The production of primary amines from aldehydes has been achieved without the need of protecting groups. Bridget Stocker and Mattie Timmer, Malaghan Institute of Medical Research and Victoria University of Wellington, New Zealand, report the synthesis is fast, efficient and applicable to a wide range of substrates.
The amines are produced via metal hydride amination of aldehydes or hemiacetals. The pH, number of amine equivalents, and concentration all influence the chemoselectivity. By optimizing the reaction, primary amines were selectively prepared with no or minimal formation of the usual secondary and tertiary amine by-product.
Optimal conditions require high pH, excess ammonia, and an aldehyde concentration of 20 mL of sat. NH4OAc in ethanol per mmol.
- Protecting-Group-Free Synthesis of Amines: Synthesis of Primary Amines from Aldehydes via Reductive Amination
E. M. Dangerfield, C. H. Plunkett, A. L. Win-Mason, B. L. Stocker, M. S. M. Timmer,
J. Org. Chem. 2010, 75.