Sequential O-H/C-H Bond Insertion of Phenols Initiated by the Gold(I)-Catalyzed Cyclization of 1-Bromo-1,5-enynes.

The development of a sequential O-H/C-H bond functionalization of phenols initiated by the cationic gold(I)-catalyzed cyclization of 1-bromo-1,5-enynes to produce (2-bromocyclopent-2-en-1-yl)phenols is reported. This unprecedented domino transformation efficiently proceeds under mild conditions (5 mol % of (t-Bu)3PAuNTf2, CH2Cl2, 0-23 °C) via an intermediate aryl alkyl ether which collapses at ambient temperature to undergo a 1,2-hydride shift followed by C-H insertion of the phenol. [ABSTRACT FROM AUTHOR]