The formation of disulfides by the [Fe(nta)Cl2]2− catalyzed air oxidation of thiols and dithiols

The complexes (cnt)2[Fe(nta)Cl2], where nta = nitrilotriacetate and cnt = Et4N+ or PyH+, catalyze the air oxidation of thiols to disulfides under ambient conditions. Dithiols are converted to linear and cyclic oligomers that differ in their terminal groups as a function of the counterion, cnt. Cysteine ethyl ester was converted to the corresponding cystine diethylester in high yield.