title: Construction of Optically Active Quaternary Propargyl Amines by Highly Enantioselective Zinc/BINOL-Catalyzed Alkynylation of Ketoimines.
abstract: A general and efficient method for the highly enantioselective alkynylation of ketoimines through a zinc/1,1'-bi-2-naphthol (BINOL)-catalyzed process has been developed. A variety of ketoimines, including α-fluoroalkyl α-imine esters, α-aryl α-imine esters, and trifluoromethyl aryl ketoimines, are applicable and provide their corresponding quaternary propargyl amines in excellent yields with high ee values (up to 99 % ee). Both the steric and electronic effects of substituents at the 3,3' positions of BINOL are critical for the reaction efficiency and enantioselectivity. To demonstrate the usefulness of the method, (R)-α-CF3 α-proline has been prepared in a highly efficient manner. The notable features of this protocol are its broad substrate scope, high reaction efficiency (up to 99 %) and enantioselectivity (up to 99 % ee), low catalyst loading (5 mol % of BINOL derivative), and mild reaction conditions.
authors.affiliation: Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032 (P.R. China).
authors.forename: Gaochao
authors.initials: G
authors.lastname: Huang
authors.forename: Zengsheng
authors.initials: Z
authors.lastname: Yin
authors.forename: Xingang
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D007097:Imines / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D009284:Naphthols / Q000737:chemistry*; D013237:Stereoisomerism; D015032:Zinc / Q000737:chemistry*
chemical_list: D000480:Alkynes; D000588:Amines; D007097:Imines; D007659:Ketones; D009284:Naphthols; C412332:1,1'-bi-2-naphthol; D015032:Zinc
keywords: BINOL; alkynylation; amino acids; ketoimines; propargyl amines; zinc