Computational Study of the Palladium‐Catalyzed Carbonylative Synthesis of Aromatic Acid Chlorides: The Synergistic Effect of PtBu3 and CO on Reductive Elimination. Issue 42 (8th September 2016)

• Record Type: Journal Article
• Authors: Quesnel, Jeffrey S.; Moncho, Salvador; Ylijoki, Kai E. O.; Torres, Gerardo Martin; Brothers, Edward N.; Bengali, Ashfaq A.; Arndtsen, Bruce A.
• Is Part Of: Chemistry. Volume 22:Issue 42(2016)
• Page Start: 15107
• Page End: 15118
• Publication Date: 2016-09-08
• Subjects: acid chloride -- carbonylation -- density functional calculations -- palladium -- reductive elimination; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201602890
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: We describe herein computational studies on the unusual ability of Pd(P t Bu3 )2 to catalyze formation of highly reactive acid chlorides from aryl halides and carbon monoxide. These show a synergistic role of carbon monoxide in concert with the large cone angle P t Bu3 that dramatically lowers the barrier to reductive elimination. The tertiary structure of the phosphine is found to be critical in allowing CO association and the generation of a high energy, four coordinate (CO)(PR3 )Pd(COAr)Cl intermediate. The stability of this complex, and the barrier to elimination, is highly dependent upon phosphine structure, with the tertiary steric bulk of P t Bu3 favoring product formation over other ligands. These data suggest that even difficult reductive eliminations can be rapid with CO association and ligand manipulation. This study also represents the first detailed exploration of all the steps involved in palladium‐catalyzed carbonylation reactions with simple phosphine ligands, including the key rate‐determining steps and palladium(0) catalyst resting state in carbonylations. Abstract : CO makes it go : Carbon monoxide in concert with the P t Bu3 ligand is found to dramatically lower the barrier to reductive elimination and the palladium‐catalyzed formation of reactive acid chlorides (see figure). These results suggest that even presumed challenging reductive eliminations can proceed with low barriers with the correct ligand design to facilitate CO association, and highlights the critical role of steric interactions in this transformation.