Highly Enantioselective Rh-Catalyzed Alkenylation of Imines: Synthesis of Chiral Allylic Amines via Asymmetric Addition of Potassium Alkenyltrifluoroborates to <i>N</i>-Tosyl Imines

Abstract

For the first time, simple N-tosyl aryl aldimines, prepared from the condensation of tosyl amide and aromatic aldehydes, can be used as substrates in the rhodium catalyzed 1,2-addition reaction using alkenylboron nucleophiles. In the presence of 1.5 mol % of [RhCl(1e)]2, enantioselective addition of various potassium alkenyltrifluoroborates to aryl aldimines furnished the corresponding chiral allylic amines in 73-96% yield and 72->99.5% ee. Notably, this method efficiently provides the di-, tri-, and tetrasubstituted allylic N-tosyl amines with high asymmetric induction.