Palladium-Catalyzed Direct C-H Alkylation of Electron-Deficient Pyrrole Derivatives

Abstract

The apparent and the real: What looks like a Friedel–Crafts alkylation reaction of electron-deficient pyrroles is actually a PdII-catalyzed, norbornene-mediated CH activation reaction, in which the alkylation of the pyrrole core occurs by reductive elimination. As well as ethyl-1H-pyrrole-2-carboxylate (see scheme), several other 2,3-disubstituted pyrroles underwent the selective C5 alkylation in good yield.