Investigation On Several Solvent-Free Addition Reactions And Aminohalogenation Reaction Of Olefins

Large numbers of chemical products were required in the rapid developing modern society which can cause many serious environmental problems in the producing process.To perform the chemical synthesis in an environmentally friendly way is one of the most urgent tasks assigned to our chemists.In this situation,some safer and more convenient synthetic methods have been developed,replacing the traditional organic solvents and precious and toxic metal catalysts with environmentally safe ones.Performing organic reactions under solvent-free mechanical milling conditions,utilizing water as reaction medium,as well as the small organic molecular-catalyzed reactions are among the most concerning topics.In this thesis,investigations are focused on the mechanochemical solvent-free addition reactions and aminohalogenation reactions of olefins.1.gern-Dichloroaziridines were synthesized in a ball mill under solvent-free conditions.Their hydrolysis promoted by Lewis acid was also investigated under the same conditions.The aniline and aromatic aldehyde were mixed in a reaction vessel,and the thus formed imine could react directly with dichlorocarbene generated from chloroform in the presence of KF/Al₂O₃.With the promotion of Lewis acid,these aziridines were readily hydrolyzed to generateα-chloro-phenyl-acetamide.This solvent-free reaction required only a small quantity of carbene source to give the final product in high yield.2.The Friedel-Crafts type alkylation reaction of indole with epoxy ketones were carried out successfully under ball-milling conditions in the presence of Lewis acid as catalyst.Further investigation indicated that InCl₃·4H₂O afforded the highest yield.The advantage of this methodology is solventless reaction condition, short reaction time,mild reaction process and simple manipulation.3.The aminochlorination reaction of electron-deficient olefins promoted by hypervalent iodine compound was realized under solvent-free mechanochemical conditions.Compared with the previous methods,this process could be performed in moisture without any solvent and metal catalyst,affording the products in good yields and high regio- and diastereoselectivities with shorter reaction time.The strong oxidant PhI(OAc)₂ was used to promote this reaction for the first time,and substoichiometric loading(50 mol%) was enough to give a high-yielding reaction.Under the same condition,various metal chlorides could also promote this aminochlorination reaction to some extent,among which InCl₃·4H₂O gave the best result.When the reaction was performed in organic solvents,none or only low-yielding product was obtained,which demonstrated the superiority of our ball-milling method.4.The PhI(OAc)₂-promoted aminobromination reaction of electron-deficient olefins with sulfonamide as nitrogen source and NBS as bromine source under mechanical milling conditions was demonstrated.In this reaction, substoichiometric PhI(OAc)₂ was used and the products were obtained in good yields and high regio- and diastereoselectivities.5.An efficient and practical procedure for the aminohalogenation of electron-deficient olefins promoted by hypervalent iodine compounds has been demonstrated.The catalytic efficiency of various hypervalent iodine compounds with different carboxylic and sulfonic ligands has also been investigated and (diacetoxyiodo)benzene exhibited the highest activity.The aminobromination reaction could be performed on multi-gram scale which exhibited the advantage of this reaction.Furthermore,the influence of various nitrogen and bromine sources was investigated and the possible mechanism of this reaction was discussed.6.The aminochlorination of electron-deficient olefins was realized in water for the first time promoted by Bronsted acids.Previously,these reactions were performed in dry acetonitrile which was manipulatively complex and environmentally unfriendly.In this study,we found that the electron-deficient olefins could be easily aminochlorinated with high yield and selectivity in acidic water with Chloramine-T as chlorine and nitrogen source.This reaction could only be performed in water;when organic solvent was used,the reaction failed. Furthermore,the reaction could proceed successfully on multi-gram scale,which exhibited the possible application in industry.7.With TsNH₂ and NBS as nitrogen and bromine sources respectively,the aminobromination reaction of electron-deficient olefms could be catalyzed by 20 mol%of(diacetoxyiodo)benzene,and the reaction could only proceed in pure water.This reaction was performed with high efficiency and stereoselectivity. Furthermore,the double bond of styrene was also tolerable under the present condition,which demonstrated that(diacetoxyiodo)benzene was a powerful catalyst in this kind of reaction.