Asymmetric Michael Addition of 2-Acetyl Azaarenes to beta-CF3-beta-(3-indolyl)nitroalkenes Catalyzed by a Cobalt(II)/(imidazoline-oxazoline) Complex

摘要

The first enantioselective Michael addition of 2-acetyl azaarenes to beta-CF3-beta-(3-indolyl)nitroalkenes has been successfully achieved in the presence of a Co(II)/(imidazoline-oxazoline) complex as the catalyst. The reaction affords a series of CF3- and 3-indole-containing adducts featuring a trifluoromethylated all-carbon quaternary stereocenter in good to excellent yields (up to 99%) and enantioselectivities (up to 96% ee). Furthermore, the functional groups in the adducts including C=O, NO2, and the azaarene provide a large variety of useful transformations, leading to the formation of valuable intermediates such as optically active secondary alcohol, pyrroline, ester, and pyrrolidinone which all contain a 3-substituted indole and a trifluoromethylated all-carbon quaternary stereocenter.