Succinimide-N-sulfonic acid as an efficient recyclable catalyst for the synthesis of some fused indolo pyrano pyrimidinone derivatives
A new, simple, thermally efficient and solvent-free condensation of 2-amino-4,5-dihydro-4-phenylpyrano[3,2-b]indole-3-carbonitrile derivatives with coumarin-3-carboxylic acid employing succinimide-N-sulfonic acid (SuSA) as catalyst for the synthesis of a series of 5,6-dihydro-2-(2-oxo-2H-chromen-3-yl)-5-phenyl-indolo[2',3':5,6]pyrano[2,3-d]pyrimidin-4(3H)-one derivatives is described. This method has the advantages of high yield, simple methodology, and short reaction time, as well as being green in terms of avoiding the use of toxic catalysts and solvents. Furthermore, the catalyst could be recycled and reused four times without significant loss of activity. Thiourea dioxide (TUD) catalyzed efficient three-component coupling reactions of aromatic aldehydes, 3-hydroxyindole and malononitrile in water at 70 ºC was described as the preparation of 2-amino-4,5-dihydro-4-phenylpyrano[3,2-b]indole-3-carbonitrile derivatives.
KEY WORDS: Succinimide-N-sulfonic acid, Thiourea dioxide, Coumarin-3-carboxylic acid, Indolo pyrano pyrimidineone derivatives
Bull. Chem. Soc. Ethiop. 2015, 29(3), 457-471.