Ruthenium-Catalyzed Regio-Selective Synthesis of C3-Alkylated Indoles following Transfer Hydrogenation or Borrowing Hydrogen Strategy

By employing either borrowing hydrogen or transfer hydrogenation strategy, two straightforward [Ru(p-cymene)Cl2]2-catalyzed methods for regio-selective synthesis of C3-alkylated indoles have been developed, utilizing alcohols as H atom donors or alkylating agents. The developed catalytic system could accommodate a broad substrate scope including primary/secondary aliphatic alcohols and substituted indoles, and in most cases providing good yields. Notable features of the developed system include high-activity, easy to operation and air atmosphere.