•Development of a photocatalyzed C–C bond scission of ketones•Ligand-to-metal charge transfer catalysis•Cooperative utilization of cerium and titanium catalysts In the endeavor to search for innovative catalysis, the synthetic chemists face ever-increasing financial and environmental demands in chemical production. The development of catalytic modes employing abundant and inexpensive metal catalysts has drawn significant research attention in the chemical community with regard to addressing the current challenges in the sustainable development of chemical synthesis. The selective C–C bond cleavage and functionalizations have recently emerged as an unconventional yet advantageous synthetic strategy, nevertheless, currently predominated by transition metals such as Rh, Ir, etc. The utilization of cost-effective and abundant metal catalysts would undoubtedly expedite the synthetic application of C–C bond cleavage transformations while addressing economic and ecological concerns; more importantly, the use of metal catalysts would potentially prompt the development of new catalytic paradigms. Here, we report a general catalytic manifold for the selective C–C bond scission of ketones via the exploitation of the ligand-to-metal charge transfer (LMCT) excitation mode. Through a cooperative utilization of Lewis acid catalysis and LMCT catalysis, the C–C bond of ketones could be selectively and effectively cleaved, enabling the installation of different functionalities at each carbon of the cleaved C–C bond through a sequential and orthogonal manner. This reaction manifold serves as a photocatalytic alternative to the Norrish type I reaction with the combination of visible light and inexpensive cerium salts. Under operationally simple conditions, a wide range of acyclic and cyclic ketones, from simple strained cyclobutanones to complex androsterone with less strained cyclopentanone moiety, could be successfully transformed into versatile chemical building blocks. Here, we report a general catalytic manifold for the selective C–C bond scission of ketones via the exploitation of the ligand-to-metal charge transfer (LMCT) excitation mode. Through a cooperative utilization of Lewis acid catalysis and LMCT catalysis, the C–C bond of ketones could be selectively and effectively cleaved, enabling the installation of different functionalities at each carbon of the cleaved C–C bond through a sequential and orthogonal manner. 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A careful examination of the reaction mixture indicated no sign of the corresponding cyanohydrin; however, it indicated a complete conversion of cyclobutanone to the cyanohydrin silyl ether, a protected form that cannot coordinate to cerium center to engage in LMCT catalysis (vide infra). Apparently, a Lewis acid that could deliver cyanohydrin in situ is essential, and several commonly utilized Lewis acids such as AlEtCl2 and ZnCl2 were found capable of facilitating the desired C–C bond scission, but relatively less effective than titanium tetrachloride. Building on the previous success of employing an additional photocatalyst to promote the turnover of the cerium catalytic cycle via PET, DPA was identified as the optimal PET catalyst among several photocatalysts. Although perylene diimide and Ir(ppy)3 photocatalysts demonstrated comparable efficiency, DPA was chosen as a more affordable co-catalyst. Furthermore, control studies revealed that cerium catalyst (entry 10) and light (entry 11) are all essential to the desired reactivity. Notably, the cleaved product 1 could be easily converted to the desired δ-valerolactam in high efficiency via a simple hydrogenation (see Supplemental Information). With the optimal conditions in hand, we next turned our attention to explore the scope of cyclic ketones in this cooperative catalytic system. As shown in Figure 3, this formal ring expansion protocol was applied to a range of cyclic ketones under mild conditions. Lewis basic functionalities, such as esters, Weinreb amide, sulfamide, and sulfone were well tolerated in this photocatalytic protocol. A series of strained cyclobutanones could be effectively cleaved and subsequently cyclized to produce the corresponding δ-lactams with moderate to excellent efficiency. 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