Selective C3-Arylation of Free NH-Indoles with Pd-Modified Zeolite

Significance

An efficient heterogeneously Pd-catalyzed procedure for the fully C3-selective arylation of free NH-indoles was described. Thus, the reaction of indoles 1 (2 mmol) with aryl bromides 2 (2.2 mmol) was carried out in the presence of [Pd(NH₃)₄]²⁺/NaY (1 mol% Pd) and K₂CO₃ (6 mmol) as a base in dioxane (4 mL) under reflux for 24-48 h to give the corresponding C3-arylated products 3, where N1- or C2-arylated products were not observed.