Enantioselective Olefin Epoxidation Using Novel Doubly Bridged Biphenyl Azepines as Catalysts

Abstract

Enantiopure (diastereomeric) doubly bridged biphenyl azepines prepared from (S)-3,3-dimethylbutan-2-amine and (S)-1-phenylpropylamine can be – as a function of the exocyclic side chain – either effective catalysts for the enantioselective epoxidation of unfunctionalized olefins or no catalysts at all. In the case of the (S)-1-phenylpropylamine derivative, an unwanted and unexpected Cope elimination derails the catalytic reactivity which can, however, be recovered by the addition of NBS prior to that of the substrate and other reagents.

Keywords

• Atropisomers
• Catalysis
• Chiral amines
• Chirality
• Cope elimination
• Epoxidation