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1. N ₂ Phos – an easily made, highly effective ligand designed for ppm level Pd-catalyzed Suzuki–Miyaura cross couplings in water

   https://doi.org/10.1039/D0SC00968G  

   Akporji, Nnamdi; Thakore, Ruchita R.; Cortes-Clerget, Margery; Andersen, Joel; Landstrom, Evan; Aue, Donald H.; Gallou, Fabrice; Lipshutz, Bruce H. (May 2020, Chemical Science)

   null (Ed.)

   A new biaryl phosphine-containing ligand from an active palladium catalyst for ppm level Suzuki–Miyaura couplings, enabled by an aqueous micellar reaction medium. A wide array of functionalized substrates including aryl/heteroaryl bromides are amenable, as are, notably, chlorides. The catalytic system is both general and highly effective at low palladium loadings (1000–2500 ppm or 0.10–0.25 mol%). Density functional theory calculations suggest that greater steric congestion in N 2 Phos induces increased steric crowding around the Pd center, helping to destabilize the 2 : 1 ligand–Pd(0) complex more for N 2 Phos than for EvanPhos (and less bulky ligands), and thereby favoring formation of the 1 : 1 ligand–Pd o complex that is more reactive in oxidative addition to aryl chlorides. 

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2. An environmentally responsible 3-pot, 5-step synthesis of the antitumor agent sonidegib using ppm levels of Pd catalysis in water

   https://doi.org/10.1039/c9gc03495a  

   Takale, Balaram S.; Thakore, Ruchita R.; Kong, Fan Yi; Lipshutz, Bruce H. (November 2019, Green Chemistry)

   The current industrial approach to sonidegib utilizes wasteful organic solvents and relies on high loadings of endangered Pd. This anticancer drug can now be synthesized in 5 steps using only 3 pots, along with ppm levels of a Pd catalyst, all done in water at ambient temperatures. 

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3. Coupling the chemical reactivity of bimetallic surfaces to the orientations of liquid crystals

   https://doi.org/10.1039/d1mh00035g  

   Szilvási, Tibor; Yu, Huaizhe; Gold, Jake I.; Bao, Nanqi; Wolter, Trenton J.; Twieg, Robert J.; Abbott, Nicholas L.; Mavrikakis, Manos (July 2021, Materials Horizons)

   null (Ed.)

   The development of responsive soft materials with tailored functional properties based on the chemical reactivity of atomically precise inorganic interfaces has not been widely explored. In this communication, guided by first-principles calculations, we design bimetallic surfaces comprised of atomically thin Pd layers deposited onto Au that anchor nematic liquid crystalline phases of 4′- n -pentyl-4-biphenylcarbonitrile (5CB) and demonstrate that the chemical reactivity of these bimetallic surfaces towards Cl 2 gas can be tuned by specification of the composition of the surface alloy. Specifically, we use underpotential deposition to prepare submonolayer to multilayers of Pd on Au and employ X-ray photoelectron and infrared spectroscopy to validate computational predictions that binding of 5CB depends strongly on the Pd coverage, with ∼0.1 monolayer (ML) of Pd sufficient to cause the liquid crystal (LC) to adopt a perpendicular binding mode. Computed heats of dissociative adsorption of Cl 2 on PdAu alloy surfaces predict displacement of 5CB from these surfaces, a result that is also confirmed by experiments revealing that 1 ppm Cl 2 triggers orientational transitions of 5CB. By decreasing the coverage of Pd on Au from 1.8 ± 0.2 ML to 0.09 ± 0.02 ML, the dynamic response of 5CB to 1 ppm Cl 2 is accelerated 3X. Overall, these results demonstrate the promise of hybrid designs of responsive materials based on atomically precise interfaces formed between hard bimetallic surfaces and soft matter. 

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4. Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions

   https://doi.org/10.1002/adsc.202000483  

   Martinez, Erin_E; Jensen, Christopher_A; Larson, Alexandra_J_S; Kenney, Karissa_C; Clark, Kyle_J; Nazari, S_Hadi; Valdivia‐Berroeta, Gabriel_A; Smith, Stacey_J; Ess, Daniel_H; Michaelis, David_J (June 2020, Advanced Synthesis & Catalysis)

   Abstract We report that treatment of several 2‐diphenylphosphinoimidazoles with Pd(II) salts generates monosubstituted N−H NHC−Pd complexes via insertion into the C−P bond. Removal of the N−H proton in situ leads to anionic (X‐type) or imidazolyl‐Pd complexes that are highly stable and catalytically active, achieving up to 340,000 turnovers at 1 ppm catalyst loading in Suzuki‐Miyaura reactions. DFT‐calculated Tolman electronic parameters for the sterically small ligands suggest that these ligands are significantly more donating than traditional NHCs, which provides a rationale for rapid cross‐coupling catalysis. Excellent reactivity is also demonstrated in Sonogashira reactions. magnified image 

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5. Suzuki‐Miyaura Cross‐Coupling of Amides using Well‐Defined, Air‐Stable [(PR ₃ ) ₂ Pd(II)X ₂ ] Precatalysts

   https://doi.org/10.1002/adsc.202000122  

   Ma, Siyue; Zhou, Tongliang; Li, Guangchen; Szostak, Michal (April 2020, Advanced Synthesis & Catalysis)

   Abstract A versatile method for the Suzuki‐Miyaura cross‐coupling of amides using highly active, well‐defined, and air‐stable Pd−phosphine precatalysts is reported. Most notably, the method represents the first example of using practical and operationally‐simple Pd(II)−phosphine precatalysts in the emerging amide bond cross‐coupling manifold. The reactions are efficient at 0.10 mol% loading, furnishing biaryl ketones with high chemoselectivity for N−C(O) bond cleavage. This versatile method enables for the first time to achieve Pd−phosphine‐catalyzed cross‐coupling of amides at ppm loading. This C−N cross‐coupling can be used to efficiently furnish pharmaceutical intermediates by orthogonal Pd‐catalyzed cross‐couplings. We fully expect that operationally‐simple [(PR₃)₂Pd(II)X₂] precatalysts as effective triggers for N−C(O) cross‐coupling will be of broad synthetic and catalytic interest. magnified image 

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