syn-Selective Asymmetric Mannich Reaction of Sulfonyl Imines with Iminoesters Catalyzed by the N,N,N-Tridentate Bis(imidazolidine)pyridine (PyBidine)-Cu(OTf)2 Complex
Chiral ligand: The [PyBidine–Cu(OTf)2] (Tf=trifluoromethanesulfonate) complexcatalyzed the asymmetricMannichreaction of sulfonylimines and iminoesters to give the products in a high syn‐selective manner. For both 4‐toluene (Ts)‐ and 4‐nitrophenylsulfonyl (Ns)‐imines, the syn‐adducts were obtained in up to 99 % ee (see scheme).