Divergent synthesis of polythioindoles using elemental sulfur as the polysulfur source under metal-free conditions

Abstract

Here, we demonstrate the divergent synthesis of symmetrical or unsymmetrical tetrathiadiindoles and pentathiepino[6,7-b]indoles from indoles and elemental sulfur under metal-free conditions. These transformations probably involve a selective cyclization process of specific indole sites with polysulfur fragments which are in situ generated from elemental sulfur. This work features simple operation, metal-free nature, wide substrate scope, readily available starting materials, and feasible synthesis of valuable products. Furthermore, this method enables the direct assembly of active molecules that show anti-fungal activity and could be used as FIV inhibitors. Notably, temperature and oxidant play crucial roles in the selective synthesis of polythioindole derivatives.