Fluorinated chiral secondary amines as catalysts for epoxidation of olefins with oxone

Abstract

(Chemical Equation Presented) We have synthesized a series of chiral cyclic secondary amines having different substitution patterns and have screened them as catalysts for the asymmetric epoxidation of olefins using Oxone. The highest enantiomeric excess (61%) occurred for the epoxidation of 1-phenylcyclohexene catalyzed by a secondary amine bearing a fluorine atom at the β-position relative to the amino center. Our experimental results provide further support to the notion that the amine plays a dual role - as a phase transfer catalyst and an Oxone activator - in these epoxidation reactions. The slightly acidic reaction conditions we employed in this work obviate the need to preform ammonium salts, which are the actual catalysts that mediate the epoxidations.