Amination

Amination is a chemical process that introduces an amine group into an organic molecule, forming C–N bonds. It encompasses methods that install primary, secondary, or tertiary amines and applies to substrates such as carbonyl compounds, alkenes, alkynes, and certain C–H bonds.

Reductive amination is among the most widely used approaches. Aldehydes or ketones react with ammonia or primary/secondary amines to form imines or iminium ions, which are then reduced to the corresponding amines. Common reducing agents include sodium cyanoborohydride, borohydride reagents, or catalytic hydrogenation. This method provides a flexible route to diverse amines under relatively mild conditions.

Hydroamination refers to the direct addition of an N–H bond across a carbon–carbon multiple bond, yielding secondary or tertiary amines. This transformation can proceed under metal catalysis (often with transition metals) or with radical/photochemical conditions, enabling the conversion of alkenes or alkynes into amines in a single step.

Direct C–H amination involves converting a carbon–hydrogen bond directly into a carbon–nitrogen bond, typically using catalysts and directing groups to achieve site selectivity. This area is particularly active for late-stage functionalization in complex molecules.

Electrophilic and nucleophilic amination describe transfers of nitrogen from amine-equivalent sources to substrates, expanding the repertoire of C–N bond-forming strategies for arenes, heterocycles, and other platforms.

Applications of amination include the synthesis of pharmaceuticals, agrochemicals, and polymers, and the preparation of various primary, secondary, and tertiary amines. Challenges include achieving chemoselectivity, controlling over-alkylation, and managing sensitive reagents, with ongoing research aimed at more sustainable and efficient catalysts and methods.