Benzoyl Fluorides as Fluorination Reagents: Reconstruction of Acyl Fluorides via Reversible Acyl C–F Bond Cleavage/Formation in Palladium Catalysis
This report describes the formation of value-added acyl fluorides by means of palladium-catalyzed acyl-exchange reactions between acyl fluorides and acid anhydrides. This method allows using a simple and commercially available acyl fluoride, benzoyl fluoride, as the fluoride source for the easy and efficient preparation of a variety of more complex acyl fluorides. The results of this study suggest that this reaction proceeds via a reversible acyl C–F bond cleavage/formation at the palladium center.
In this work we have examined a series of 25 different Fischer carbene complexes of the type (CO)5CrC(X)R with X = H, OH, OCH3, NH2, and NHCH3 and R = H, CH3, CHCH2, Ph, and C⋮CH, to analyze the influence of each substituent on the molecular structure and bonding of these complexes. Energy and charge decomposition analysis of the interaction between the chromium pentacarbonyl and the carbene fragments reveal that for the metal−carbene bond donation is quantitatively more important than back-donation. However, it is the back-donation rather than donation that correlates with most geometrical and electronic parameters of the complexes studied. The reasons for the larger influence of back-donation on the molecular structure of Fischer carbene complexes are discussed.