Halogen Radical-Enabled Dearomatization of <i>N</i>-Arylpropiolamides via Photoinduced Sequential Halogenation/Spirocyclization/Oxidation Process

Here we report a strategy that eliminates the need for photocatalysts and external additives, which provides an operable and mild method for halogen radical-enabled dearomatization of <i>N</i>-arylpropiolamides under an oxygen atmosphere at room temperature. The method is applicable to a wide range of substrates, extending beyond the limited scope of <i>p</i>-methoxyl <i>N</i>-phenylpropynamides. Furthermore, several functional synthetic intermediates and anticancer bioactive molecules were successfully derived from 3-halogenated azaspiro[4.5]trienones.