Visible-light-induced Construction Of 1,2-Dicarbonyl Indolizines And Its Photoluminescence

Indolizine is an important and unique nitrogen-containing heterocyclic compound commonly found in nature.The development of diversified indolizine compounds is of great value for the discovery of drugs and the application of fluorescent molecules.1,2-Dicarbonyl derivatives are key structural unit and intermediates in production of fine chemicals,and generally,these are synthesized by the oxidation of1,2-diols,alkyne,and alkene.With the increasing awareness of environmental protection and great progress in green and sustainable chemistry,the use of a renewable energy source for developing efficient and selective chemical transformations gained widespread attention.In the past few years,visible light as a clean,safe,pollution-free,cheap,abundant,sustainable energy,visible light catalytic conversion has been considered as an attractive synthetic strategy to activate C-H bonds.Starting from simple and easily available raw materials,we designed a mild,direct and environmentally friendly method to construct novel indolizine derivatives.We carried out the following work:(1)Visible-light-induced synthesis of dicarbonyl indolizine was designed.Through a series of conditions explore such as the selection of photosensitizers,the selection of solvent and the regulation of temperature and so on,visible-light-induced regioselective dicarbonylation of indolizines with oxoaldehydes via direct C-H functionalization was realized.Dicarbonylation of indolizine derivatives were synthesized with high yield and high selectivity.The method has good functional group tolerance,mild reaction conditions and excellent atomic economy.(2)Synthesis of a series of 1,2-dicarbonyl indolizine derivatives by the proposed synthesis method.Aiming at indolizines have high fluorescence quantum yield in the ultraviolet-visible region and as strong donating building blocks have great attraction in dye-sensitized solar cells,we explored the effect of dicarbonyl structure on the parent ring of indolizine.The solvent effects of some indolizine compounds in different solvents and the effects of different substituents on their ultraviolet absorption intensity and fluorescence spectra were investigated.