Metal-free/Iron-catalyzed Construction Of Acetylimidazoles And Six-membered N-containing Heterocyclic Compounds

Nitrogen heterocyclic compounds are irreplaceable in agriculture,biology,materials and medicine,and are constantly attracting researchers to develop more accesses to obtain nitrogen-containing compounds.In the efficient,simple,environmentally friendly and economical principle,we proposed new proposals to synthesize poly-substituted imidazoles and poly-substituted pyrimidines.Also,we studied the mechanisms via a series of control experiments,respectively.And some compounds were confirmed by X-ray diffraction analysis.1.The introduce of imidazoles and the description of the synthesis of imidazole compounds,and the development of ?,?-unsaturated aldehydes/ketones involved in the ring addition,hydrocarbon activation,oxidation and reduction reactions were referred.We reported an FeCl3 ? 6H2 O and molecular iodine catalyzed [3+2]cycloaddition reaction to obtain 1,2,4,5-substituted imidazoles from ?,?-unsaturated aldehydes/ketones and amidines.In this reaction,ferric salt were used as the catalysis and lewis acid.Products were obtained in good to excellent yields with 100%regioselectivity.We contributed to simple,environmentally friendly and efficient results,which were satisfactory to us.Yields of 55 substrates reached to 43-97%.2.N-toluenesulfonyl hydrazones were usually acquired by direct reaction of simple aldehydes or ketones and hydrazides,and the activity of the compounds were relatively high.In some cases,they could be as a diazo compound to participate in the reaction by removing the sulfonyl group.On the other hand,they could proceed hydrocarbon activation and coupling reaction with the sulfonyl hydrazide group as a leaving group.Since N-toluenesulfonyl hydrazones could be formed to carbenes under certain conditions,we succeeded to construct C-N bonds with N-toluenesulfonyl hydrazones and arylamidines.We obtained a lot of 1,2,4-trisubstituted imidazoles in the presence of 1 equivalent molecular iodine and 2 equivalent t-BuOLi in toluene under 70 oC.We studied the mechanism via a series of control experiments.Thereaction contributed to aryl-and alkyl-substituted imidazole derivatives with no need of transition-metal-catalysis or ligand.3.A review of some reactions with nitrogen oximes as good nitrogen sources and some methods to construct pyrimidines were introduced.We proposed a report to synthesize 2,4,5-trisubstituted carbonylated imidazoles and di/tri-substituted pyrimidines from available ?,?-unsaturated aldehydes/ketones and N-hydroxyamides,by controlling the addition of different promoters and alkalis,in which ferric salts were utilized as the catalyses.Mechanisms were explored.Reactions exhibited excellent selectivity and profitability,and were economical,efficient and environmentally friendly.Importantly,by controlling the use catalysts and bases,the reaction could proceed [3+2] and [3+3] cyclization reactions from the same substrates,respectively.This could provide a good reference to synthesize more ring addition products.