Oxindole synthesis <i>via</i> polar–radical crossover of ketene-derived amide enolates in a formal [3 + 2] cycloaddition
作者:Niklas Radhoff、Armido Studer
DOI:10.1039/d1sc07134c
日期:——
and transition-metal free method for the preparation of valuable and sterically hindered 3,3-disubstituted oxindoles via polar–radical crossover of ketene derived amide enolates. Various easily accessible N-alkyl and N-arylanilines are added to disubstituted ketenes and the resulting amide enolates undergo upon single electron transfer oxidation a homolytic aromatic substitution (HAS) to provide 3,3-disubstituted
在此,我们介绍了一种简单、有效且不含过渡金属的方法,通过乙烯酮衍生的酰胺烯醇化物的极性-自由基交换来制备有价值的空间位阻3,3-二取代的羟吲哚。将各种容易获得的N-烷基和N-芳基苯胺添加到二取代乙烯酮中,所得酰胺烯醇化物在单电子转移氧化后经历均裂芳族取代 (HAS),以良好至优异的收率提供 3,3-二取代的羟吲哚。各种取代的苯胺和 3-氨基吡啶参与这种氧化形式的 [3 + 2] 环加成和环状烯酮提供螺吲哚。底物和试剂都很容易获得,并且对官能团的耐受性广泛。