Photoreduction of 9,10-phenanthrenequinone (PQ) in the presence of p-substituted N,N-dimethylanilines and polymethylbenzenes affords corresponding phenolethers as primary products. In the subsequent process shielded from light, phenolethers, which were formed by photoreaction of PQ with N,N-dimethylanilines, were quantitatively converted to give corresponding ketols. Phenolethers of 9,10-phenanthrenequinone