Bioisosteric Design in Medicinal Chemistry

Bioisosteric design has become a cornerstone of modern drug discovery, enabling the systematic replacement of functional groups or ring systems to fine-tune pharmacological profiles. By exchanging classical aromatic motifs for three-dimensional, C(sp3)-rich scaffolds, medicinal chemists can improve solubility, metabolic stability and target selectivity while reducing off-target toxicity. Advances in synthetic methodology have unlocked access to a diverse array of heterobicyclic and saturated isosteres, overcoming long-standing challenges of strain and regioselectivity. The strategic use of these novel cores not only expands the accessible chemical space but also introduces new exit vectors for ligand–receptor engagement. Together, these developments underscore the global significance of bioisosteric approaches in delivering safer, more efficacious therapeutics.

Research from Nature Portfolio

Recent studies have demonstrated highly modular photoredox-catalysed methods to install heterobicyclic motifs as isosteres of key heterocycles, offering a direct route to C(sp3)-rich scaffolds that mimic the geometry of pyridine and pyrimidine while improving solubility and metabolic stability. In parallel, asymmetric polar cycloadditions under chiral Lewis acid catalysis have enabled the stereocontrolled construction of bicyclo frameworks bearing congested quaternary centres with enantiomeric purity approaching 99%, greatly expanding the chiral toolkit for drug discovery. Additionally, the strategic exploitation of bicyclobutane strain-release has been harnessed in versatile addition and rearrangement reactions, unlocking rapid assembly of complex three-dimensional architectures and providing novel vectors for ligand–target interactions.

Bioisosteric Design in Medicinal Chemistry publication trend

The graph below shows the total number of articles in bioisosteric design in medicinal chemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Bioisosterism: The substitution of an atom or functional group with another that retains biological activity while modulating physicochemical properties.

Bicycloalkane: A saturated hydrocarbon featuring two bridgehead atoms connected by multiple ring pathways, often used as three-dimensional isosteres of aromatic rings.

Strain-release reactivity: Chemical transformations driven by relief of ring strain, enabling efficient bond formation under mild conditions.

Exit vector: The spatial orientation of substituents on a molecular scaffold that influences the direction and strength of binding interactions with a biological target.

References

1. Photoredox-catalysed amidyl radical insertion to bicyclo[1.1.0]butanes. Nature Catalysis (2024).
2. Enantioselective formal (3 + 3) cycloaddition of bicyclobutanes with nitrones enabled by asymmetric Lewis acid catalysis. Nature Communications (2024).
3. Bicyclobutanes as unusual building blocks for complexity generation in organic synthesis. Communications Chemistry (2023).
4. Two‐ and Three‐dimensional Rings in Drugs. Chemical Biology & Drug Design (2014).
5. Cyclobutanes in Small‐Molecule Drug Candidates. ChemMedChem (2022).
6. Rings in Clinical Trials and Drugs: Present and Future. Journal of Medicinal Chemistry (2022).