Study On Visible-Light-Induced Acylation Coupling Of Heterocycles

As important organic compounds and key synthons of complex frameworks,aldehydes and ketones can undergo various chemical transformations,which provides them with wide applications in drug synthesis,fine chemicals and natural products.Building C-C and C-heteroatom bonds through the activation and functionalization of C-H bonds in organic molecules provides a new synthetic strategy for organic synthesis.Acylated derivatives of heteroarenes have unique physical properties and biological activities,as well as potential application value in commercial drugs and biochemical engineering.In this dissertation,two heteroaromatic acylation coupling reactions under visible light induction have been studied to prepare a series of acylated derivatives of heteroarenes.Compared with traditional methods,this work uses inexpensive carboxylic acids as starting materials,and has the advantages of simple operation,mild conditions,and environmental friendliness,and conforms to the principle of atomic economy and the concept of green chemical industry.Using a variety of heteroaromatics as substrates and 2,2-diethoxyacetic acid as the carboxylic acid source,the formylation of heteroaromatic compounds was investigated under optimized reaction conditions.The synthetic strategy has a good substrate scope,and a series of hydroformylated heteroaromatics have been prepared(20-80% yield).Control experiments showed that the reaction took place via a free radical pathway.Under the irradiation of visible light,2,2-diethoxyacetic acid was decarboxylated under the effect of persulfate to give free radicals,which added to heteroaromatics.With further oxidation of persulfate,heteroaryl acetals were obtained.After acid-catalyzed hydrolysis,the corresponding hydroformylated heteroaromatics were obtained.Based on the work above,visible-light-induced decarboxylative coupling of α-keto acids and heteroaromatics were studied to construct acylated heteroaromatic products under optimized conditions.The method has good functional group applicability and can prepare various types of heteroaromatic acylated derivatives(30-84% yield).Control experiments showed that the reaction proceeded through a free radical pathway,under the induction of visible light,α-keto acids were decarboxylated to couple with heteroaromatics and gave acylated heteroaromatics.