Chemoselective Cleavage and Transamidation of Tertiary p‑Methoxybenzyl Amides under Metal-Free Photoredox Catalysis

A metal-free and mild cleavage of tertiary p-methoxybenzyl amides (PMB tert-amide) under photoredox conditions is developed using Mes-Acr-Ph+BF4 – and Selectfluor to activate the electron-rich benzylic C–H bond of the PMB moiety. The resulting acyl fluoride intermediate is versatile and facilitates a one-pot transamidation of the PMB tert-amide. The value of this protocol is highlighted by performing the chemoselective activation of the PMB tert-amide in bifunctional molecules containing more reactive functionalities than the amide.