Amines

The amine functional group is the most prevalent nitrogen-containing feature across approved drugs, present in over 70% of small-molecule pharmaceuticals in a primary, secondary, or tertiary form. Its ability to act as both a hydrogen bond donor and acceptor, engage in ionic interactions with aspartate and glutamate residues in protein binding sites, and adopt a range of geometries from planar (anilines) to pyramidal (alkylamines) makes it one of the most versatile pharmacophoric elements in drug design. The ionisation state of an amine is governed by its pKa, which in turn determines membrane permeability, plasma protein binding, volume of distribution, and the balance between charged and neutral species at physiological pH. Saturated aliphatic amines, including piperidines, piperazines, morpholines, and pyrrolidines, are among the most frequently encountered ring systems in drugs targeting CNS, oncology, and infectious disease indications, contributing to solubility, metabolic stability, and three-dimensional shape. Aromatic amines and anilines, while metabolically vulnerable to oxidation to reactive quinone-imine intermediates, are retained selectively in drug scaffolds where their electronic contribution to binding affinity is essential and the metabolic risk is managed by structural modification. The primary amine, as a strong hydrogen bond donor, is particularly valued in fragment-based drug discovery and in the design of covalent inhibitors, where it serves as a nucleophilic warhead or as a directional anchor within constrained binding sites. Cyclic amines are also exploited as basic centres to improve aqueous solubility and oral bioavailability, and the choice of ring size and substitution pattern is a key variable in lead optimisation. The amine group remains among the richest areas for exploration in medicinal chemistry, with significant opportunities in underexplored amine subclasses including azetidines, spirocyclic amines, and primary aryl amines.

Two first-in-class FDA-approved drugs from 2023 and 2025 illustrate the pharmacological centrality of the amine functional group. Capivasertib (Truqap, AstraZeneca), the first-in-class pan-AKT inhibitor approved in November 2023 for the treatment of PIK3CA/AKT1/PTEN-altered hormone receptor-positive, HER2-negative advanced breast cancer, incorporates a 4-aminopiperidine group as a key structural element. The primary amine on the piperidine ring forms hydrogen bonds with the hinge region of the AKT kinase domain and contributes to the compound's selectivity profile across AKT isoforms through its interaction with the glycine-rich loop. Suzetrigine (Journavx, Vertex Pharmaceuticals), the first-in-class selective NaV1.8 inhibitor approved in January 2025 for the treatment of moderate-to-severe acute pain, is the first new class of analgesic approved in over two decades. It incorporates a primary carboxamide (pyridine-2-carboxamide, −CONH2) and a secondary amide linkage whose N-H hydrogen bonds engage directly with the unique KKGS motif in the second voltage-sensing domain (VSD2) of NaV1.8, a binding configuration that accounts for both its exceptional potency and its selectivity over the closely related NaV1.5 cardiac channel.

In organic synthesis, amines are central to a broad range of fundamental named reactions. Reductive amination, condensation of a primary or secondary amine with an aldehyde or ketone followed by reduction with sodium cyanoborohydride or sodium triacetoxyborohydride, is one of the most widely used C-N bond-forming reactions in pharmaceutical synthesis. The Buchwald-Hartwig amination, palladium-catalysed coupling of amines with aryl halides using biaryl phosphine ligands, is the premier method for the synthesis of diaryl and aryl-alkyl amines in drug discovery. The Gabriel synthesis converts primary alkyl halides to primary amines via phthalimide intermediates, providing a clean route to unprotected primary amines without overalkylation. The Leimgruber-Batcho synthesis provides access to indoles from nitrotoluenes via enamine intermediates, and the Ullmann condensation enables copper-catalysed aryl C-N bond formation. The Mannich reaction condenses primary or secondary amines with formaldehyde and a carbon nucleophile to produce beta-amino carbonyl compounds, providing rapid routes to aminomethylated drug-like scaffolds.

Emerging synthetic techniques are rapidly expanding the scope of amine chemistry. In photochemistry, visible-light photoredox catalysis has enabled the generation of aminium radical cations from tertiary amines under mild oxidative conditions, providing access to alpha-amino radicals that participate in intermolecular C-C bond forming additions to Michael acceptors, in alpha-functionalisation cascades, and in direct C-H amination of electron-rich arenes. Deaminative functionalisations using Katritzky pyridinium salts as amine surrogates have opened new radical disconnections from primary and secondary amines under photoredox conditions, converting them to alkyl radical precursors. Electrochemically, anodic oxidation of amines generates nitrogen-centred and alpha-carbon radicals, enabling direct alpha-C-H functionalisations, intramolecular C-H amination to access azetidines and pyrrolidines, and oxidative C-N coupling reactions without stoichiometric external oxidants. These methods are particularly valuable for the preparation of the saturated nitrogen heterocycles that are increasingly prioritised in modern drug discovery, providing sustainable and scalable routes to building blocks previously inaccessible without lengthy multi-step sequences.

Our catalogue of amines spans a broad range of primary, secondary, and tertiary aliphatic, aryl, and heterocyclic structures.