Merging Photoredox Catalysis with Iron(III) Catalysis: C5-H Bromination and Iodination of 8-Aminoquinoline Amides in Water

摘要

A simple and efficient protocol for the iron(III)-catalyzed C5 halogenation of 8-aminoquinoline with potassium halides via a photoredox process was developed, affording desired products in good to excellent yields. This reaction features its mild and green conditions (proceeding in water under air at room temperature). Electronic effect is not obvious in this reaction, and the desired products can be afforded in good to excellent yields regardless of the benzamides possessing electron-donating groups or electron-withdrawing groups; comparatively, substrates containing electron-donating groups result in slightly higher yields of the coupling products than those of electron-withdrawing groups. Moreover, a gram-scale bromination reaction was also successfully fulfilled, demonstrating its potential applicable value in organic synthesis.