Synthesis of novel chiral lipophilic pyridyl-containing β-amino alcohol ligands and enantioselective hydrolysis of α-amino acid esters by chiral metallomicelles

Abstract

Seven novel chiral lipophilic pyridyl-containing β-amino alcohol ligands have been synthesized by coupling of 6-alkoxymethyl-2-chloromethylpyridine 3 with the corresponding chiral β-amino alcohols or l-cysteine. Their metal ion complexes have been investigated as catalysts for the enantioselective hydrolysis of N-protected α-amino acid esters in aqueous comicellar solution. The results indicate that the hydrophobic interactions between substrate and metallocatalyst, the rigidity of the ligand, the hydroxyl group of the ligand acting as a nucleophile for the transacylation process, and the micellar microenvironment are important factors for the activity and enantioselectivity. Large rate accelerations (up to three orders of magnitude) and moderate enantioselectivities (up to 7.81 (k R/k S)) employing 4a–Cu 2+ have been observed.