Iodocyclization of 2‐Methylthiophenylacetylenes to 3‐Iodobenzothiophenes and their coupling Reactions under More Sustainable Conditions
Raffaella Mancuso, Melania Lettieri, Romina Strangis, Patrizio Russo, Antonio Palumbo Piccionello, Sara De Angelis, Bartolo Gabriele
Abstract
Abstract We report the first example of iodocyclization of readily available 2‐methylthiophenylacetylenes in a deep eutectic solvent (ChCl/urea 1/2, mol/mol) as recyclable and more sustainable solvent with respect to the classical VOCs employed so far. The process successfully afforded a variety of 3‐iodobenzothiophenes in good to high yields starting from differently substituted substrates, with the possibility to recycle the DES several times without appreciable lowering of the product yield. The 3‐iodothiophenes thus synthesized are known to be important precursors of biologically active molecules and functionalized heterocycles, and were successfully employed for performing representative Sonogashira and Suzuki cross‐coupling reactions. The solvent‐catalyst system could be conveniently recycled several times without any loss of activity in both coupling processes, thus further demonstrating the practical usefulness of our approach.