Catalytic Performance of Chiral Tetraaza-Bridged Calix[4]arene[2]triazine Derivatives for Enantioselective Michael Reactions

Novel chiral tetraaza-bridged calix[4]arene[2]triazine-based organocatalysts were synthesized and used for catalytic asymmetric Michael reaction of acetylacetone to various aromatic nitrostyrenes. Chiral subunits (R)- and (S)-1,2,3,4-tetrahydro-1-naphthylamine were attached to the tetraaza-bridged calix[4]arene[2]triazine platform in both enantiomeric forms. The R configuration of the major enantiomer of the Michael product was obtained when 3a was used as catalyst, and the S configuration was obtained when 3b was used as catalyst. This indicated that the configuration of the Michael product was controlled by the chiral calixarene moiety. The Michael adducts were obtained in excellent yields (91%) and enantioselectivities (98%).