Deuterium-Labeling Studies on the C–H/Olefin Coupling of Aromatic Ketones Catalyzed by Fe(PMe3)4

Abstract

Deuterium-labeling experiments were performed for the Fe(PMe3)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.

Iron/Photosensitizer-Catalyzed Directed C–H Activation Triggered by the Formation of an Iron Metallacycle

“…However, these reactions require the use of stoichiometric organometallic reagents, which may potentially be incompatible with some functional groups and compromise the synthetic efficiency. The second strategy involves the use of a preformed low-valent iron complex (Scheme b). , While the stoichiometric oxidative addition of C–H bonds to low-valent iron complexes has been known for years, the application of these complexes to catalytic directed C–H functionalizations remains limited. Notably, Wang and Yoshikai have used Fe 3 (CO) 12 , while Kakiuchi ,,,, and Ackermann , have used Fe­(PMe 3 ) 4 as active iron catalysts for catalytic C–H functionalization reactions.…”