Synthesis Of Aza-Semi-Crown-Ether Chiral Ligands And The Application In The Asymmetric Ehtylation Of Aldehydes

In this thesis, two kinds of enantiopure aza-semi-crown-ether chiral ligands were designed and synthesized from readily available natural amino acids. The preliminary studies on the aza-semi-crown-ether chiral ligand possessing C₂-symmetrical two central chirality were carried out for the application in the asymmetric addition of diethylzinc to aldehydes.1. The synthesis of aza-semi-crown-ether chiral ligand with C₂-symmetrical two central chirality and its preliminary application in the asymmetric catalysisChiral ligand 7 was prepared from easily available L-serine 1 by the esterification, Trt-protection, cyclization, treatment with RMgX, deprotection, then condensation with 2,6-bis(bromomethyl)cresol. And it was characterized by ¹HNMR, ¹³CNMR, IR, MS. The specific rotation was recorded.The chiral ligand 7 was used as catalyst to promote the asymmetric addition of diethylzinc to arylaldehydes affording the corresponding 1-aryl-1-propanol in up to 86.1% enantiomenc excess with high to excellent yields (up to 100%).2. The synthesis of aza-semi-crown-ether chiral ligand with C₂-symmetrical four central chiralityStarting from essily available L-threonine, another chiral ligand 14 was prepared by the similar route of 7. And it was also characterized by ¹HNMR, ¹³CNMR, IR, MS. The specific rotation was recorded.