C–H Functionalization Strategies for Heteroaromatic Compounds

C–H functionalization of heteroaromatic compounds has emerged as a transformative platform for the direct modification of pyridines, indoles, quinolines and related scaffolds. By converting unactivated C–H bonds into C–C, C–N or C–O linkages, these strategies bypass the need for prefunctionalised substrates and streamline synthetic routes to complex molecules. Contemporary approaches exploit radical pathways, transition-metal catalysis and organocatalysis to achieve high levels of chemo-, regio- and stereocontrol. Photoredox and hydrogen-atom-transfer processes generate carbon-centred radicals that engage electron-deficient heteroarenes via addition and rearomatization, while directing groups and non-covalent interactions have been employed to steer selectivity. The advent of predictive computational tools and machine-learning models now complements experimental design, enabling late-stage diversification of bioactive leads and rapid access to pharmaceutically relevant architectures on both small and large scale.

Research from Nature Portfolio

Recent studies have demonstrated the power of machine-learning to forecast the site-selectivity of radical additions to heteroaromatic cores. A message-passing neural network trained with ^13C NMR data accurately predicts atom-wise probabilities for Minisci‐type and P450-mediated functionalizations, outperforming traditional reactivity indices when validated against prospective experiments. This advance promises to de-risk late-stage functionalization campaigns by guiding reagent selection and protecting labile motifs.

Another innovative report employs N-F activation under visible light to drive oxidative cross-coupling between alcohols and protonated heteroarenes without external photocatalysts. The protocol exemplifies redox-neutral C–H arylation of primary and secondary α-positions in alcohols, delivering heteroaryl ethers under mild conditions and illustrating the potential for dual activation strategies in direct heteroarene functionalization.

C–H Functionalization Strategies for Heteroaromatic Compounds publication trend

The graph below shows the total number of articles in c–h functionalization strategies for heteroaromatic compounds across all publications each year (not limited to Nature Index journals).

Technical terms

C–H functionalization: Transformation of a carbon–hydrogen bond into a new bond, often C–C or C–heteroatom, without pre-activation.

Minisci reaction: Radical addition of nucleophilic carbon radicals to protonated heteroarenes followed by rearomatization to forge C–C bonds.

Photoredox catalysis: Use of visible light and a photocatalyst to generate reactive radicals through single-electron transfer.

Enantioselectivity: Preferential formation of one enantiomer over another in a chiral product.

Regioselectivity: Preference for functionalisation at one position over others within a molecule.

Late-stage functionalization (LSF): Introduction of new functionality into advanced intermediates or complex molecules to enable rapid diversification.

References

1. Discovery and Development of the Enantioselective Minisci Reaction. Accounts of Chemical Research (2023).
2. Predictive Minisci late stage functionalization with transfer learning. Nature Communications (2024).
3. Photocatalytic Enantioselective Radical Cascade Multicomponent Minisci Reaction of β‐Carbolines Using Diazo Compounds as Radical Precursors. Advanced Science (2024).
4. Photoredox-mediated Minisci C–H alkylation of N -heteroarenes using boronic acids and hypervalent iodine. Chemical Science (2016).
5. Visible light-induced direct α C–H functionalization of alcohols. Nature Communications (2019).