Monofluorinated Piperidines in Drug Discovery
Piperidine is one of the most widely used saturated nitrogen heterocycles in medicinal chemistry, appearing across approved drugs and discovery programmes. Within this familiar scaffold, introducing a single fluorine atom provides another way to tune molecular properties, particularly at positions such as C3 and C4. Fluorination can reduce the basicity of the piperidine nitrogen while also influencing conformation, lipophilicity and pharmacokinetic behaviour. This can be valuable when excessive basicity, hERG liability or poor clearance becomes a limitation in lead optimisation. A striking example comes from the optimisation of indirect AMPK activators. Introducing a trans-3-fluoro substituent onto a piperidine lead increased the hERG IC₅₀ from 4.7 to 69 µM, consistent with reduced piperidine basicity. The modification also reduced rat plasma clearance from 150 to 19 mL/min/kg, while the fluorinated analogue showed 55% oral bioavailability in rats. The motif has also been explored in other areas of drug discovery. A 3-axial-fluoropiperidine was identified during the optimisation of T-type calcium-channel antagonists, where reducing piperidine basicity contributed to an improved selectivity profile. Fluorinated piperidines have also featured in MET inhibitor programmes, demonstrating their use within oncology-focused medicinal chemistry. Beyond conventional drug discovery, 3-fluoropiperidines have been investigated as building blocks for ¹⁸F-labelled PET radiotracers targeting NR2B-containing NMDA receptors. Although the reported tracers showed limitations in brain uptake, the work demonstrates the broader value of fluorinated piperidines in molecular imaging and radiochemistry. Taken together, these examples show how replacing a single C–H bond with C–F can provide a useful additional dimension for tuning piperidine-containing molecules without abandoning a highly established medicinal-chemistry scaffold. Explore our range of building blocks using the advanced search tools at https://lnkd.in/eVbfw6Ua To read more: 1\) Synthesis and Chemoinformatic Analysis of Fluorinated Piperidines as 3D Fragments for Fragment-Based Drug Discovery \(J. Org. Chem. 2024\) https://lnkd.in/djzF3Fvi 2\) Synthesis of Enantiopure Fluoropiperidines via Biocatalytic Desymmetrization and Flow Photochemical Decarboxylative Fluorination https://lnkd.in/d\_Y5gnGF
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