Synthesis And Application Of Chiral Aziridino Alcohol Ligands And Immobilized Chiral Ligands

A series of chiral aziridino alcohol ligands and immobilized chiral ligands were synthesized and applied to catalytic asymmetric addition of dimethylzinc or diethylzinc to aldehydes, achieving excellent results, recycling and reuse of the immobilized chiral ligands.1. The synthesis of chiral aziridino alcohol ligands and their application in the catalytic asymmetric addition of diethylzinc to aldehydesChiral ligands2-6were prepared from easily available L-serine2-1by esterification, codensation, reductive amination, cyclization, and then treatment with RMgX. All the compounds were characterized by1H NMR,13C NMR, IR, and HRMS. The specific rotation of compounds were recorded. The chiral ligands2-6catalyzed the asymmetric addition of diethylzinc to aldehydes, giving the corresponding products up to97.0%yield with98.3%enantiomeric excess.2. Synthesis of MeO-PEG-supported ferrocenyloxazoline ligand and its application in asymmetric catalysisChiral ligand3-6was prepared from cheap and readily available L-tyrosine3-1by esterification, protection of amino group, phenolic hydroxyl protection, reduction, removal of the Boc.3-8was synthesized from ferrocene carboxylic acid and amino alcohol3-6, then by lithiation, removal of the TBS, followed by reaction with poly(ethylene glycol)s2000monomethyl ether mesylate in the presence of CS2CO3in DMF, giving the PEG supported chiral ligand3-12. The ligand catalyzed the asymmetric addition of diethylzinc to aldehydes, affording corresponding products with up to99.0%yield and93.5%enantiomeric excess. The MeO-PEG-supported ferrocenyloxazoline ligand can be recycling and reuse.3. The application of chiral dendrimers supported N-ferrocenylmethyl aziridino alcohol ligands in the catalytic asymmetric addition of dimethylzinc to aldehydesChiral ligand4-1catalyzed the asymmetric addition of dimethylzinc to aldehydes giving the corresponding products with94.9%enantiomeric excess. By replacement of the ligand4-2, up to96.9%enantiomeric excess can be obtained. Furthermore, the ligand4-2also preserved excellent stereo selectivity after recycled three times.