Studies On The Synthesis Of Alkyl Bisimidazole Salts And Cyclopalladated Ferrocenylimine Catalyzed C-H Arylation Reaction Of Heterocycle

In this paper, the synthesis of alkyl bisimidazole salts and cyclopalladated ferrocenylimine catalyzed C-H bond arylation reaction of heterocycles were studied. The main contents are just as follows:1) Studies on cyclopalladated ferrocenylimine catalyzed C-H bond arylation reaction of heterocyclesBenzoxazole are important moieties frequently present in natural products, organic dyes, pesticides, pharmaceutically active substance whose diverse biological activity is an important content of synthetic chemists. It was found that cyclopalladated ferrocenylimine (0.5%) was one kind of efficient catalytst for C-H arylation of benzoxazole and arylhalide when using CuI (10%) as co-catalyst, DMA as solvent, K2CO3as base at140℃under N2(Scheme1). Good to excellent yields were obtained when various aryl iodides were employed under optimal reaction conditions. Interestingly, good yields were still achieved when some aryl bromides with electron-withdrawing groups were used.2) Studies on the synthesis of symmetry alkyl bisimidazole saltsThe property, synthesis, species and developments of the ionic salts were review ed.Three kinds of symmetry alkyl bisimidazole salts were synthesized accoring to the literature (Schemes2-4). All the compounds were characterized by M.P,1H NMR,13C NMR, IR and MS. Compounds2c,4b,4c,5a,6a,8,8a,9a were new compounds and characterized by HRMS.1. The corresponding iodo-salt2b,4b were prepared via bis-N Alkylimidazolium2a、4a undergo anion exchange by the benzylation of Imidazole and dibromo alkane。1、3were reacted with bromoacetophenone can generate imidazolium salt substituted by phenacyl2c,4c (Scheme2). Wherein4b,2c,4c were unreported new compound.2. Alkyl imidazolium salts5a,6a,7a (Scheme3) were prepared via N-alkyl imidazole5,6,7by the benzylation of Benzimidazole and dibromoalkane and5a,6a were unreported as newcompound. 3. The diphenyl substituted imidazole was synthesized by benzoin condensation, FeCl3oxidation and cyclization with Benzaldehyde as a raw material. The bis imidazol-bromide salt8a,9a (Scheme4) was obtained by benzylation of bis-N Alkyl(4,5-diphenyl)imidazolium8,9which prepared by the reaction between Diphenyl substituted imidazole and different chain length of the alkyl bromide.