Transition Metal‐Free Synthesis of β‐Carboline Substituted 1,2,3‐Thiadiazoloyl Derivatives Using Elemental Sulfur as a Sulfur Source

Abstract A transition metal‐free, I 2 ‐catalyzed C−S cross‐coupling reaction has been developed for the synthesis of β‐carboline substituted 1,2,3‐thiadiazoloyl derivatives using β‐carboline‐based enaminones, tosyl hydrazide, and elemental sulfur. The highlighted features of this methodology include the formation of C−S, S−N, and C−N bonds, the use of inexpensive and nontoxic catalyst, high efficiency, easy procedures, short reaction time, and generation of natural product inspired scaffolds with good to excellent yields (upto 89 %). All the synthesized β‐carboline substituted 1,2,3‐thiadiazoloyl derivatives ( 1 – 25 B ) were investigated for in vitro cytotoxicity against HeLa cell line. The compound 4 B emerged as the most potent anticancer agent with IC 50 values of 25.9 μM.