Functionalization Of Internal Olefinic C-H Bonds By Visible Light Photoredox Catalysis

Visible light photoredox reaction is a new type of organic synthesis, chemists have paid more and more attention to it in recent years. After the discovery of visible light photoredox catalysts, chemists have realized the organic synthesis induced by visible light, which promoted the rapid development of the visible light photoredox chemistry, such as: trifluoromethylation of olefins( or romatic rings), reducing dehalogenation of halogenated compounds, ring-opening reaction of the epoxide,( or acridine), oxidative reaction aldehydes and reductive reaction of ketones. This dissertation explored the bromination reactions and trifluoromethylations of the α-oxoketene dithioacetals induced by visible light.In This dissertation selected the phenyl-α-oxoketene dithioacetals as the template, and 5W blue LED light as light source. Meanwhile, the optimal reaction conditions were identified after screening. The trifluoromethylation at the α-position of the carbonyl group was realized with Togni’reagent as oxidant and trifluoromethyl agent, DMSO as solvent, Na2CO3 as alkali, Ru(bpy) 32+ as a catalyst, which synthesized a series of trifluoromethyl derivatives of α-oxoketene dithioacetal; Similarly, brominated products at the α- position of the carbonyl groups were achieved after the replacement of Togni’reagent with CBr4 as an Oxidant. In this dissertation, 19 α-oxoketene dithioacetal derivatives were prepared, and based on these results, the plausible reaction mechanism was proposed as follows. In the recation, the radicals of CF3 is added to the C=C of α-oxoketene dithioacetals with providing trifluoromethylated α-oxoketene dithioacetals. And the bromo α-oxoketene dithioacetals were abtained through an additon of carbon-carbon double bonds of the substrates with Br2, which was generated in situ with visible light photoredox catysis.Comparing with the traditional synthesis methods of trifluoromethylated α-oxoketene dithioacetals and bromo α-oxoketene dithioacetals, the synthesis in this dissertation has such advantages: environmental friendliness, mild conditions, and high yields.