Synergistic Cooperative Effect of Sodium borohydride-Iodine Towards Cascade C-N and C-S/Se Bond Formation: One-pot Regioselective Synthesis of 3-Sulfenyl/selenyl Indoles and Mechanistic Insight

In this work, a new strategy to synthesize 3-sulfenyl/selenyl indole is reported wherein LC-MS reveals a novel insight into synergistic cooperative effect of NaBH4-I-2 which allows cascade C-N and C-S/C-Se bond formations via reduction-nucleophilic cyclization-chalcogenylation, three steps in one-pot, towards regioselective synthesis of diverse 3-chalcogenyl indoles including 5-bromo-3-[(3,4,5-trimethoxyphenyl)thio]-1H-indole, a known lead anticancer compound, directly from 2-amino-phenacylchlorides and thiophenols or disulfides/diselenides in aqueous dioxane under transition-metal-free condition.