Novel Synthesis of 4- or 6-Substituted Indirubin Derivatives

Abstract

A simple and convenient route for synthesis of a series of 4- or 6-substituted indirubin derivatives by oxidation and subsequent condensation of indoxyl and isatin is described. Acidic reaction conditions are crucial to the condensation of 4-substituted derivatives, whereas for the condensation of 6-substituted derivatives, both acidic and basic conditions work well.

Keywords:

• Acid catalyzed
• indirubin
• steric hindrance
• 4-substituted

ACKNOWLEDGMENTS

The authors are indebted to Shanghai Zhongke Qiaochang Crop Protection Inc. for the NMR spectral measurements and Shanghai Pharmaceutical Group New Hualian pharmaceutical factory for the IR spectral measurements.