title: Enantioselective synthesis of chiral heterocycles containing both chroman and pyrazolone derivatives catalysed by a chiral squaramide.
abstract: An efficient chiral squaramide-catalysed enantioselective Michael addition of pyrazolin-5-ones to 3-nitro-2H-chromenes for the synthesis of chiral heterocyclic systems containing both chroman and pyrazolone derivatives has been developed. This reaction afforded the desired products in high to excellent yields (up to 98%) with high enantioselectivities (up to 96%) and excellent diastereoselectivities (up to 99 : 1) under very low catalyst loading (0.2 mol%). This catalytic asymmetric reaction provides an efficient route toward the synthesis of chiral heterocyclic systems containing both chroman and pyrazolone derivatives, which possess potential pharmaceutical activities.
authors.affiliation: School of Chemical Engineering and Environment, Beijing Institute of Technology, Beijing 100081, People's Republic of China. dudm@bit.edu.cn.
authors.forename: Jun-Hua
authors.initials: JH
authors.lastname: Li
authors.forename: Da-Ming
authors.initials: DM
authors.lastname: Du
mesh_terms: D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D002839:Chromans / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000138:chemical synthesis*; D008958:Models, Molecular; D015394:Molecular Structure; D047069:Pyrazolones / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000577:Amides; D002839:Chromans; D006571:Heterocyclic Compounds; D047069:Pyrazolones