The combination of a Ce(IV) salt and benzoate derivatives is essential for product formation. Notably, the yield could be enhanced by in-situ deprotonation of benzoic acid using Cs2CO3 (Table , entry i) instead of tetrabutylammonium benzoate (Table , entry a). Interestingly, the photo-transformation necessitates high light intensity rather than high light energy, as evidenced by the fact that LEDs emitting at 385 or 455 nm (~200-300 mW) with medium light intensity failed to induce the photon-induced bond homolysis of the cerium-oxygen bond in the respective benzoate complex (entries g and h). Similar observations were reported by Zuo's group, who utilised high-intensity LEDs in their cerium photocatalysis reactions. A maximum yield of 86% was obtained using 2 mol% of CeF4 and benzoic acid, respectively as well as 5 mol% of Cs2CO3, along with a starting material ratio of 1:1.5 for ester 1 (0.1 mmol) and phthalimide 2 (0.15 mmol) in 1 mL of dry acetonitrile under irradiation with a 395 nm LED (~2.6 W) for 24 h at 25 °C (Table , entry j). Subsequent experiments were performed with 5 mol% of the cerium salt, ligand, and caesium carbonate, respectively, for better preparative handling (Supporting Information Table for detailed information).