The Green Protocol For The Synthesis Of N-Arylamides And Reduction Of Aldehydes And Ketones

The current research on organic synthesis methods is aiming towards green,efficient and mild conditions.N-Arylamides and alcohol occupy an important position in organic chemistry,and the C-N bond construction and the synthesis of alcohols have attracted widespread attention.N-Arylamides are often reported to be synthesized by Chan-Lam coupling reactions,but there are some problems such as low general yield,harsh reaction conditions or longer reaction time.Therefore,it is necessary to find a green and efficient reaction system.When encountering some hydroxy compounds which are difficult to synthesize,the method of reducing the carbonyl group of aldehyde or ketone to hydroxyl group can be adopted to obtain the target products.In this study,a magnetically recoverable catalyst was prepared,and the conditions were optimized with additives,temperature and solvents.A green and efficient method for the synthesis of N-arylamide compounds and hydroxy compounds was developed respectively.The research contents are as follows:1.Based on the Chan-Lam reaction,we synthesized N-arylamides through the coupling of benzamide and arylboronic acid.We initially prepared and characterized Fe₃O₄-Cu₂O by SEM and XRD.The optimal reaction conditions obtained are as follows:Fe₃O₄-Cu₂O as the catalyst,4-dimethylaminopyridine as the ligand,KOH as the base,and DMSO as the solvent.The reaction was performed at 100?for two hours to obtain the N-phenylbenzamide in a yield of 80%.The reaction can be carried out under air conditions.and the catalyst was separated by a magnet after the reaction.The reaction activity was not greatly lost after 5catalytic cycles.It was found that this method has good selectivity in the study of the scope of substrates.Both the electron-donating and the electron-withdrawing groups on the aromatic ring can be tolerant,and a good yield is obtained.The substrates containing the electron-withdrawing groups has a higher yield than electron-donating groups.Finally,we have speculated on the coupling mechanism of benzamide and phenylboronic acid based on literature.2.The reaction of reducing aldehydes and ketones to alcohols was optimized considering solvents and reducing agents.The best reaction conditions were based on the followings:p-bromobenzaldehyde was used as a substrate,methanol as a solvent,phenylsilane as a reducing agent,and Fe₃O₄-Cu₂O as a catalyst at room temperature and air atmosphere.After the reaction,p-bromobenzyl alcohol was obtained in a yield of 84%.When other solvents were used,the reaction cannot occur.Good yields and better selectivity were obtained after expanding the substrates.When the aromatic ring contains nitro and cyano,there was no change after the reaction.This method was equally applicable to heterocyclic and aliphatic compounds.