Hong, Jiankai et al. published their research in New Journal of Chemistry in 2022 | CAS: 774-47-0

Copper(I)-catalyzed synthesis of natural alkaloid tryptanthrin and its derivatives was written by Hong, Jiankai;Zhang, Min;Shi, Liang;Liu, Peng;Guo, Yuchao;Zhao, Ting;Li, Qing X.;Yang, Liuqing. And the article was included in New Journal of Chemistry in 2022.Safety of 5,6-Difluoroindoline-2,3-dione This article mentions the following:

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 was described. Furthermore, more complicated tryptanthrin derivatives were obtained in two steps with two different isatins in one pot. This work featured 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 chem. of isatins and copper catalysis. In the experiment, the researchers used many compounds, for example, 5,6-Difluoroindoline-2,3-dione (cas: 774-47-0Safety of 5,6-Difluoroindoline-2,3-dione).

5,6-Difluoroindoline-2,3-dione (cas: 774-47-0) belongs to indole derivatives. Indole could be stereoselectively alkylated with chiral cyclopentyl sulfone reagent. Indole was synthesized in moderate yield via an o-naphthoquinone catalyzed tandem cross-coupling of substituted aniline and benzylamine under aerobic oxidation conditions.Safety of 5,6-Difluoroindoline-2,3-dione

Referemce:
Indole alkaloid derivatives as building blocks of natural products from Bacillus thuringiensis and Bacillus velezensis and their antibacterial and antifungal activity study,
Preparation of Indole Containing Building Blocks for the Regiospecific Construction of Indole Appended Pyrazoles and Pyrroles