Catalytic Asymmetric Tandem Cycloisomerization/[5+2] Cycloaddition Reaction of <i>N</i>-Aryl Nitrone Alkynes with Methyleneindolinones
作者:Bowen Hu、Xiying Zhang、Yuhao Mo、Jinzhao Li、LiLi Lin、Xiaohua Liu、Xiaoming Feng
DOI:10.1021/acs.orglett.9b04572
日期:2020.2.7
cycloisomerization and intermolecular [5+2] cycloaddition reaction of 2-ethynylphenyl-substituted nitrones with methyleneindolinones was realized. The process includes the palladium(II)-promoted in situ formation of azomethine ylide and the following chiral N,N'-dioxide-Co(II) complex-catalyzed regio-, diastereo-, and enantioselective [5+2] cycloaddition reaction. The desired spiro-tropanyl oxindoles were obtained
实现了2-乙炔基苯基取代的亚硝基与亚甲基吲哚满酮的不对称串联环异构化和分子间[5 + 2]环加成反应。该方法包括钯(II)促进原位形成的甲亚胺叶立德和随后的手性N,N'-二氧化物-Co(II)络合物催化的区域,非对映和对映选择性[5 + 2]环加成反应。以良好的收率和优异的dr和ee值获得了所需的螺-tropanyl羟吲哚。在确定催化剂结构的基础上,提出了可能的过渡态模型。