A catalyst-free system for 3-sulfenylation of free (N-H) indoles with mercaptobenzoic acid under alkaline conditions

We have developed a catalyst-free system for the 3-sulfenylation of free (N-H) indoles using mercaptobenzoic acid under alkaline conditions. The use of this system provides a green, convenient, and efficient method for the synthesis of 3-sulfenylindoles in good yields and with high selectivity. This simple synthesis process was carried out in a green solvent, isopropanol/H2O, under atmospheric and catalyst-free conditions. The procedure is suitable for use with N-unprotected indoles.