Synthesis of calix[4]arene derivatives bearing chiral pendant groups as ligands for enantioselective catalysis

Abstract

New chiral calix[4]arene derivatives have been synthesized by appending at the lower rim amino acid (L-tyrosine, L-aspartic, acid, L-valine, and L-tryptophan) or pinene-like (myrtenyl and homomyrtenyl) units or by distal intrabridging with a binaphthyl amine scaffold. The application of these derivatives in enantioselective catalysis was studied by testing the catalytic activities of the corresponding Ti(IV)/calixarene complexes, prepared in situ, in the asymmetric aldol reaction of Chans silyloxydiene with p-nitrobenzaldehyde