Palladium-Catalyzed Asymmetric (4 + 2) Annulation of γ-Methylidene-δ-valerolactones with Alkenes: Enantioselective Synthesis of Functionalized Chiral Cyclohexyl Spirooxindoles.
有机化学
组合化学
环加成
作者
Zhi-Long Jia,Xian-Tao An,Yu-Hua Deng,Lin-Han Pang,Chun-Fang Liu,Le-Le Meng,Jia-Kun Xue,Xian-He Zhao,Chun-An Fan
出处
期刊:Organic Letters [American Chemical Society] 日期:2021-01-21卷期号:23 (3): 745-750被引量:10
标识
DOI:10.1021/acs.orglett.0c03963
摘要
An unprecedented asymmetric catalytic (4 + 2) annulation reaction of aryl-substituted γ-methylidene-δ-valerolactones (GMDVs) with isatin-derived para-quinone methides (p-QMs) has been developed under the catalysis of palladium(0) and (S,S,S)-(-)-Xyl-SKP, offering a new approach for the diastereo- and enantioselective synthesis of chiral cyclohexadienone-fused cyclohexyl spirooxindoles. Significantly, three highly congested contiguous tetrasubstituted carbon atoms embedded in bispirocyclic skeleton, of which two are vicinal quaternary stereogenic centers, are forged in an effective and selective manner (up to 99% yield, up to 95% ee, >20/1 dr). The current reaction represents the first exploration of enantioselective catalytic (4 + 2) annulation forming the six-membered carbocycles in the chemistry of both GMDVs and p-QMs.