Studies On The Synthesis Of Pyrrole And Dihydropyrrole Compounds Based On Chalcones

Pyrrole/dihydropyrrole and its derivatives are a class of important pentatomic heterocyclic compounds,which existed in a wide range of drugs,pesticides,dyes and photoelectric materials et al.Because of the highly biological activities these molecules present and thus have been widely used as antitumor,antibacterial,antioxidant etc.Give the importance of ploysubstituted pyrrole derivatives,the synthesis of ploysubstituted pyrroles has been the hotspot and difficulty of organic chemistry.Chalcone derivatives have been found in many natural products which have shown many interesting features regarding pharmacological and physiological activities as well as widely applied in organic synthesis.In this context,the research topic is: Studies on the synthesis of pyrrole and dihydropyrrole compounds based on chalcones.The thesis involves following three aspects:1.KI/Cu(AcO)2–catalyzed tandem Miachael/cyclization sequence was developed for the synthesis of a series of 23 polysubstituted pyrroles from chalcones and ?-enamines.We have developed a novel method for the construction of new pyrroles,and have surveyed the reaction conditions,such as various of solvents,temperature,ratio of substrates,additives and so on.The results showed that the optimal parameters were as follows: a mixture of chalcones,1.2 equivalent ?-enamines,0.2 equivalent KI,2.0 equivalent Cu(Ac O)2 and 1 equivalent K2CO3 together with 2 mL DMSO under 120 ? and obtained corresponding products in 31-92% yields.All of these products were new compounds.2.A tandem Miachael/cyclization/elimination sequence was studied for the formation of a series of 24 polysubstituted 2,3-dihydropyrroles from chalcones and ?-enamines.The results showed that the optimal parameters were as follows: a mixture of chalcones,1.2 equivalent ?-enamines,1.5 equivalent ZnI2,1.5 equivalent FeCl3 and 1 equivalent K2CO3 together with 2 mL DCE under 80 ? and obtained corresponding products in 20-60% yields.3.The novel Cu(Ac O)2–catalyzed 1,3-dipolar cycloaddition/oxidation /aromatization cascade process with DDQ as the terminal oxidant for the construction of pyrrolo[2,1-a]isoquinolines was reported.The reaction was discussed and the parameters were selected.The results showed that the optimal parameters were as follows: 1.0 equivalent Cu(AcO)2,1.0 equivalents DDQ,DMSO as solvent,a series of 27 products were obtained in 30%-94% yields under 120 ? from the reaction between chalcones and tetrahydroisoquinoline.26 of these products were new compounds.Comparing with reported methods,this novel method was simple and economic.