Immobilization And Application Of Chiral Ferrocenyl Oxazoline Ligands

In this thesis, author conducted the study of the synthesis and immobilization of chiral ferrocenyl oxazoline ligands. Author has synthetized and resoluted two ferrocenyl oxazoline ligands. both of which were simultaneously possessing planer and central chirality. Then the application of these two diastereoisomerical two ferrocenyl oxazoline ligands in catalytic asymmetric addition of diethylzinc to aromatic aldehydes was investigated.1. Synthesis of chiral ferrocenyl oxazoline ligandsPhenolic hydroxyl group protected β-aminoalcohol, a key intermediate, was prepared from cheap and readily available L-tyrosine as the raw material, by steps of esterification, amino protection, the protection of the phenolic hydroxyl, ester reduction and amino deprotection. And then the phenolic hydroxyl group protected β-amino alcohols reacted with ferrocene chloride and then cyclized forming the oxazolines. Ferrocenyl oxazoline, which phenolic hydroxyl was protected (immobilized) by benzyl, was reacted with benzophenone after treated with butyl lithium to generate [G-0] ferrocenyl oxazoline chiral N,O ligands, which simultaneously possessing planer and central chirality. The ratio of two diastereoisomers was determined by chiral HPLC. The two diastereoisomers resoluted in mechanical method by recrystallization with hexane as solvent. The purity of each diastereoisomer was greater than99.5%. The synthesis of TBS protected ferrocenyl oxazoline laid the foundation of preparing higher generation dendrimer immobilized ferrocenyl oxazoline chiral N,O ligands.2. Application of [G-0] ferrocenyl oxazoline chiral ligands in the catalytic diethylzinc asymmetric addition to aromatic aldehydesThe two resoluted diastereoisomers were respectively applied to catalytic diethylzinc asymmetric addition to aromatic aldehydes. Ligand11obtained good results (>99%yield,86%ee), and ligand12obtained a good yield with moderate enantioselectivity (>99%yield,57%ee).