Studies On Enaminone Synthesis And Derivation

As a class of important onganic synthons,enaminones are widely used in the synthesis of pharmaceuticals,functional materials and various small organic molecules.Therefore,research work on the synthesis of enaminones and their derivatization is of high significance for exploring and making use of enaminones in broader scope.This research work in this thesis focuses on the synthesis as well as derivatization of enaminones,and consists of four different sections of research work.The first section,the synthesis of sulfur-bridged bis-enaminones via the vinyl C-H bond thiolation.Using N,N-disubstituted enaminones,aromatic amines and elemental sulfur,the three-component,one-pot synthesis of sulfur-bridged symmetrical bis-enaminones have been realized via iodine promotion.Identical conditions allow the formation of sulfur-bridged bis-chromones when o-hydroxylphenyl functionalized enaminones.The second section,visible-light-induced vinyl C-H thiocyanation of enaminones.Under the promotion of visible light,the ?-C-H thiocyanation reactions of N,N-disubstituted enaminones have been investigated.By using rose bengal as the photocatalyst,the green synthesis of ?-thiocyano enaminones has been realized at room temperature without using metal catalyst.When o-hydroxylphenyl enaminones are used as substrates,the reactions selectively give 3-thiocyanochromones.In addition,preliminary studies demonstrate that this method is also applicable for the selenocyanation of enaminones.The third section,synthesis of different N,N-disubstituted enaminones via transamination.Tradditional enaminone-based reactions involves mainly the application of N,N-dimethyl enaminones.In order to make enaminones more diversified,the synthesis of various N,N-disubstituted enaminones via the transamination between the N,N-dimethyl enaminones and secondary amines has been investigated by employing biomass-based ethyl lactate(EL)as medium.The fourth section,selective synthesis of disulfide functionalized enaminones and 1,4-thiazine.By making use of N,N-disubstituted enamiones and ?-thioethanamine as starting materials,the selective synthesis of disulfide functionalized enaminones and 1,4-thiazines are achieved.When performing the reaction in water and catalyst-free condition,the disulfide functionalized enaminones are produced.On the other hand,the employment of the CuI as catalyst in dimethyl sulfoxide enables the selective generation of 1,4-thiazines with identical substrates.