Brønsted Acid Catalyzed (3+2)‐Cycloaddition of Thioketones and Indole‐2‐Carbinols Toward Thiazolo[3,4‐a]indoles

Herein, we report a Brønsted acid catalyzed approach to access the yet unknown heterocyclic motif of thiazolo[3,4-a]indoles in one-pot reaction under very mild conditions. A broad range was generated from indole-2-methanols and thioketones with 45–99% yield good functional group tolerance. The practicality process synthetic potential products were demonstrated an upscaling experiment further transformations. Additional control experiments provided mechanistic insights into this cycloaddition.