The Synthesis Of 3,4-dihydroquinoxalin-2(1H)-Ones Promoted By Tin Powder

3,4-dihydroquinoxalin-2(1H)-one,as an important nitrogen-containing heterocyclic,widely exist in natural products,pharmaceutical molecules and functional materials.It has been found that when substituents are attached to 3,4-dihydroquinoxalin-2(1H)-one at 3,4 positions,the activity of these compounds can be further enhanced.The common substituents are alkyl,alkynyl,aryl,etc.However,it has not been reported that there are allylic compounds in 3,4-dihydroquinoxalin-2(1H)-one.On the other hand,allyl organotin reagent is widely used in organic synthesis.Among allylation reagents,allyl organotin reagen is widely used in organic synthesis because of its good stability to heat,water and oxygen,and good tolerance to functional groups.In recent years,the allylation promoted by tin powder has attracted the attention of chemists.In the process of reaction,allylstannanes is directly generated from tin powder and allylbromine in situ.This method not only retains the advantages of organotin reagent,but also avoids the tedious reagent preparation process and the toxicity of organotin reagent.Based on these advantages,we explored the synthesis of 3,4-dihydroquinoxalin-2(1H)-one derivatives promoted by tin powder.The thesis is mainly composed of the following three charpters:Chapter one: The research and development of organic synthesis promoted by tin powderThis chapter mainly describes the organic reactions promoted by tin powder,such as allylation,propargylation,cyanation and carbonylation,and summarizes its application in organic synthesis.Chapter two: Synthesis of 3,4-dihydroquinoxalin-2(1H)-ones promoted by tin powderIn this chapter,the allylation of quinoxalin-2(1H)-ones with allyl bromide derivatives promoted by tin powder was studied,and the multi substituted 3,4-dihydroquinoxalin-2(1H)-ones were synthesized.In the reaction,by adjusting the molar ratio of tin powder to allyl bromide,we can selectively realize the mono allylation or diallylation of quinoxalin-2(1H)-ones,which has the advantages of simple operation and high selectivity.In this method,allyltin reagent is produced in situ by the combination of tin powder and allyl bromide,which avoids the use of traditional organotin reagent and further expands the application of tin powder in organic synthesis.Chapter three: Synthesis of pyrazolidin-3-one compounds promoted by tin powderIn this chapter,we first explored the synthesis of 2-bromoacetylhydrazine as the raw material,and obtained 2-bromoacetylhydrazine protected by tert butoxycarbonyl;then,N-bromoacetylhydrazone was successfully synthesized through the substitution reaction between bromoacetyl bromide and pchloroacetophenone hydrazone.Finally,the synthesis of pyrazolidin-3-ones from N-bromoacetylhydrazone promoted by tin powder was studied.