We also examined if Cs2CO3 could be replaced by other bases to improve the yield of 5a. As shown in Table , LiOH was found to be the most suitable among the inorganic bases that were screened (entries 3-7). Further optimisation revealed that product 5a was formed in 60% yield using a combination of 0.5 equiv. of LiOH and 20 mol% of Cu(CF3COO)2 (Table , entry 13). Finally, several control experiments were performed to address the role of the bases, the metal catalysts, and the presence/absence or nature of irradiation. Only trace amounts of 3a and 5a were obtained in the absence of light, a base, or Cu(CF3COO)2 (Table , entries 8 and 14-16) which clearly indicated that a photoredox catalytic system was essential for the transformation. Notably, the reaction was observed to be critically dependent on the presence of molecular oxygen. For instance, when the reactions were conducted in a nitrogen atmosphere, no product was formed, and the substrate