title: 4-Substituted-alpha,alpha-diaryl-prolinols improve the enantioselective catalytic epoxidation of alpha,beta-enones.
abstract: To seek novel metal-free organic catalysts for epoxidation with high stereoselectivity, a series of 4-substituted-alpha,alpha-diaryl-prolinols were synthesized in four steps from trans-4-hydroxyl-L-proline. These prolinol derivatives catalyzed the asymmetric epoxidation of alpha,beta-enones to give the corresponding chiral epoxides in good yields and high enantioselectivities under mild reaction conditions. Studies of substituent effects on enantioselectivity revealed that steric bulk and electronic effect promoted higher enantioselectivity, and prolinol 8a was found to be the best catalyst until now.
authors.affiliation: Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Yawen
authors.initials: Y
authors.lastname: Li
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Liu
authors.forename: Yingquan
authors.initials: Y
authors.lastname: Yang
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
mesh_terms: D002384:Catalysis; D004852:Epoxy Compounds / Q000737:chemistry*; D015394:Molecular Structure; D011759:Pyrrolidines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D004852:Epoxy Compounds; D011759:Pyrrolidines; C010509:prolinol