Sulfamic acid promoted expeditious and column chromatography free synthesis of functionalized spiro [indoline-3, 7′-pyrano [3, 2-c: 5, 6-c'] dichromene]-2, 6′, 8′-trione derivatives under reflux conditions

Multicomponent synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives

Herein, we report a one-pot greener methodology for the synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives by the multicomponent reaction of arylglyoxal monohydrate, 2-amino-1,4-naphthoquinone, and indole in acetonitrile medium under reflux conditions in the presence of 10 mol% sulfamic acid as a catalyst in 20-30 min of reaction time. Three new bonds have formed (2 C-C, 1 C-N) in this methodology. Bioactive moieties such as indole, pyrrole and naphthoquinone are present in our product. This methodology is also applicable in gram-scale synthesis. A wide variety of substrates were tested to find the generality of the methodology and good yield of the products were obtained in a very short reaction time. Along with the operational simplicity of the methodology, purification process of the products is easier by simple recrystallization process. All the synthesized products were characterized by spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, and HRMS.