Translating the Enantioselective Michael Reaction to a Continuous Flow Paradigm with an Immobilized, Fluorinated Organocatalyst

A novel polymer-supported fluorinated organo-catalyst has been prepared and benchmarked in the enantioselective Michael addition of aldehydes to nitroalkenes. The system has proven to be highly efficient and displays excellent selectivities (er and dr) with a wide variety of substrates. Detailed deactivation studies have given valuable insights, thus allowing the lifespan of this immobilized aminocatalyst to be significantly extended. These data have facilitated the implementation of enantioselective, continuous flow processes allowing either the multigram synthesis of a single Michael adduct over a 13 h period or the sequential generation of a library of enantiopure Michael adducts from different combinations of substrates (13 examples, 16 runs, 18.5 h total operation). A customized in-line aqueous workup, followed by liquid liquid separation in flow, allows for product isolation without the need of chromatography or other separation techniques.