Norbornanoid Chiral Ketones by Desymmetrization of Dibromoalkenes

Abstract

AbstractNew optically active polycyclic ketones 6a–6d, amenable to a large variety of synthetic applications, have been prepared from readily available 2,3‐dibromonorbornene and analogs (Scheme 2) via desymmetrization with (−)‐ephedrine, followed by hydrolysis under mild acidic conditions. At variance with substrates 4a–4d, the sterically hindered norbornene derivative 4e reacts with the solvent N‐methylpyrrolidin‐2‐one (NMP) leading to the formation of the unusual cyclopropanoid products 8a and 8b.