Designing Homogeneous Bromine Redox Catalysis for Selective Aliphatic C-H Bond Functionalization

Abstract

The potential of homogeneous oxidation catalysis employing bromine has remained largely unexplored. We herein show that the combination of a tetraalkylammonium bromide and meta-chloroperbenzoic acid offers a unique catalyst system for the convenient and selective oxidation of saturated C(sp³ )-H bonds upon photochemical initiation with day light. This approach enables remote, intramolecular, position-selective C-H amination as demonstrated for 20 different examples. For the first time, an N-halogenated intermediate was isolated as the active catalyst state in a catalytic Hofmann-Löffler reaction. In addition, an expeditious one-pot synthesis of N-sulfonyl oxaziridines from N-sulfonamides was developed and exemplified for 15 transformations. These pioneering examples provide a change in paradigm for molecular catalysis with bromine.

Keywords: C−H functionalization; Hofmann-Löffler reaction; amination; bromine; catalysis.