Copper Catalyzed Isomerization Of O-haloaryl N-sulfonyl Hydrazide And Cyclization To Synthesize 1H-carbazole Compounds

1H-indazole is an important compound which possesses a wide range of biological activities,including anti-inflammatory,anti-cancer,antidepressant,anti-HIV and antibiotic activity.Therefore,the study on the synthesis of 1H-indazole has attracted considerable interest and a great deal of effort has been devoted to the development of effective methods for the construction of the 1H-indazole backbone.Conventional methods for the synthesis of 1H-indazole compounds are diazotization or nitrosylation of aniline or cycloaddition of azide compounds.These methods generally require highly toxic or labile agents such 4s hydrazine,nitro,diazo or azide,and require very harsh reaction conditions.One of the most elegant routes in the preparation of 1H-indazole is the catalytic cyclization of o-haloaryl N-sulfonylhydrazone.At present,some research groups have reported the synthesis of 1H-indazole compounds with Z-o-haloaryl N-sulfonylhydrazone as starting material,but E-o-haloaryl N-sulfonylhydrazone is still not suitable.The isomerization of C=N double bond in hydrazones has drawn considerable attentions in the chemistry community due to its potential applied in a broad range of chemical transformations.In general,the isomerization of such double bonds can be achieved by means of two processes,either photochemically or thermally.In this thesis,we propose a new isomerization method.The isomerization of the C=N double bond was achieved with Cu(OAc)2·H2O under mild conditions,affording a new approach for the preparation of 1H-indazole via the efficient intramolecular C-N bond coupling of a mixture of E/Z o-haloaryl N-sulfonylhydrazone.Compared with previous researches,this method of synthesizing 1H-indazole has the advantages with low cost,easy operation,high yield and wide substrate range.This method has also been proved that this reaction system is suitable for the amount of grams,so it has a good application value.This method provides the convenience for the synthesis of such compounds.