| Heterocyclic molecules play critical important roles in biomedical,pharmaceutical chemistry and material science.Therefore,it is of great significance to develop new methods to construct the heterocyclic skeleton motifs.It's known that the transition-metal-catalyzed isomerization reactions of 1,n-diynes can efficiently and selectively construct novel heterocyclic compounds.In this study,novel transition-metal-catalyzed cascade cycloisomerization reactions of 1,n-diynes with N-halosuccinimide were well studied,to selectively produce series of heterocyclic compounds.The main contents of this thesis are presented as below.In the first part,transition-metals-catalyzed intermolecular or intramolecular cycloisomerization reactions of 1,n-diynes,to generate various heterocycles were summarized.In addition,the mechanisms of some of the reactions were briefly described.In the second part,Pd-catalyzed cycloisomerization reactions of 1,6-diynes with N-bromosuccinimide(NBS)were reported,and a series of stereo-defined dibromo-substituted heterocyclic molecules or methylene cyclohexenes were produced in good yields.The structure of the product was confirmed by X-ray diffraction analysis.Mechanistically,the reaction occurred in two consecutive steps.NBS was found to be a suitable Br radical source to initiate the PdII-PdIII-PdI-PdII catalytic cycle.The products 2H-pyran were treated with HSi Et3 and B(C6F5)3 to induce their ring opening reaction,which resulting the stereo-defined dibrominated 1,3-dienes with regioselectivity.In the third part,we reported an Iron-catalyzed tandem cycloisomerization reaction of diynols with NBS,to produce indene skeletons with pharmacologically active in a one-pot protocol.Two different cis-or trans-isomers of indene compounds were found to generate in this reaction.However,the cis-structure would be transformed into trans-isomer through heating conditions.The structure of the cis-indene compound was confirmed through X-ray diffraction analysis. |
PDF Full Text Request