Studies On Iodine-Promoted Reaction For Construction Of C-N Bond Based On Chalcone

Nitrogen-containing organic compounds,due to their good biological activities,medicinal and practical values,are widely existed in medicines,pesticides,dyes,functional materials and other compounds,and are of great importance in organic chemistry.Therefore,the construction of nitrogenous compounds by C-N bond coupling has been the focus of organic synthetic chemists in recent years.In recent years,C-N bond coupling reactions catalyzed by transition metal has been widely reported.In this context,the main research topic was:Iodine-promoted reaction for construction of C-N bond based on chalcone.In this paper,a total of 86 target compounds of four series including multisubstituted tetrahydropyrrole derivatives,α,β-diaminone compounds and polysubstitutedα-enaminone compounds have been constructed by iodine-promoted C-N bond coupling reaction based on chalcone as the substrate,76 of these compounds have not been reported previously.The main research contents are as follows:1.Multisubstituted tetrahydropyrrole derivatives were synthesized from chalcone,amino acid ester and aromatic aldehyde upon the catalysis of iodine/potassium carbonate system in a one-pot process.Investigated the type of the catalytic system,base,the amount of base,the type of solvent,the amount of iodine,the ratio of material conditions and the optimum reaction conditions were obtained by using 0.8equivalent of molecular iodine,1.5 mmol of K₂CO₃ in THF as reaction solvent at80℃for 7 h.23 multisubstituted tetrahydropyrrole compounds were obtained in46%-94%yields.2.Iodine-mediated three-component[3+2]cycloaddition/oxidative aromatization cascade reaction to construct tetrasubstituted pyrroles.After investigation,we obtained the optimum reaction conditions which were:the material mole ratio was1.0:2.0:2.0,added 0.8 equivalent of iodine as a catalyst and 0.75 mmol of anhydrous K₂CO₃ as base,THF as solvent,in 80℃for 7 h of reflux reaction under oil bath,1.8equivalent of DDQ was then added as oxidant to continue the reaction for 6 h,and ultimately 20 multifunctional group substituted pyrrole compounds were obtained at a yield of 45-75%.3.31 asymmetricα,β-diaminone compounds were synthesized by iodine-promoted intermolecular diaminination between chalcone and secondary amine.The reaction conditions were investigated and optimized,including the types of solvent,base,temperature,the amount of iodine,the amount of base and add oxidant or not,etc.Finally,we received the optimum reaction conditions were:anhydrous K₂CO₃ as base,adding 1.0 equivalent of iodine,THF as solvent reaction,in 50℃,31target compounds were obtained in 15%-91%yields.Compared with the previously reported methods catalyzed by transition metals or hypervalent iodine reagents,this synthesis tactic has the advantages of easy availability of raw materials,simpler experimental operation,milder reaction conditions,wider substrate range and avoiding the use of metals,which provides an effective way for the diaminination reaction of olefin to synthesize vicinal diamine compounds.4.An effective method to synthesize theα-enaminone compounds via the formation of C（sp²）-N bond through CDC amination raction between chalcone and secondary amine compounds in the presence of KI/TBHP system was studied.We preliminarily screened catalytic system,the type of solvent,catalyst dosage,temperature,etc.It is concluded that the optimal reaction conditions,namely in the mole ratio of 1.0:2.0 of ketone and secondary amine in THF,added 1.0 equivalent of KI and 3.0 equivalent of TBHP as catalyst,which reacted at room temperature,we got12 target compounds.