The decarboxylative addition of N-Cbz-Pro to diethyl maleate (Figure ) was selected as a model reaction to investigate oxidative photocatalysis through a reductive quenching cycle; both [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 and 4CzIPN have been shown to be highly effective and both of them were described to be reductively quenched by the deprotonated form of N-Cbz-Pro. According to these literature reports, the PC must be capable of first oxidizing the N-Cbz-Pro carboxylate (Eox = 0.68 V vs SCE in DMF for tert-butylammonium N-Cbz-Pro salt, Figure ) as well as being suitably reducing in the ground state to reduce the in-situ generated α-acyl radical, as depicted in Scheme 1. The literature yield of 93% obtained using [Ir(dF(CF3)ppy)2(dtbbpy)]PF6 could be replicated in our setup (Table ), while with 4CzIPN as the PC, the yield obtained was higher than that reported by Zeitler et al. (99% vs 80%, respectively).