One-pot three-step synthesis of naphtho[2,3-α]carbazole5,13-diones using a tandem radical alkylation-cyclization-aromatization reaction sequence

Article abstract of DOI:10.1002/adsc.200900789

A three-step, one-pot tandem reaction including radical nucleophilic alkylation/cyclization/ aromatization was developed using 0.3 equivalents of silver(I) acetate (AgOAc) as the catalyst and 2 equivalents of ammonium persulfate [(NH₄)₂S₂O₈] as the oxidant. This strategy is highly efficient for the assembly of pentacyclic complex carbazoles from aryl-fused bromobenzoquinones and indol-3ylpropanoic acid acids in 52-72% overall yields (three steps). This new approach provides a significant improvement over the previously reported methods and would greatly facilitate analog library construction of pentacyclic complex carbazoles and benefit further biological evaluation of these compounds.