesis publication trend

The graph below shows the total number of articles in catalytic c–h bond functionalization in organic synthesis across all publications each year (not limited to Nature Index journals).

Technical terms

Catalytic C–H bond functionalisation: Activation and transformation of a carbon–hydrogen bond into a new carbon–X linkage using a catalyst to improve step and atom economy.

Directing group: A coordinating moiety installed on a substrate to guide a catalyst to a specific C–H bond for regioselective activation.

Electrocatalysis: Catalysis driven by an applied electrical potential, enabling redox transformations without chemical oxidants or reductants.

Late-stage functionalisation: The modification of a complex molecule at a late point in its synthesis to introduce new functionalities without de novo assembly.

Nitrene radical intermediate: A nitrogen-centred radical species generated in situ during metal-catalysed nitrene transfer, responsible for selective C–H amination and aziridination.

References

1. Transition-Metal-Catalyzed C–H Bond Activation for the Formation of C–C Bonds in Complex Molecules. Chemical Reviews (2023).
2. Electrocatalyzed direct arene alkenylations without directing groups for selective late-stage drug diversification. Nature Communications (2023).
3. P450-Catalyzed Intramolecular sp3 C–H Amination with Arylsulfonyl Azide Substrates. ACS Catalysis (2014).
4. Nitrene Radical Intermediates in Catalytic Synthesis. Chemistry - A European Journal (2017).
5. Pd(II)-catalysed meta-C–H functionalizations of benzoic acid derivatives. Nature Communications (2016).
6. Ruthenium(II)-catalysed remote C–H alkylations as a versatile platform to meta-decorated arenes. Nature Communications (2017).