Synthesis And Transformation Of Functionalized 1,4-dicarbonyl Compounds

1,4-Dicarbonyl compounds as important organic chemicals,are not only common substructures of natural products and biologically active molecules,but also significant chemical raw materials and organic synthetic intermediates.Therefore,exploring a strategy that is simple,eco-friendly and cost-effective to synthesize 1,4-dicarbonyl compounds is of significance for the development of organic synthetic chemistry,exploitation of medicine and natural products.Although the reactivity of 1,4-dicarbonyl compounds is relatively rich and mostly predictable,the structural diversity and the presence of multiple reaction sites make 1,4-dicarbonyl compounds often show unexpected reactivity when applied in synthesis.Hence,developing a novel transformation path to 1,4-dicarbonyl compounds and their derivatives has high academic value in promoting the research and development of organic synthetic chemistry.Based on the above,this thesis focuses on developing a novel,efficient and green method to synthesize 1,4-dicarbonyl compounds and further making a detailed research on their transformation.The primary contents are composed of the following three parts.(1)According to the tandem reaction of aldol dehydration and Michael addition reaction,1,4-diketones were synthesized.1,4-diketones containing indoles functional groups were synthesized efficiently from methylglyoxal,acetylacetone and indol in water and without the addition of catalyst.Besides indol and its derivatives,thiophenol,mercaptan,1-methylpyrrole,2-methylfuran,N,N-dimethylaniline and so on were used as nucleophiles in the reaction system.The synthesized polysubstituted 1,4-diketones could also be converted into a variety of valuable small molecular compounds and some of them were difficult to be prepared by other methods,thus providing a novel synthesis block for organic synthesis.(2)Carbazoles were synthesized from indol-substituted masked 1,4-dicarbonyl compounds containing an acetal fragment and 1,3-dicarbonyl compounds.The raw materials of indol-substituted masked 1,4-dicarbonyl compounds were synthesized via three-component reaction of glyoxal dimethyl acetal,acetylacetone and indol.Then the obtained raw materials reacted with 1,3-dicarbonyl compounds in nitromethane with the acid catalyst of scandium trifluoromethanesulfonate to form the products of carbazoles.This method characterized by its simplicity,easy availability of raw materials and mild conditions was demonstrated to be convenient for preparing carbazoles that were difficult to obtain through other traditional methods and thereby enriched the variety of carbazoles.(3)Pyrroles were synthesized by the reaction of masked 1,4-dicarbonyl compounds containing an amino group and an acetal fragment group and 1,3-dicarbonyl compounds.The raw materials of masked 1,4-dicarbonyl compounds were prepared through Mannich reaction of glyoxal dimethyl acetal,arylamine and acetone.Then pyrroles containing carbanyl group were synthesized from masked 1,4-dicarbonyl compounds and 1,3-dicarbonyl compounds in acetonitrile with scandium trifluoromethanesulfonate as catalyst.This method provided a fast and efficient approach to obtain multi-substituted pyrroles containing specific functional groups in a common catalytic system.The raw materials were easy to obtain and the derivatives of pyrrole were difficult to be prepared by other methods,therefore opening up new paths to synthesize pyrroles.What's more,the synthesized pyrrole could be converted to some important heterocyclic compounds such as indoles,2-formyl-N-arrylpyrroles and hydroquinone derivatives.