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Enantioselective Michael Addition of Nitroalkanes to Nitroalkenes Catalyzed by Chiral Bifunctional Quinine-Based Squaramides

Tanyeli, Cihangir
A family of chiral bifunctional acid-/base-type quinine/squaramide organocatalysts is shown to be highly active promoters of the conjugate addition of 1-nitropropane to various trans--nitroalkenes. The cooperation of the quinine and the sterically encumbered squaramide moieties catalyzed the Michael addition reactions at 0 degrees C by using a catalyst loading of only 2mol% to afford the 1,3-dinitro Michael adducts with excellent enantioselectivity and diastereoselectivity (up to 95%ee and syn/anti isomers up to 96:4).