An efficient one-pot organocatalytic synthesis of 9-(1H-indol-3-yl)-xanthen-4-(9H)-ones under mild aqueous micellar conditions

An efficient and facile l-proline-catalyzed three-component coupling of 2-hydroxybenzaldehyde, 5,5-dimethyl-1,3-cyclohexanedione (dimedone), and indole has been accomplished under mild aqueous micellar conditions to deliver a small library of 9-(1H-indol-3-yl)-xanthen-4-(9H)-ones of potential biological relevance. Under optimized conditions [10 mol % of l-proline, water (2 mL), SDS (23 mg, 0.08 mmol), rt], the reaction was highly selective toward the target compound and essentially free from competitive two-component byproduct formation.