Copper(i)-catalyzed synthesis of natural alkaloid tryptanthrin and its derivatives

A mild method for the preparation of tryptanthrin and its derivatives by copper(i) catalysis with two identical isatins in the presence of KHCO3 as a base is described. Furthermore, more complicated tryptanthrin derivatives are obtained in two steps with two different isatins in one pot. This work features readily available starting materials, mild reaction conditions, simple operation, good functional group tolerance, high yields and selectivity. This transformation not only provided a new method to access tryptanthrin and its derivatives, but also enriched the chemistry of isatins and copper catalysis.

Automated summary

This study describes a mild method for preparing tryptanthrin and its derivatives using copper catalyst with two identical isatins and KHCO3 as a base. More complex tryptanthrin derivatives were also obtained in two steps using two different isatins in one pot. The research highlights the use of readily available starting materials, mild reaction conditions, simple operation, good functional group tolerance, and high yields and selectivity. This transformation not only provides a new method for accessing tryptanthrin and its derivatives but also enriches the chemistry of isatins and copper catalysis.