Cinnamate Ammonia Bromination Of Its Applied Research, The Structural Transformation Of The Natural Product

The aminohalogenation(or haloamidation) is a reaction for the converting common petroleum olefins into vicinal haloamine products by the addition of amine and halogen moieties onto carbon-carbon double bonds.Under certain conditions,the adductive products of haloamidation could be converted into useful molecular through a nucleophilic substituentional reaction of intermolecular and intramolecular.This reaction is general high Regio-and Stereoselective.Thus,it has become an interesting topic in modern organic synthesis,building blocks of heterocycle compounds as well as pharmaceutical molecular synthesis for 40 years.Due to the important application in organic synthesis and pharmaceutical chemistry,the synthesis and nature research of haloamino product become an active research field in the world.Meanwhile, the confusing mechanism hypothesis of the original aminohalogenation may also have attributed to this situation.So researchers are interested in the topics as follow so far:1.The research for screening various nitrogen/halogen sources.2.The research for explore new catalysts.3.The research for expanding substrate scopes.4.Asymmetric synthesis of aminohalogenation.The catalysts are currently believed to play a key role in the aminohalogenation ofα,β-unsaturated esters and many efficient catalysts have been reported in the literature in the past two decades.However,these catalysts still appeared to have several shortcomings,such as high molecular weight,hygroscopicity,high cost,and high catalyst loadings.Therefore,the work of choice and the study of the haloamino catalyst attract more and more attention in the Chemical field.Adductive products of aminohalogenation forα,β-unsaturated esters can easily hydrolyzed toαorβ-amino acids.So it can be used to synthesizeαorβ-amino acids.Cinnamic esters are believed to be one of the most useful substrate classes.Basd on this situation,in this paper,we have developed a new system for the aminohalogenation of cinnamic esters.Using this method, we have synthesized 19 samples of haloamino products of cinnamic esters catalyzed by Al powder with NBS,p-toluenesulfonamide as bromine source and nitrogen source at room temperature without inert gases protection.Affacting factor for the aminohalogenation of cinnamic esters have been investgated.Experiment results indicated that the chemical yield,regio-and stereoselective, and their reaction active of cinnamic esters strongly depended on the electronic density on the double bond of substrates.Using this method,the diosgenin structural reformation work has been mad successfully.The first chapter is a summary on research progress of the aminohalogenation and various catalysts' catalytic effect onα,β-unsaturated double-bonds and selective of halogen and nitrogen sources.In the chapterâ…¡,the method of various cinnamic esters of haloamino addition reaction have been developed,in which Al powder is as catalyst,NBS is as bromine source, p-toluenesulfonamide is as nitrogen source.The reaction active of the substrates was investgated through experiments and the products structure were characterized by elemental analysis,¹H NMR and ¹³C NMR.These esters in which the OCH₃ bearing at the 4-position of benzene ring can afford a better yield with catalyst Al powder.We also focus on that the different reaction yields depended on the different functional groups on the cinnamic esters.For example,the reaction was completed in 1.5 h with good yield of 96.5%when p-methoxy ethyl cinnamate reacted with NBS and p-methyl benzsulfonamide under catalyst Al powder.However,the yield was only 20.5% when the benzene ring with electron withdrawing group in cinnamic ester's double bond,such as 4-bromo ethyl cinnamate react with NBS and p-methylbenzsulfonamide under catalyst Al powder in 24 h.In this paper,Al powder as catalyst,the aminohalogenation reaction of cinnamic ester is easy to carried out under room temperature.The operation is simple and it reacts under mild reaction conditions with good yield.In the chapterâ…¢,Using this method,the diosgenin structural reformation work has been mad successfully.The products were characterized by elemental analysis,IR,¹H NMR and ¹³C NMR.