Visible-Light Enhanced Base-Promoted Dehalogenations And Carbonylative Cyclizations Involving Aryl Radicals

Our research groups have been working on the base-promoted radical reaction and the detailed exploration of its mechanism.In view of the base-promoted intramolecular tandem cyclization reaction,we envisige whether clean and renewable visible light could be used to induce the base to generate aryl radicals.Based on these assumptions,we have developed a radical reaction promoted by the base and the visible light.In this regard we have achieved the following research results.These research results fully illustrate the feasibility of the reaction mechanism.The use of mild reaction conditions and cheaper and more readily available chemical reagents for chemical conversion have important application value.(1)The dehalogenation reactions of aryl halides promoted by the base and the visible light have been developed,and the dehalogenation reactions of aryl halides without transition metal catalyst or dye catalyst under the condition of the visible light have been realized.Through a series of experiments of isotope labeling experiments and control experiments,the existence of phenyl radical was proved.And a reasonable explanation was provided for the reaction mechanism.It was found that no additional hydrogen source was needed in the system,and the solvent provided the hydrogen source of the halogenation reaction.(2)We found intramolecular tandem cyclization to construct the[6+6+5+6]tetracylic acene and developed a carbonylation reaction of aryl amidates to synthesize phenanthridinones.For this special framework,we used this method to synthesize inhibitors of Mycobacterium tuberculosis H37Rv and precursors of optoelectronic materials.The reaction mechanism is a free radical reaction promoted by the cooperation of the base and the visible light.(3)Based on the specificity of the structure of 2,3-dicarbonylpyrrole,we have found that under the conditions of Wittig reaction,2,3-dicarbonylpyrrole can directly realize the dienylation cyclization of carbonyl group to synthesize highly functional indole.Under the conditions of Julia reaction,2,3-dicarbonylpyrrole can only promote the cyclization of the monoalkenyl product to obtain a polysubstituted indo lino line.We also briefly explained the mechanism of the reaction.