A Gold-Catalyzed Cascade Reaction Involving an Unusual Intramolecular Redox Process

A study was conducted to demonstrate a new gold-catalyzed cascade reaction involving a a redox process. The reactivity of secondary 5-hexyn-1-ol derivatives and indoles were investigated under gold-catalyzed conditions to demonstrate the cascade reaction. The investigations were conducted with the reaction of secondary alkynol derivatives and N-methylindole in the presence of a cationic gold(I) complex. The process was generated in situ by the reaction of 5 mol% of [(Ph3P)AuCl] and 5 mol% of AgSbF6 in dichloromethane as solvent at room temperature. A set of experiments were also conducted with other heteroaromatic compounds to expand the synthetic utility of the reaction. The new catalytic reaction involved initial intramolecular hydroalkoxylation reaction followed by an intramolercular hydroarylation and an intramolecular Oppenauer-type oxidation process.