Ni(II)-Catalyzed Enantioselective Addition of Thiols and Thiophenols to Pyrazolinone-Derived Ketimines

Abstract

Enantioselective additions of thiols and thiophenols to pyrazolinone-derived ketimines were realized using a Ni(II) complex bearing a tridentate binaphthyl-proline-imidazoline-based chiral ligand as the catalyst. The well-defined confined environment of the catalyst enabled the stereofacial selective activation of the electrophiles, and the products were obtained in up to 99% yield with 99% ee. The reactions featured low catalyst loading, mild conditions, broad substrate scope, and gram-scale utility. X-ray diffraction experiments confirmed both the configuration of the C═N double bond and the absolute configuration of the products, and stereofacial selection of the reactions was deduced accordingly.