The Gelatinous Pulp of the Fruit of Dillenia indica: An Efficient Catalyst for the Synthesis of Polyfunctionalized Indole Derivatives.

INTRODUCTION

This study reports a green and sustainable protocol for synthesizing polyfunctionalized indole derivatives. It involves the use of the gelatinous pulp of Dillenia indica fruit as the catalyst.

METHOD: The gelatinous component from fresh and mature fruit of Dillenia indica is directly used as the catalyst. The mixture of the reactants along with the catalyst is magnetically stirred at 60°C in water. After equilibrium is achieved, the product is extracted with ethyl acetate, followed by recrystallization using an ethanol/diethyl ether mixture.

RESULTS

Syntheses of twelve compounds in moderate to high yields have been reported. The catalyst can be reused up to the third cycle without compromising yield. The catalytic activity of Dillenia indica fruit gel has been compared with previously reported bio-based catalysts.

DISCUSSION: The data clearly indicate that the newly discovered catalyst surpasses other catalysts in several aspects, including energy efficiency, shorter reaction time, catalyst complexity, and the use of green solvents. Without the catalyst, the yield is limited to about 30%, but the catalyst helps to afford yields well over 80%. The catalyst does not work in organic solvents.

CONCLUSION

The catalytic activity of the gel from the fruit of Dillenia indica has been established beyond doubt. The catalyst is inexpensive and reusable. By harnessing the unique catalytic activity of this bio-based catalyst, a sustainable protocol for the synthesis of highly functionalized heterocycles has been developed. The substrate scope of the protocol is broad.