Synthesis of new β-hydroxy amide ligands and their Ti(IV) complex-catalyzed enantioselective alkynylation of aliphatic and vinyl aldehydes

Three new chiral β-hydroxy amide ligands were synthesized via the reaction of benzyl chloride and amino alcohols derived from l-tyrosine. The titanium(IV) complex of chiral ligand 8b was found to be an effective catalyst for the asymmetric alkynylation of aliphatic, vinyl and aromatic aldehydes. The propargyl alcohols were obtained in highly enantiomeric excesses (up to 96% ee) under optimized conditions.