An efficient free radical ester synthesis through a visible light-induced hydrogen atom transfer process

Phenanthraquinone (PQ) can absorb both ultraviolet (UV) and visible light, despite the reported UV induced hydrogen atom transfer (HAT) process, the potential of PQ for visible light-excited photosynthesis is underexplored. Here a new efficient free radical photochemical addition of aldehydes to PQ at room temperature is described. we demonstrate that PQ can convert aldehydes to its radical through a visible light-induced HAT process. In these reactions, monoesters of 9,10-dihydroxyphenanthrene could be obtained in high yields.