title: Engaging Allene-Derived Zwitterions in an Unprecedented Mode of Asymmetric [3+2]-Annulation Reaction.
abstract: Catalytic addition of chiral phosphine, that is, (R)- or (S)-SITCP, to an α-substituted allene ester generated a zwitterionic dipole. Under optimized reaction conditions, this dipole could engage isatine-derived N-Boc-ketimines in a novel mode of [3+2] annulation reaction. Pyrrolinyl spirooxindoles are thus afforded in high yields and with excellent enantioselectivities. The unprecedented annulation reaction successfully facilitated the construction of sp(3) -rich and highly substituted 3,2'-pyrrolidinyl spirooxindoles supporting many chiral centers.
authors.affiliation: Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany.
authors.forename: Muthukumar G
authors.identifier: 0000-0002-8869-9041
authors.initials: MG
authors.lastname: Sankar
authors.affiliation: Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany.
authors.forename: Miguel
authors.initials: M
authors.lastname: Garcia-Castro
authors.affiliation: Fakultät Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, 44221, Dortmund, Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Golz
authors.affiliation: Fakultät Chemie und Chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Strasse 6, 44221, Dortmund, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Strohmann
authors.affiliation: Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Otto-Hahn-Strasse 11, 44227, Dortmund, Germany. kamal.kumar@mpi-dortmund.mpg.de.
authors.forename: Kamal
authors.identifier: 0000-0003-3593-8421
authors.initials: K
authors.lastname: Kumar
keywords: allenes; asymmetric synthesis; phosphine catalysis; spirooxindoles; zwitterions