L-cysteine as sustainable and effective sulfur source in the synthesis of diaryl sulfides and heteroarenethiols

L-cysteine, a natural and essential amino acid, was employed as novel sulfur source in the synthesis of symmetrical diaryl sulfides from a variety of aryl iodides in moderate to excellent yields. A tandem three steps’ reactions including C(sp2)-S bond formation, C(sp3)-S bond cleavage and another C(sp2)-S bond formation were proposed to be involved in this conversion. This protocol was featured by broad substrate scope and good functional group tolerance. In addition, heteroarenes including benzothiazoles and benzoxazoles were successfully converted into the corresponding heteroarenethiols using L-cysteine as C-H mercaptalization reagent.