Deuterium-Labeling Studies on the C-H/Olefin Coupling of Aromatic Ketones Catalyzed by Fe(PMe ₃) ₄

Deuterium-labeling experiments were performed for the Fe(PMe ₃) ₄-catalyzed C-H/olefin coupling using a deuterium-labeled aromatic ketone with various alkenes. While the reactions with a variety of alkenes provided the linear alkylation products formed via 1,2-insertion of alkene into an Fe-H bond, the reversible 2,1-insertion proceeded during the reaction highly depends on the choice of the alkene. No H/D scrambling resulting from 2,1-insertion/β-elimination was detected for the reactions with a vinylsilane and N -vinylcarbazole, but the reactions with styrenes are considered to involve rapid 2,1-insertion/ β-elimination processes to cause significant levels of H/D scrambling.