Synthesis Of New Azetidino Alcohol Ligands And Their Application In The Asymmetric Catalysis

Starting fromγ-butyrolactone, two pairs of novel ligands 6a-6d with three stereogenic centers were succesfully prepared. They were applied to the asymmetric addition reactions of alkynyl zinc to aldehydes. It was discussed that asymmetric conjugate addition reactions of diethylzinc to chalcone catalyzed by the ligands in our laboratory.1. The synthesis of novel chiral azetidino alcohol ligands with three stereogenic centers and their application in asymmetric alkynylation of aldehydesStarting fromγ-butyrolactone 1, two pairs of stereoisomers 6a,6d and 6b,6c were succesfully prepared via a five-step route. And these chiral ligands 6a-d were characterized by 1NMR,13CNMR, MS and IR. The specific rotation of these chiral compounds was recorded. At the same time, the absolute configuration of chiral ligand 6a was confirmed by X-ray single crystal diffraction.The catalytic activities and stereoselectivities of these chiral ligands were tested in asymmetric addition reactions of alkynylzinc to benzaldehyde. But when the reactions were catalyzed by chiral ligands 6a-d, poor enantioselectivities were obtained. With the optimal conditions, the best yield (90.1%) and enantioselectivity (33.1%) were achieved, so extended substrate can not be carried out.2. The application of chiral ferrocenyl ligands in the enantioselective conjugate addition reactions of diethylzinc to the chalcones.By screening the synthesized ligands of our laboratory, we found that the chiral aziridino alcohol ligands had better enantioselectivity, and the ligands were used in the catalyzed asymmetric congjugate addition reactions of diethylzinc to the chalcone, the chemical yield was obtained up to 82% and ee value as high as 87.6%. Though the in-depth study of the influence by R1 groups in the reactions, we found yields and enantioselectivities were improved significantly when R1 groups were methoxy group.