Highly Enantioselective Michael Additions of Isobutyraldehyde to Nitroalkenes Promoted by Amphiphilic Bifunctional Primary Amine‐Thioureas in Organic or Aqueous Medium

Abstract

Abstract A novel class of chiral amphiphilic bifunctional thioureas based on a beyerane scaffold and each containing a primary amino group were designed and synthesized from the readily available natural product isosteviol. The thioureas were shown to be effective for catalyzing asymmetric Michael additions between isobutyraldehyde and nitroalkenes. The chiral thiourea 1a furnished S enantiomers, whereas 1b afforded R enantiomers, both with high yields (up to 92 %) and high to excellent enantioselectivities (up to 98 %). Furthermore, the reactions proceeded smoothly both in organic solvents and in water under mild conditions.