Arylated and α,α'-diarylated carbonyls are an important class of building blocks and widely found in biologically active natural and unnatural molecules. The most popular approach to access α-arylated and α,α′-diarylated carbonyls involves transition-metal-catalyzed cross-coupling reactions and metal-free coupling reactions, which always request harsh conditions or high catalytic loading. Visible-light photoredox catalysis, a novel and green catalytic strategy, has recently received increasing attention from chemists and been widely applied to organic synthesis in the past years. Inspired by the recent process of the visible light photocatalytic generation and exploration of α-keto acids as the precursor for acyl radical in decarboxylative coupling reactions and 1,4-Michael addition reactions, we found that, however, expand their utilization in more complex systems, such as 1,6-conjugate addition with electron deficient olefins, remains underdeveloped, particularly due to the difficult to design the appropriate substrate, and the harsh conditions often required for metal-catalyzed redox neutral decarboxylation. Here, we report a photoredox catalytic CC bond formation reaction that enabled by visible-light. The versatility of this protocol has been portrayed by using a wide range of stable and easily accessible aromatic α-keto acids as well as p-QMs. This synthetic strategy also offers access to 24 kinds of different α-keto-α,α'-diarylated ketones in moderate to excellent yields under mild conditions. A representative procedure for the reaction is as follows: 2-oxo-2-phenylacetic acid 1a (0.10 mmol), the p-QM (2,6-di-tert-butyl-4-(4-methoxybenzylidene)cyclohexa-2,5-dien-1-one) 2a (0.12 mmol), photocatalyst Ir[dF(CF 3)PPy] 2 (dtbbpy)PF 6 (0.001 mmol) and K 2 HPO 4 (0.12 mmol) were dissolved in DCM (1 mL). Then, the resulting mixture was degassed and refilled with N 2 via 'freeze-pump-thaw' procedure (3 times). After that, the solution was stirred at a distance of ca. 5 cm from a 36 W blue LEDs at room temperature for about 12 h with TLC monitoring. Upon completion of the reaction, the crude product was purified by flash chromatography on silica gel (hexane/ethyl acetate) to give the desired product 3.
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