Trifluoromethylthiolation of Aryl Iodides and Bromides Enabled by a Bench‐Stable and Easy‐To‐Recover Dinuclear Palladium(I) Catalyst

Abstract

While palladium catalysis is ubiquitous in modern chemical research, the recovery of the active transition-metal complex under routine laboratory applications is frequently challenging.D escribed herein is the concept of alternative cross-coupling cycles with am ore robust (air-, moisture-, and thermally-stable) dinuclear Pd I complex, thus avoiding the handling of sensitive Pd 0 species or ligands.Highly efficient C À SCF 3 coupling of ar ange of aryl iodides and bromides was achieved, and the recovery of the Pd I complex was accomplished via simple open-atmosphere column chromatography. Kinetic and computational data support the feasibility of dinuclear Pd I catalysis.Anovel SCF 3 -bridged Pd I dimer was isolated, characterized by X-ray crystallography,a nd verified to be ac ompetent catalytic intermediate.

Palladium(I) Dimer Enabled Extremely Rapid and Chemoselective Alkylation of Aryl Bromides over Triflates and Chlorides in Air

“…[19] Thed inuclear Pd I dimers may either react directly with aryl halides or act as aprecursor for monophosphine Pd 0 .Inshort, the precise mode of reactivity is highly dependent on whether the coupling partner can function as ab ridging unit in the dinuclear entity. [13,20] For related dinuclear Ni I complexes,t here has been very recent evidence that carbon-based bridges may in fact be possible. [21] We calculated the predicted selectivities for an n-propylbridged Pd I dimer,w hich indicated ac lear C À Br addition preference.B oth C À Cl and C À OTf are predicted to be significantly disfavored (by DDG°= 5.8 and 2.8 kcal mol À1 ).…”

“…[13] If the alkyl coupling partner was incorporated as the bridging unit via iodide/alkyl exchange in the dinuclear entity,t he resulting transient alkyl-bridged Pd I dimer might selectively react and also allow us to circumvent the intermediacyo f[ Pd II ]-alkyl species and potential side reactions.T hus,w et ested the airstable Pd I dimer 1 (2.5 mol %) in the coupling of substrate 2a with n-butylzinc chloride at room temperature in toluene. [14] Ther eaction was extremely rapid, having reached full conversion of 2a in less than 5min reaction time (see Figure 2.…”

Hoch effiziente C‐SeCF3‐Kupplung von Aryliodiden durch einen luftbeständigen zweikernigen PdI‐Katalysator

“…[5] Unter Verwendung von 5Mol-% des Iod-verbrückten Pd I -Dimers 1 und (Me 4 N)SeCF 3 (2.0 ¾quiv.) in Toluol bei 40-60 8 8Ck onnten wir eine Reihe von Aryliodiden in deren zugehçrige SeCF 3 -Verbindungen umwandeln.…”

“…[5] Unsere Mithilfe von DFT-Rechnungen wurde getestet, ob die beobachtete Reaktivität mit einem Mechanismus überein-stimmt, der eine direkte oxidative Addition von 4 an das Dimer 3 umfasst. Zur Berechnung der Energie verwendeten wir M06L in Kombination mit dem impliziten Solvatisierungsmodell CPCM (zur Beschreibung von Toluol) sowie dem Basissatz def2-TZVP.…”

“…Zur Berechnung der Energie verwendeten wir M06L in Kombination mit dem impliziten Solvatisierungsmodell CPCM (zur Beschreibung von Toluol) sowie dem Basissatz def2-TZVP. [5] Die Geometrien wurden mittels B3LYP optimiert. [24] Eindeutig zweikernige Übergangszu-stände für die oxidative Addition wurden gefunden, von denen die Addition von ArI 4 an 3 in Abbildung 3g ezeigt wird.…”