Palladium(II) in electrophilic activation of aldehydes and enones: efficient C-3 functionalization of indoles

Abstract

The regioselective C-3 alkylation of indoles with aldehydes and enones as electrophiles is catalyzed by a d8 late transition metal complex PdCl2(MeCN)2 at room temperature in the presence of air/moisture and in the absence of any additional acid/base, additive, or ligand. The active catalyst in this alkylation is an organometallic intermediate C1 which is formed from the reaction of indole with the palladium(II) pre-catalyst. The crystallographic characterization and reactivity of C1 and its analogs with indoles and surrogates is in progress.