Clay (Montmorillonite K10) Catalysis of the Michael Addition of α,β-Unsaturated Carbonyl Compounds to Indoles: The Beneficial Role of Alcohols

Summary. The Michael addition of methylvinylketone to indole can be performed under smooth conditions by running the reaction in the presence of an acidic clay catalyst (K10 Montmorillonite) and an aliphatic alcohol such as ethanol or 2-propanol. Presence of an alcohol along with a polar solvent (nitromethane) in the reaction medium considerably improves the reaction.