Study On Synthesis And Application Of1,2,3,9-4H-carbazol-4-one

Carbazolone derivatives are widely found in nature, and they are very important building blocks in the total synthesis of some drugs and natural biologically active carbazole alkaloids. In recent years they have drawn a great deal of interest from the scientific community. Currently, many methods are available in the literature that describes the synthesis of carbazolones, among them Fischer indole synthesis and organometallic-catalyzed synthesis are the most common and conventional methods employed in this area. However, these methods require complex raw materials, expensive catalysts and harsh reaction conditions.In response to these problems, a mild, effective and easy workup method to synthesize1,2,3,9-4H-carbazol-4-one was designed in this paper.In this paper,2-nitroaniline as the starting material reacted to2-nitroiodobenzene through Sandmeyer reaction, and then reacted with1,3-cyclohexanedione via nucleophilic aromatic substitution reaction to produce3-hydroxy-2-(2-nitrophenyl)cyclohexenone. The latter was then reduced and cycled to generate1,2,3,9-4H-carbazol-4-one with iron power and acetic acid. The influence of reaction conditions, ratio of substrates, reaction temperature and reaction time on the yield were studied. At last the optimum reaction conditions to give the target compounds in high yield were developed.The application of1,2,3,9-4H-carbazol-4-one in organic synthesis was also studied in this paper. Firstly the compound underwent N-methylation reaction, Mannich reaction and condensation reaction to give Ondansetron as an antiemetic. At the same time the influence of different reaction conditions on the yield was investigated and the optimum reaction conditions to give the target compound Ondansetron in high yield was found. Secondly4-hydroxycarbazole was prepared by dehydrogenation, which is an important intermediate in the synthesis of Carvedilol as an anti-hypertension drug. Thirdly a series of N-substituted-carbazolone derivatives were synthesized, which have an important application value and significance in the pharmaceutical and chemical fields. The title compounds and intermediates were certified by NMR, MS and IR.