title: Catalytic Asymmetric 1,3-Dipolar Cycloaddition of β-Fluoroalkylated α,β-Unsaturated 2-Pyridylsulfones with Nitrones for Chiral Fluoroalkylated Isoxazolidines and γ-Amino Alcohols.
abstract: 2-Pyridylsulfone- and fluoroalkylated group-activated olefins underwent highly efficient diastereo- and enantioselective 1,3-dipolar cycloadditions across various aromatic and aliphatic nitrones in the presence of a chiral NiII/bis(oxazoline) catalyst. The process was tuned by 4 Å molecular sieves, chiral bis(oxazoline) ligands, reaction solvents, and temperature. A wide array of optically pure fluoroalkylated isoxazolidines were obtained, thus facilitating the asymmetric synthesis of an enantioenriched α-trifluoromethylated γ-amino alcohol in gram-scale and a trifluoromethylated derivative of 1,3-oxazinan-2-one with potential pharmaceutical interest. A stereochemical model, based on the absolute configuration of one adduct and some control experiments, was postulated to account for the observed endo- and enantioselectivity.
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Xing
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Cheng
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Ying-Da
authors.initials: YD
authors.lastname: Kou
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Pang
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Yong-Cun
authors.initials: YC
authors.lastname: Shen
authors.affiliation: Department of Chemistry, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan, 430070, P.R. China.
authors.forename: Yi-Yong
authors.initials: YY
authors.lastname: Huang
authors.affiliation: Department of Nanopharmaceutical Sciences, Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya, 466-8555, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Shibata
keywords: asymmetric cycloaddition; fluoroalkylation; isoxazolidines; nitrones; γ-amino alcohols