Modularly evolved 2-aminodmap/squaramides as highly active bifunctional organocatalysts in Michael addition
Özet
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 "uperbase" 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). © 2014 American Chemical Society.
Bağlantı
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84921315226&doi=10.1021%2fjo5022597&partnerID=40&md5=802730539f293db4d927bc730efe9feehttp://acikerisim.bingol.edu.tr/handle/20.500.12898/4759
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