S.P.N. Sudhan

Reusable silica-bonded S-sulfonic acid catalyst for three-component synthesis of 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromenes and 2-amino-4H-pyrans in aqueous ethanol

Silica-bonded S-sulfonic acid (SBSSA)-catalyzed, facile, one-pot, three-component coupling of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) or 5,5-dimethyl-1,3-cyclohexanedione, aromatic aldehydes, and malononitrile at reflux temperature is described for preparation of 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene derivatives. 2-Amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives can also be prepared in good yield under the same experimental conditions by use of ethyl acetoacetate, aldehydes, and malononitrile. The catalyst, silica-bonded S-sulfonic acid, was reused and recycled without any loss of activity or product yield.

Aqua-mediated synthesis of acridinediones with reusable silica-supported sulfuric acid as an efficient catalyst

Abstract A simple approach to the synthesis of acridinediones via one-pot three-component condensation of an aromatic aldehyde, 5,5-dimethyl-1,3-cyclohexanedione (dimedone), and ammonium acetate or p-toluidine in water with use of silica-supported sulfuric acid as an efficient catalyst is described. Excellent yields, catalyst recovery and reusability, and easy work-up are attractive features of this green protocol. All the synthesized acridinediones were characterized on the basis of their melting-points, elemental analysis and spectral data.

Silica-bonded N-propylpiperazine sodium n-propionate as an efficient recyclable catalyst for one-pot synthesis of 2-amino-4-aryl-4H,8H-6-methyl-8-oxo- pyrano(3,2-b)pyran derivatives

An efficient and convenient method for synthesis of a series of 2-amino-4-aryl-4H,8H-6-methyl-8-oxo-pyrano[3,2-b]pyran derivatives by one-pot, three-component reaction of an aromatic aldehyde, malononitrile or a cyanoacetate, and 5-hydroxy-2-methyl-4H-pyran-4-one (allomaltol) in the presence of a catalytic amount of silica-bonded N-propylpiperazine sodium n-propionate (SBPPSP), in aqueous ethanol, is described. The method has the advantages of short reaction time, mild reaction conditions, high yields, and convenience.