Finally, we demonstrate the scalability of our photochemical C1 homologation using flow technology (Figure ). In batch settings above 1 mmol, the heterogeneous reaction mixture led to a significant drop in yield of the desired product 3 (see Supplementary Information, Section 9.1). Suspecting nonuniform irradiation and limited light penetration at larger scales, we transitioned the photochemical alkylative step to continuous flow. After an extensive optimization conducted at 0.2 mmol scale (see Supplementary Information, Section 9.2), we established conditions for the protocol using a