Palladium enolate complexes such as (PPh₃)₂PdX(CH₂COPh) are potential intermediates for coupling reactions in which a new bond is formed between the enolate [alpha]-carbon and an sp or sp² carbon via transmetallation or electrophilic C-H activation. However, at the elevated temperatures often required for these coupling reactions, such Pd-enolate complexes are subject to first-order decomposition, and the release ofPPh₃)₂PdX, acetophenone, and other unknown Pd complexes. Kinetic decomposition studies by ¹H NMR spectroscopy were pursued to determine the mechanisms of this conversion. Our results suggest the formation of a bis-enolate complex, which results from a ligand disproportionation of the original Pd-enolate complex. When [beta]-hydrogens are present, this disproportionation competes with [beta]-hydride elimination. Deuterium labeling studies indicate that in the absence of [beta]-hydrogens, the enolate ligand receives its hydrogen via C-H activation of the phenyl group on the second enolate
Kornecki, Katherine, "Mechanistic studies of Palladium enolate complexes" (2008). Honors Project, Smith College, Northampton, MA.
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