Divergent Reactivity of Indole-Tethered Ynones with Silver(I) and Gold(I) Catalysts: A Combined Synthetic and Computational Study

Abstract

A combined synthetic and computational (DFT) study has been performed to account for the divergent reactivity of indole-tethered ynones when treated with Ag(I) and Au(I) catalysts. The two catalyst systems deliver spirocyclic indolenines and carbazoles, respectively, from the same precursors, with the reaction outcomes believed to be a result of differences in the rates of a key protodemetalation step. A ring-opening/ring-closing isomerisation process is proposed to enable the interconversion of spirocyclic and C-2 annulated indole intermediates, in contrast to the 1,2-migration mechanism tentatively proposed in previous studies.