SPSiP-Enabled Pd-Catalyzed Enantioselective Alkynylamination of Alkenes

Here, we reported the first example of enantioselective Pd-catalyzed intramolecular alkynylamination of alkenes enabled by the development of a novel SPSiP ligand using alkynyl bromides as the C(sp)-electrophile. This ligand-enabled protocol allows the efficient synthesis of chiral pyrrolidine derivatives at room temperature in moderate to high yields (up to 92% yield) and high enantioselectivities (up to 95.5:4.5 er). Mechanistic and computational studies unveiled the high reactivity and enantioselectivity might originate from the electron-rich nature and large bite angle in the SPSiP ligand. The synthetic values of this reaction are demonstrated by various transformations and efficient synthesis of phenanthroindolizidine alkaloids including (+)-antofine and (+)-ficuseptine.