Studies On The Au(I)/I~-promoted Cyclization Of Enynones To Furans And Their Biological Activity

Furan,served as a valuable structural skeleton,exists in many natural products,bioactive compounds and functional materials.Therefore,the new strategies for synthesizing furans via a concise and efficient way are highly desirable.Here,we reported NIS and Au(I)-promoted the cyclization of ynenones respectively to construct three kinds of furan derivatives with high-selectively via a key furanium ion intermediate 1-73.The 1-site of intermediate 1-73 with electrophilicity can be attacked by nucleophiles.The hydrogen at 2-site of intermediate 1-73 has acidic,because of the molecular polarity of furanium ions,which can react with base.Summarized as follows:(1)NIS was used in the cyclization of ynenones firstly to construct 16 kinds of Z-iodovinylfurans with high efficience and selectivity.The iodine cation promoted the cyclization to give iodine-substited intermediate 1-73 via electrophilic cyclization reaction,followed by the succinimide anion generated from NIS catched the hydrogen on the 2-site of intermediate 1-73 to give furans.The solvent DMSO,a nucleophilie,attacked the 1-site of intermediate 1-73 to form 25 kinds of 2-acylfurans.(2)7 kinds of sterically hindered and bifunctional phosphine ligands were synthesized.The gold catalysts with suitable bifunctional phosphine ligands were used to catalyze ynenones to 10 kinds of E-alkenylfurans.The proposed mechanism was that the amine group of the ligand served as a Lewis base to catch the hydrogen on 2-site of 1-73,prompting the carbon anion of 2-site to feedback electrons to give furans.Through the reaction of Au(I)or I~+promoted the cyclization of enynones to construct furan derivatives efficiently and high-selectively,the following conclusions are obtained:(1)1-site of intermediate 1-73 with electrophilicity can be attacked by nucleophiles;The hydrogen on 2-site of 1-73 with acidic can reacts with base to form carbanions.(2)Au(I)or I~+promoted the cyclization of enynone to construct 51 furan derivatives in3 types via the furanium ion intermediate 1-73.(3)Both metallic Au(I)and non-metallic I~+are soft electrophiles,with some similarities in activating alkynyl.Three different types of furan derivatives were used for the activity test of E.coli and Salmonella with inhibitory concentrations>50?g/ml and inhibitory ratio<20%.The results show that the antibacterial activity needs to be further excavated.