A Novel Synthesis of Pyrrole‐2‐carboxylic Acid Derivatives by Ring Transformation of 1,2‐Thiazolium Salts through Sulfur Extrusion

Abstract

The rearrangement of an acidic N-methylene group from an exocyclic to an endocyclic position and simultaneous sulfur extrusion allows a very efficient synthesis of pyrrole-2-carboxylic acid derivatives [Eq. (a)]. These compounds may serve as lead structures for the development of new anticonvulsants, and analgesic and antiinflammatory agents as well. The novel ring transformation has already been shown to be generally applicable. R2  aryl, NRR′, SR; R3  aryl, H; R4  Ph, Me, H.