Synthes Of Multisubstituted Carbazole And Pyrazole Nitrogen-containing Heterocycles

Nitrogen-containing heterocycles are important organic structural units,which are widely used in natural products,organic functional materials,agricultural chemistry,pharmaceutical industry and other fields.As a special structural unit,carbazole rings have great attraction in the study of organic chemistry.Meanwhile,carbazole compounds,as an important framework for the synthesis of organic functional materials,play a very important role in the fields of photochromism,organic electroluminescence and organic covalent porous materials.On the other hand,pyrazole rings widely exists in various drug molecules and natural products.Therefore,developing efficient and simple strategies to construct various nitrogen heterocyclic frameworks has attracted substatial synthetic efforts in the organic chemistry.In this thesis,we developed an efficient method for the convenient synthesis of various multisubstituted carbazoles and pyrazole compounds from?,?-alkynyl ketones and their derivatives.Firstly,under the promotion of Sn(OTf)₂,a variety of carbazole compounds are synthesized by[3+3]cycloaddition reaction of?,?-alkynyl ketones and 2-methylindoles.The cyclization proceeds through the activating methyl group at the 2-position of indole,and contructs a series of multisubstituted carbazole compounds with a free N-H bond.Then,various N-substituted pyrazole compounds were synthesized from?,?-alkynyl-N-p-toluenesulfonyl hydrazones and alcohols in the presence of sodium through the cyclization of alkynyl hydrazones.The synthetic method has the advantages of mild conditions and wide range of substrates.In this reaction,sodium alcohol not only participates in the reaction as a substrate,but also promotes the cyclization reaction as a base.In addition,it is found that the rapid synthesis of various N-alkyl substituted pyrazole compounds can be realized by preparing different sodium alcohols in situ.