Platinum-Catalyzed, Terminal-Selective C(sp3)–H Oxidation of Aliphatic Amines

http://pubs.acs.org/doi/abs/10.1021/jacs.5b09099

Platinum-Catalyzed, Terminal-Selective C(sp³)–H Oxidation of Aliphatic Amines

Melissa Lee and Melanie S. Sanford^*

Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/jacs.5b09099

Publication Date (Web): October 6, 2015

Copyright © 2015 American Chemical Society

Abstract

This Communication describes the terminal-selective, Pt-catalyzed C(sp³)–H oxidation of aliphatic amines without the requirement for directing groups. CuCl₂ is employed as a stoichiometric oxidant, and the reactions proceed in high yield at Pt loadings as low as 1 mol%. These transformations are conducted in the presence of sulfuric acid, which reacts with the amine substrates in situ to form ammonium salts. We propose that protonation of the amine serves at least three important roles: (i) it renders the substrates soluble in the aqueous reaction medium; (ii) it limits binding of the amine nitrogen to Pt or Cu; and (iii) it electronically deactivates the C–H bonds proximal to the nitrogen center. We demonstrate that this strategy is effective for the terminal-selective C(sp³)–H oxidation of a variety of primary, secondary, and tertiary amines.