Study On The Novel Synthesis Of Carbazolones Via Hypervalent Iodine Compounds

Carbazolone derivatives abroadly exist in nature, and the carbazolones are used as important intermediates in the synthesis of some medicines and biologically active naturally occurring carbazole alkaloids. Thus the synthetic method of carbazolones has been receiving increasing attention from researchers. Based on the report of the novel synthesis of N-substituted indole ring, we proposed a new method which involves the direct carbon-nitrogen bond formation to construct carbazolone derivatives and the analogues of carbazolone: N-substituted-2-methyl-3-acetyl-indole derivetives via PIFA-mediated intramolecular cyclization.Using 2-aryl-1, 3-diones and different amines as starting materials, 3-amino-2-aryl-cyclohex-2-enone and 4-amino-3-aryl-pent-3-en-2-one were synthesized as substrates.Using 3-substitutedamino-2-aryl-cyclohex-2-enones and 4-substitutedamino-3- aryl- pent-3-en-2-ones as substrates, a series of N-substituted carbazolone derivatives and N-substituted-2- methyl-3-acetyl-indole drivetives were synthesized via intramolecular cyclization in the presence of PIFA. Using 3-amino-2-aryl- cyclohex-2-enones as substrates, a series of N-unsubstituted carbazolone derivatives were synthesized via intramolecular cyclization in the presence of PIDA. The reaction condition is mild, the workup procedure is simple.A series of carbazolone derivatives and a series of N-substituted-2- methyl- 3-acetyl-indole drivetives were obtained using this method, the substituent on the nitrogen greatly influence the yield of the target moleculars. The structure of the compounds were characterized by 1H NMR, 13C NMR and LRMS. Mechanisms were studies for the reaction process, and a possible mechanism was proposed.