A general catalyst for the base-free mono-N-alkylation of aromatic and aliphatic amines with alcohols

The catalytic alkylation of amines with alcohols is a highly atom-economical approach that produces water as the sole by-product. Existing catalytic systems lack generality and are primarily applicable to electron-poor amines or to non-oxidizable amines, such as anilines. The outstanding effectiveness of an Ir-NHC catalyst in forming C−N bonds from alcohols and amines, both aliphatic and aromatic, is presented here. The catalyst performs remarkably under mild conditions, even at room temperature, attaining complete selectivity in all tested cases toward monoalkylation, even for challenging aliphatic amines, and under base-free conditions. Thorough mechanistic investigation to understand the outstanding activity and selectivity, combining experimental, theoretical, and both in situ and ex situ X-ray absorption spectroscopy (XAS) studies, are presented.