Electrochemical C-H functionalization and subsequent C-S and C-N bond formation: paired electrosynthesis of 3-amino-2-thiocyanato-α,β-unsaturated carbonyl derivatives mediated by bromide ions

An efficient paired electrosynthesis involving C-H functionalization and subsequent C-S and C-N bond formation for the assembly of valuable3-amino-2-thiocyanato-alpha,beta-unsaturated carbonyl derivatives has been developed. In the paired electrolysis, the amino and thiocyanato moieties originate from a single reagent or a combination of ammonium acetate and potassium isocyanate. The chemistry proceeds in a simple undivided cell employing a sub-stoichiometric amount of NH4Br that serves both as an inner sphere type redox catalyst and a supporting electrolyte; in this manner an additional conducting salt is not required. The reaction also works using a catalytic amount of NH4Br. Cyclic voltammetry and the results of control experiments demonstrate that the reaction proceeds via an anodically initiated C-H functionalization of the 1,3-dicarbonyl substrates that occurs via the electrochemical oxidation of bromide and simultaneous cathodic reduction of ammonium ions.