The synthesis of aromatic EPOs has been optimized adapting a previously published procedure to a photochemical reactor equipped for continuous flow irradiation (Vapourtec® E-Series, see SI for detailed description of the instrument and the synthetic procedure). The interest of the synthetic organic community towards flow processes is rapidly growing for an increasing number of applied chemical processes. In particular, photo-induced and catalyzed transformations capitalized on the use of this technology to improve reaction rate, yield and batch size, especially thanks to the massive surface-to-volume ratio enabling increased efficiency and homogeneity of irradiation.[30] For our purpose, the reactor was endowed with a LED lamp emitting at 525 nm (± 10 nm) and it enabled fine control of the light intensity, the inner reactor temperature and the flow rate, which could be adjusted according to the desired residence time.