Iron-Mediated Cleavage of Se-Se Bond for the Synthesis of α-Arylseleno Carbonyl Compounds

In the presence of iron dust, using commercial N,N-dimethylformamide (DMF) as solvent, diaryl diselenides reacted with alpha-bromo carbonyl compounds at 90 degrees C under nitrogen atmosphere to afford a series of alpha-arylseleno carbonyl compounds. The influence of temperature, reaction time, solvent and iron dosage on the reaction was investigated. The results showed that the influence of temperature on the reaction was most obvious. In addition, the influence of carbonyl substituent in alpha-bromo carbonyl compounds was also more obvious. When carbonyl substituent is phenyl, the yield was lower than that of methyl or alkoxy. A proposal mechanism is that iron dust reacted with diaryl diselenides to give the nucleophilic species ArSeFeSeAr, and nucleophilic species ArSeFeSeAr and electrophilic alpha-bromo carbonyl compounds occured nucleophilic substitution reaction to obtain the desire products. The method using the iron dust to promote the cleavage of Se-Se bond has advantages of safe non-toxic, cheap and easy to get raw materials, simple procedure.