Alicyclic‐Amine‐Derived Imine‐BF3 Complexes: Easy‐to‐Make Building Blocks for the Synthesis of Valuable α‐Functionalized Azacycles

Abstract

AbstractA new strategy to access α‐functionalized alicyclic amines via their corresponding imine‐BF3 complexes is reported. Isolable imine‐BF3 complexes, readily prepared via dehydrohalogenation of N‐bromoamines in a base‐promoted/18‐crown‐6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α‐functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions. In situ preparation of imine‐BF3 complexes provides access to α‐functionalized morpholines and piperazines directly from their parent amines in a single operation. α‐Functionalized morpholines can be elaborated further, for instance by installing a second substituent in the α′‐position.