Activation of Elemental Sulfur by Electrogenerated Cyanomethyl Anion: Synthesis of Substituted 2-Aminothiophenes by the Gewald Reaction

摘要

The activation of elemental sulfur (S8) has been achieved by means of electrogenerated cyano-methyl anion [easily obtained by galvanostatic reduction from acetonitrile/tetraethylammonium hexa-fluorophosphate (MeCN-Et4NPF6)]. The "activated" sulfur reacted with yhdenemalononitriles to give substituted 2-aminothiophenes in very high yields. This variation of the Gewald reaction has been carried out using only catalytic amounts of electricity and supporting electrolyte. A proposed mechanism for the interaction between S8 and cyanomethyl anion is described.