<i>syn</i>‐Selective Asymmetric Mannich Reaction of Sulfonyl Imines with Iminoesters Catalyzed by the <i>N</i>,<i>N</i>,<i>N</i>‐Tridentate Bis(imidazolidine)pyridine (PyBidine)–Cu(OTf)₂ Complex

Abstract

Chiral ligand: The [PyBidine–Cu(OTf)2] (Tf=trifluoromethanesulfonate) complex catalyzed the asymmetric Mannich reaction of sulfonyl imines 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).