Palladium-Catalyzed Decarboxylative Benzylation of Acetylides and Enolates

Abstract

Benzylic alkylation of enolates and acetylides has been achieved through the use of a decarboxylative benzylation strategy. Previous research in this area is often limited by the need for extended conjugation in the electrophiles that are coupled. Herein, we report that the use of 1,1'-bis(diphenylphosphino)ferrocene (dppf) ligand allows the coupling of simple benzyl electrophiles with enolates, while the use of XPhos ligand promotes the decarboxylative couplings of propiolates.

Skeletal Editing of Dibenzolactones to Fluorenes via Ni- or Pd-Catalyzed Decarboxylation

“…The key step in this process utilizes a nickel-catalyzed decarbonylation that proceeds via oxidative addition to the C­(acyl)–O bond (Scheme A). Guided by decarboxylative-intramolecular coupling reactions first described by Tsuji and Saegusa and their variants − (Scheme B), we reason that, for lactones such as dibenzo­[ c,e ]­oxepin-5­(7 H )-ones containing a benzyl ester, oxidative addition would instead occur at the benzylic Csp 3 –O bond . This would allow for decarboxylation followed by intramolecular cross-coupling to occur (Scheme C), thus enabling the skeletal editing of dibenzolactone motifs found in Graphislactone D and related natural products into fluorenes, which are important substructures in pharmaceuticals, natural products, and fluorophores …”

Pd-Catalyzed Chemoselective O-Benzylation of Ambident 2-Quinolinone Nucleophiles

“…This requirement placed significant limitation on the use of stoichiometric Ag-salts. Thus, we turned our attention to identifying a catalytic O-benzylation of 2-quinolinones based on the broad success of metal-catalyzed benzylic alkylation reactions using simple nucleophiles and related catalyzed arylations of 2-pyridones. − Initial results from our preliminary screening efforts identified several Pd-based catalysts as promising leads worthy of further development for the chemoselective O-alkylation of 2-quinolinones. A selected set of optimization data from these efforts is shown in Table using 2-quinolinone ( 1 ) and benzyl bromide ( 2 ) as model substrates.…”