1,3-Dibromo-5,5-dimethylhydantoin: a versatile catalyst for synthesis of 3,3-bis(indolyl)oxindoles

A condensation of various isatins with indole derivatives has been carried out in the presence of 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as catalyst at 50 °C in ethanol in order to form3,3-bis(indolyl) oxindoles. The products were obtained within 20-90 min by 70-96% yields. The efficacy of the procedure has been confirmed by catalyzing the condensation reaction of pyrrolewhich was used as another sort of heterocycle with indole to obtain its corresponding 3,3-bis(2-pyrrolyl)oxinole. A plausible mechanism of the condensation based on DBDMH activating rolehas also been proposed. DBDMH is an effective, commercially available, insensitive to moisture and easily handling catalyst. Simple procedure, easy work-up, mild reaction conditions, highyields and short reaction times are the highlighted points of reported method.

Keywords:

1 , 3-Dibromo-5 , 5-dimethylhydantoin , isatin , indole , 3 , 3-bis(indolyl)oxindoles