title: Modularly evolved 2-aminoDMAP/squaramides as highly active bifunctional organocatalysts in Michael addition.
abstract: We report a new family of chiral bifunctional acid/base type organocatalysts, 2-aminoDMAP/Squaramides, which are proved to be highly active (1 mol % cat. loading) promoters in conjugate addition of dibenzoylmethane to various trans-β-nitroalkenes. Steric demand of the catalysts was clearly seen by a set-by-set modulation of the squaramide unit through electronic and steric factors. The synergistic cooperation of 2-aminoDMAP “superbase” and sterically encumbered squaramide (H-bond donor) enabled complete conversion of a range of reactants into corresponding Michael adducts in a couple of hours with exquisite selectivities (up to 98% ee).
authors.forename: Murat
authors.initials: M
authors.lastname: Işık
authors.forename: M Yagiz
authors.initials: MY
authors.lastname: Unver
authors.forename: Cihangir
authors.initials: C
authors.lastname: Tanyeli