Catalytic Dehydrogenation Strategies for Aromatic Amines

Catalytic dehydrogenation of saturated amine precursors has emerged as a powerful route to access aromatic amines under mild and environmentally benign conditions. By harnessing transition-metal catalysts or catalyst surrogates, cyclohexylamines, cyclohexanones and related substrates undergo sequential dehydrogenation, imine formation and aromatisation to furnish anilines, diarylamines and triarylamines with high atom economy. These acceptorless processes liberate molecular hydrogen as the sole by-product and avoid stoichiometric oxidants. Mechanistic studies reveal key steps such as β-hydride elimination from metal–amine intermediates, imine disproportionation and surface-assisted tautomerisation. Both heterogeneous nanoparticle systems and homogeneous ligand-stabilised complexes have been shown to promote dehydrogenative aromatisation with broad substrate scope, including symmetrical and unsymmetrical amines. The integration of relay catalysis, acid promoters and chain-walking isomerisation strategies has further expanded the diversity of accessible aromatic amines. Such methodologies address global challenges in sustainable synthesis by valorising biomass-derived feedstocks, generating hydrogen fuel and reducing waste, while delivering functional amines for pharmaceuticals, agrochemicals and advanced materials.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Catalytic Dehydrogenation Strategies for Aromatic Amines publication trend

The graph below shows the total number of articles in catalytic dehydrogenation strategies for aromatic amines across all publications each year (not limited to Nature Index journals).

Technical terms

Acceptorless dehydrogenative aromatisation: A catalytic transformation in which a saturated precursor is oxidised to an aromatic product without external oxidant, liberating H₂.

β-Hydride elimination: A step in metal–alkyl or metal–amine complexes where a hydrogen atom is transferred from the β-carbon to the metal centre, forming a double bond and a metal hydride.

Imine condensation: Formation of an imine by reaction of an amine with a carbonyl compound, often a key intermediate in dehydrogenative aromatisation.

Isoaromatization: A sequence in which a non-aromatic cyclic intermediate undergoes bond reorganisation and H₂ loss to yield an aromatic ring.

Relay catalysis: A multisite catalytic approach in which distinct catalyst components sequentially promote different steps of a reaction pathway, enhancing overall efficiency.

References

1. Versatile routes for synthesis of diarylamines through acceptorless dehydrogenative aromatization catalysis over supported gold–palladium bimetallic nanoparticles. Chemical Science (2017).
2. Synthesis of unsymmetrically substituted triarylamines via acceptorless dehydrogenative aromatization using a Pd/C and p -toluenesulfonic acid hybrid relay catalyst. Chemical Science (2020).
3. Synthesis of 2-benzyl N-substituted anilines via imine condensation–isoaromatization of (E)-2-arylidene-3-cyclohexenones and primary amines. Beilstein Journal of Organic Chemistry (2024).
4. (NHC)Pd(II) hydride-catalyzed dehydroaromatization by olefin chain-walking isomerization and transfer-dehydrogenation. Nature Communications (2022).