Study On The Chlorination Reaction Of Hydrazones By Using Of Trichloroisocyanuric Acid As Chloride Source

Nitrile imines,which are usually generated from hydrazonyl halides in the presence of base,are great 1,3-dipoles that can undergo [3+2],[3+3] and [3+4]cycloadditions with dipolarophiles to afford many bioactive five-member,six-member and even seven-member heterocycles.Nitrile imines can also undergo coupling reaction with dipolarophiles or organometallic reagents to generate hydrazone compounds with complicated structure.In general,N-arylhydrazonyl chlorides can be synthesized from chlorination reaction by using carbon tetrarchloride,phosphorus pentachloride,thionyl chloride,chlorine gas and N-chlorosuccinimide(NCS)et al as chloride source.Among them,NCS is a better chloride reagent,and other chloride sources have some disadvantages such as poor reaction selectivity,many side reactions,and harsh reaction conditions.Therefore,it is still necessary to explore a more simple and efficient method for the synthesis of N-arylhydrazonyl chlorides.On the other hand,trichloroisocyanuric acid is a highly efficient and stable chloride source due to a high active chlorine content(91.5%)in its molecule,which makes trichloroisocyanuric acid-promoted the reactions have good atomic economy.In the meanwhile,the by-product isocyanuric acid produced in the reaction can be reproduced trichloroisocyanuric acid to be used in the further reaction,which accord with the principle of green chemistry.In this paper,a new method for the synthesis of N-arylhydrazonyl chlorides and N-aryltrifluoroacetohydrazonyl chlorides from the reaction of N-arylhydrazones or N-aryltrifluoroacetohydrazones and trichloroisocyanuric acid was developed.Besides,since pyrazole compounds have been widely used in the fields of pesticide,medicine and material science,the synthesis of trifluoromethylated pyrazole compounds by[3+2] cycloaddition reaction between trifluoromethylated N-acylhydrazones and alkynes also was explored in this paper.The thesis mainly consists of the following there parts:Chapter one: Advances in the application of hydrazonyl chlorides in organic synthesisThis chapter firstly described the various synthetic methods of hydrazonyl chlorides;then mainly summarized reactions of hydrazonyl chlorides in organic synthesis.Chapter two: The study on the chlorination reaction of hydrazones by using of trichloroisocyanuric acid as chloride sourceThe chlorination reaction of hydrazones and N-aryltrifluoroacetohydrazones by using trichloroisocyanuric acid as chlorine source was investigated,and a series of N-arylhydrazonyl chlorides and N-aryltrifluoroacetohydrazonyl chlorides were obtained in high yields.This method had advatages of easy operation,short reaction time,mild conditions and the use of stable and cheap chlorine source,which provides an efficiant method for the synthesis of N-arylhydrazonyl chlorides and N-aryltrifluoroacetohydrazonyl chlorides.Chapter three: The study on [3+2] cycloaddition reaction between trifluoromethylated N-acylhydrazones and alkynesIn this chapter,the [3+2] cycloaddition reaction between trifluoromethylated N-acylhydrazone and phenylacetylene was initially explored to afford trifluoromethylated pyrazole compound with 51% yield.The further exploration of substrate scope of the cycloaddition is underway.