Visible-light-mediated photochemistry: accelerating Ru(bpy)₃²⁺-catalyzed reactions in continuous flow

The first application of visible-light-mediated synthetic photochemistry in continuous flow is described. Using an operationally simple photoreactor design, several Ru(bpy)₃²⁺-catalyzed transformations were performed with 10–50 fold rate enhancement over the corresponding batch methods. In the process, lower catalyst loadings were needed to produce the desired products in excellent yields within residence times between 1 and 30 min, while minimal waste byproducts were formed. The process is readily scalable and provides access to large quantities of product in relatively short time.