Acid‐Catalysed or Radical‐Promoted Allylic Substitution of 2‐Methylene‐2,3‐dihydrobenzofuran‐3‐ols with Thiol Derivatives: a Novel and Expedient Synthesis of 2‐(Thiomethyl)benzofurans

Abstract

AbstractThe 2‐thiomethylbenzofuran derivatives 3 are conveniently prepared in good yields through the reactions between the readily available 2‐methylene‐2,3‐dihydrobenzofuran‐3‐ols 1 and the thiol derivatives 2 (including alkyl thiols, thiophenol, and thioacetic acid). The allylic substitution process may be either acid‐catalysed or promoted by radical initiators. In the first case, the reactions are carried out at 90 °C in 1,2‐dimethoxyethane (DME) as the solvent in the presence of H2SO4 as the proton source. The radical‐promoted reactions take place in DME at 90 °C in the presence of azobis(isobutyronitrile) (AIBN) or benzoyl peroxide (BP) as the radical initiator.