Catalytic Asymmetric 1,3-Dipolar Cycloaddition of β-Fluoroalkylated α,β-Unsaturated 2-Pyridylsulfones with Nitrones for Chiral Fluoroalkylated Isoxazolidines and γ-Amino Alcohols

详细信息    查看全文

• 作者：Xing Yang ; Feng Cheng ; Ying-Da Kou ; Shuai Pang ; Yong-Cun Shen ; Prof. Dr. Yi-Yong Huang and Prof. Dr. Norio Shibata
• 刊名：Angewandte Chemie
• 出版年：2017
• 出版时间：February 1, 2017
• 年：2017
• 卷：129
• 期：6
• 页码：1532-1536
• 全文大小：712K
• ISSN：1521-3757

文摘

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 Ni^II/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.