# Ligand-free reductive amination via Pd-coated mechanocatalysis

## TL;DR

A new method for reductive amination uses mechanical milling with palladium to produce amines efficiently without needing a ligand.

## Contribution

A sequential two-frequency milling protocol enables ligand-free reductive amination with high amine yields.

## Key findings

- A sequential two-frequency milling protocol separates imine formation and hydrogenation.
- Hydrophobic additives enhance reaction efficiency by excluding water.
- The method achieves up to 88% amine yields and works with various substrates.

## Abstract

Reductive amination under direct mechanocatalysis was enabled by a sequential two-frequency milling protocol, separating imine formation and hydrogenation. Strongly hydrophobic liquid additives accelerated the reaction by enhancing water exclusion. This approach allowed amine yields of up to 88% and was applicable to various aldehydes, ketones, and primary or secondary amines.

Reductive amination under direct mechanocatalysis was enabled by a sequential two-frequency milling protocol, separating imine formation and hydrogenation.