Versatile and Highly Efficient trans‐[Pd(NHC)Cl2(DMS/THT)] Precatalysts for C−N and C−C Coupling Reactions in Green Solvents. Issue 14 (11th April 2022)

• Record Type: Journal Article
• Authors: Liu, Yaxu; Voloshkin, Vladislav A.; Scattolin, Thomas; Peng, Min; Van Hecke, Kristof; Nolan, Steven P.; Cazin, Catherine S. J.
• Is Part Of: European journal of organic chemistry. Volume 2022:Issue 14(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-11
• Subjects: Buchwald-Hartwig amination -- cross-coupling -- N-Heterocyclic carbenes -- Palladium -- cross-coupling; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.202200309
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract: A straightforward synthetic procedure to well‐defined, air‐ and moisture‐ stable trans ‐[Pd(NHC)Cl2 (DMS/THT)] (NHC=IPr, SIPr, IMes, IPr Cl, IPr*, IPr # ) pre‐catalysts is reported. These complexes were obtained by reacting NHC ⋅ HCl imidazolium salts with trans ‐[PdCl2 (DMS/THT)2 ] precursors with the assistance of the weak base K2 CO3 in green acetone at 40 °C. The scalability of this protocol was demonstrated. The catalytic activity of the synthesized complexes was studied in the Buchwald‐Hartwig and Suzuki‐Miyaura reactions. Remarkably, most of the synthesized complexes exhibit higher catalytic activity with respect to their PEPPSI congeners in the Buchwald‐Hartwig amination in 2‐MeTHF. In particular, complex trans ‐[Pd(IPr # )Cl2 (DMS)] enabled the coupling of various (hetero)aryl chlorides and primary/secondary amines with a 0.2 mol% catalyst loading. In addition, trans ‐[Pd(IPr)Cl2 (DMS)] showed excellent performance in the room‐temperature Suzuki‐Miyaura reaction involving various (hetero)aryl chlorides and aryl boronic acids. In summary, the synthesized complexes, especially trans ‐[Pd(NHC)Cl2 (DMS)], can be considered as greener alternatives to classical PEPPSI type catalysts based on the lower toxicity of the throw‐away DMS ligand compared to 3‐chloropyridine. Abstract : A novel family of air‐ and moisture‐stable trans ‐[Pd(NHC)Cl2 (DMS/THT)] was synthesized using a simple and eco‐friendly synthetic protocol. These catalysts displayed outstanding performance in Buchwald‐Hartwig and Suzuki‐Miyaura reaction in green solvents.