Allylation Of Chiral N-Acylhydrazones And [3+2] Cycloaddition Reactions Of Trifluoromethyled N-Acylhydrazones

N-Acylhydrazones,multifunctional compound,were known in early time,and have been found more and more applications in recent years in pharmaceutical,pesticides,materials and analytical reagents and other aspects.As for their application in organic synthesis,N-acylhydrazones have been often served as electrophiles for the synthesis of nitrogen-containing compounds.What’s more,N-acylhydrazones can act as stable imine surrogates in many reactions,such as allylations,cycloadditions,Mannich reactions,cyanations,and radical additions and so on.Hence,N-acylhydrazones play important roles in organic synthesis.The thesis mainly consists of the following three parts:Chapter one:The research progress of N-acylhydrazones in organic synthesisThis chapter firstly presents chemical structures,preparation and classification of N-acylhydrazones,then summuries a series of N-acylhydrazones-participated organic reactions.Chapter two:Tin powder-promoted diastereoselective allylation of chiral acylhydrazonesIn this chapter,we provided an efficient synthesis of chiral homoallylhydrazides by chiral acylhydrazones,allyl bromide with tin powder in the presence of ZnCl₂.The reaction proceeded smoothly to give the corresponding products in high yields and with good diastereoselectivities.The method uses the combination of tin powder and allylic bromide as allylation system,which avoids the use of toxic allylic stannanes while maintaining their merits,and further expands the application of tin powder in organic synthesis.Chapter three:Synthesis of trifluoromethylated pyrazolidines by[3+2]cycloaddition between trifluoromethylated N-acylhydrazones and nitroolefins under phase transfer catalysisIn this chapter,a highly efficient[3+2]cycloaddition between trifluoromethylated N-acylhydrazones and nitroolefins was explored.It was found that[3+2]cycloaddition between trifluoromethylated N-acylhydrazones and nitroolefins could proceed smoothly in the presence of potassium hydroxide under Bu₄NI as phase transfer catalysis,and a series of trifluoromethylated pyrazolidines were obtained in good to excellent yields under mild reaction conditions.Then trifluoromethylated pyrazolidines could be easily transformed into pyrazoles in the presence of CuCl₂ in high yields.Hence,[3+2]cycloaddition of trifluoromethylated N-acylhydrazones provides a new method for the preparation of potential bioactive trifluoromethylated pyrazolidines and pyrazoles.