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ABSTRACT.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-Nsulfonic acid (SuSA) as catalyst for the synthesis of a series of 5,6-dihydro-2-(2-oxo-2H-chromen-3-yl)-5-phenylindolo[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.

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Kinetics and mechanism of oxidation of thioglycolic acid (TGA). Thiolactic acid (TLA) and thiomalic acid (TMA) by tripropylammonium fluorochromate (TriPAFC) have been studied in N, N-dimethyl formamide (DMF). The reaction is first order with respect to TriPAFC and thioacids (TA). p-Toluene sulfonic acid (TsOH) is used as a source of hydrogen ions. The reaction is acid catalyzed. The hydrogen ion dependence has the form: k obs = a + b [H + ]. The reaction has been studied in different percentage of DMF-acetic acid mixture. The effect of dielectric constant of the medium indicates the reaction to be of ion-dipole type. Various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of isokinetic relationship. A suitable mechanism has been proposed.