The gold-catalyzed reaction of 2-alkynyl-phenylamines with alpha,beta-enones represents a new general one-pot entry into C-3-alkyl-indoles by sequential reactions. Gold-catalyzed sequential cyclization/alkylation, N-alkylation/cyclization, or N-alkylation/cyclization/alkylation reactions leading to different indoles can be directed by changing the 2-alkynyl-phenylamine 1/alpha,beta-enone 3 ratio and the reaction temperature. Unusual gold-catalyzed rearrangement reaction of indoles are observed at 140 degrees C. New gold-catalyzed formation of propargyl-alkyl ether under mild conditions and the hydration reaction of N-acetyl-2-ethynyl-phenylamine are reported.
Gold(III)-Catalyzed Annulation of 2-Alkynylanilines: A Mild and Efficient Synthesis of Indoles and 3-Haloindoles
Gold(III)-catalyzed annulation of 2-alkynylanilines in EtOH or EtOH-water mixtures at room temperature gives indoles derivatives in good yields. One-flask protocol for the gold-catalyzed conversion of 2-alkynylanilines to 3-bromo and 3-iodoindoles is also reported.