Reductive
amination generates an important reaction in fine chemical
synthesis. The employment of water as the hydrogen donor for reductive
amination might solve the long-time hydrogen supply problem. Here,
we present our new results on reductive <i>N-</i>methylation
reactions of amine with paraformaldehyde with water as the co-hydrogen
donor catalyzed by a simple supported nanogold catalyst, i.e., Au/Al<sub>2</sub>O<sub>3</sub>. <i>N-</i>Methyl amines or <i>N</i>,<i>N</i>-dimethyl amines can be selectively
synthesized with excellent yields. Isotope tracing reactions confirmed
the transformation of hydrogen from water in the final product. In
addition, this method can be applied in the <i>N</i>-methylation
reactions of bioactive molecules with excellent performance. This
concept may supply a potential methodology for sustainable reductive
amination