3-(4-Fluorobenzyl)piperidine: Properties, Uses & Research Guide

3-(4-Fluorobenzyl)piperidine is a fluorinated piperidine derivative widely employed as a versatile synthetic building block in medicinal chemistry and pharmaceutical research.

Chemical Name

3-(4-Fluorobenzyl)piperidine

Molecular Formula

C₁₂H₁₆FN

Molecular Weight

193.26 g/mol

Core Scaffold

Piperidine ring with a 4-fluorobenzyl substituent at the 3-position

Key Functional Groups

Secondary amine (piperidine N–H), aryl fluoride

Primary Research Use

Medicinal chemistry intermediate and CNS-targeted drug discovery

Aladdin SKU

P708684

Chemical Structure and Physicochemical Properties

3-(4-Fluorobenzyl)piperidine consists of a six-membered saturated piperidine ring bearing a 4-fluorobenzyl group at the 3-position. The molecular formula is C₁₂H₁₆FN with a molecular weight of approximately 193.26 g/mol. The compound contains two key pharmacophoric elements: a basic secondary amine within the piperidine ring, which can be readily functionalized or protonated under physiological conditions, and an aryl fluoride moiety that confers metabolic stability and modulates lipophilicity relative to the unsubstituted benzyl analog.

The presence of fluorine on the aromatic ring is a well-recognized strategy in drug design. Fluorine's high electronegativity and small atomic radius allow it to mimic hydrogen while significantly altering electronic distribution, binding affinity, and metabolic resistance. The 3-substitution pattern on the piperidine ring introduces a stereocenter, meaning the compound exists as a racemate unless enantioselectively synthesized, which is an important consideration for biological evaluation and regulatory purposes.

Synthesis and Role as a Medicinal Chemistry Building Block

Piperidine-containing scaffolds are among the most prevalent nitrogen heterocycles found in approved pharmaceuticals and drug candidates. 3-(4-Fluorobenzyl)piperidine serves as a valuable synthetic intermediate due to its secondary amine, which can be selectively acylated, sulfonylated, alkylated, or reductively aminated to produce a diverse array of target molecules. This flexibility makes it particularly useful in fragment-based drug discovery and lead optimization campaigns.

The 4-fluorobenzyl group is commonly incorporated into drug candidates to improve pharmacokinetic properties. Fluorination at the para position of a benzyl group typically raises metabolic stability by blocking cytochrome P450-mediated oxidation at that site, while the fluorine atom can also participate in orthogonal interactions such as C–F···H–N hydrogen bonding or dipole-dipole interactions within a binding pocket. Researchers should handle the secondary amine with care during multi-step synthesis to avoid undesired side reactions; protection as a Boc or Cbz carbamate is a standard approach prior to transformations at sensitive sites.

Research Applications in CNS and Drug Discovery

Fluorobenzylpiperidine motifs appear across multiple therapeutic areas, with particular prevalence in central nervous system (CNS) drug discovery. Piperidine-based compounds interact with a wide range of neurological targets including monoamine transporters, G protein-coupled receptors (GPCRs), and ion channels. The basic nitrogen of the piperidine ring facilitates salt formation and can engage in electrostatic interactions with aspartate or glutamate residues in receptor binding sites.

Researchers working on dopaminergic, serotonergic, or adrenergic receptor modulators frequently incorporate fluorobenzylpiperidine units as part of their pharmacophore. The compound may also serve as a precursor in the synthesis of protease inhibitors, kinase inhibitors, and other small-molecule therapeutics outside the CNS field. Its relatively low molecular weight (193.26 g/mol) and the presence of a single nitrogen atom make it an attractive fragment that complies with Lipinski's rule-of-five guidelines, leaving ample room to add functionality while maintaining drug-likeness.

Handling, Storage, and Laboratory Safety

As with most secondary amine-containing building blocks, 3-(4-Fluorobenzyl)piperidine should be stored in a tightly sealed container under cool, dry conditions, away from strong oxidizers and acids. The free base form of piperidine derivatives is typically moisture-sensitive and may absorb carbon dioxide from air to form a carbamic acid salt over time; therefore, storage under an inert atmosphere (nitrogen or argon) is recommended for long-term preservation of purity.

Researchers should consult the Safety Data Sheet (SDS) provided by Aladdin Scientific before use. Standard laboratory personal protective equipment (PPE) — including chemical-resistant gloves, safety goggles, and a lab coat — should be worn. Work in a well-ventilated fume hood is advised when weighing or dissolving the compound. Waste disposal should comply with local regulations for organic nitrogen-containing compounds.

Frequently asked questions

What is the CAS number for 3-(4-Fluorobenzyl)piperidine?

The CAS number for 3-(4-Fluorobenzyl)piperidine should be confirmed directly from the Aladdin Scientific product page or the certificate of analysis for SKU P708684, as specific registry numbers require verified sourcing to ensure accuracy.

Is 3-(4-Fluorobenzyl)piperidine available as a single enantiomer?

The 3-position substitution creates a chiral center, so the compound exists as a racemic mixture unless specified otherwise. Researchers requiring enantiopure material should contact Aladdin Scientific to inquire about chiral variants or plan an enantioselective synthesis from their own starting materials.

What solvents are suitable for dissolving 3-(4-Fluorobenzyl)piperidine?

Piperidine derivatives are generally soluble in polar organic solvents such as dichloromethane, methanol, ethanol, and dimethyl sulfoxide (DMSO). Solubility in aqueous buffers can be achieved by forming the hydrochloride salt or by adjusting the pH. Researchers should perform a solubility check at their target concentration prior to biological assays.

How can the secondary amine of 3-(4-Fluorobenzyl)piperidine be selectively functionalized?

The secondary amine can be functionalized via acylation with acyl chlorides or anhydrides, sulfonylation with sulfonyl chlorides, reductive amination with aldehydes, or direct alkylation. For reactions at other positions, the amine should first be protected using standard protecting groups such as Boc (di-tert-butyl dicarbonate) or Cbz (benzyl chloroformate).

References

1. Lipinski CA, Lombardo F, Dominy BW, Feeney PJ. Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings. Advanced Drug Delivery Reviews. 2001;46(1-3):3-26. doi:10.1016/s0169-409x(00)00129-0
2. Müller K, Faeh C, Diederich F. Fluorine in pharmaceuticals: looking beyond intuition. Science. 2007;317(5846):1881-1886. doi:10.1126/science.1141704
3. Roughley SD, Jordan AM. The medicinal chemist's toolbox: an analysis of reactions used in the pursuit of drug candidates. Journal of Medicinal Chemistry. 2011;54(10):3451-3479. doi:10.1021/jm200187y
4. Aladdin Scientific. Product page: 3-(4-Fluorobenzyl)piperidine, SKU P708684. Aladdin Scientific official website.

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