XtalFluor‐E effects the C3‐H sulfenylation of indoles to form di‐indole sulfides

A simple, regioselective synthesis of di-indole sulfides by electrophilic aromatic substitution the C3-position indoles was achieved using Xtalfluor-E as sulfenylating reagent. The addition amine bases found to have a significant effect on reaction outcome, with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) switching off reactivity XtalFluor-E, while hindered base 2,6-ditertbutyl-4-methylpyridine (DBP) led formation two di-indole-sulfur containing products, one S(II) and S(IV). optimal for accessing in high yield proved be Hünigs base, EtNiPr2. While this formed Lewis adduct did not completely quench indicating reversible coordination sulfur center. This is first report utilizing XtalFluor-E form C−S bonds our knowledge, process applicable wide range functionalized does require N1-protection.