A highly efficient method for the synthesis of unsymmetrical spiro[4H-pyran-3,3-oxindole] is reported by three-component condensation of isatin, malonitrile and dimedone in the presence of catalytic amount of 1,3-dibromo-5,5-dimethyl hydantoin (DBDMH); High yields of products, short reaction times the use of non-toxic solvent and easy work-up in combination with commercial availability, low cost and non-toxicity of the catalyst make this work eco-friendly and commercially acceptable.
Journal of Chemical and Pharmaceutical Research.
2018.