Alkene-Coordinated Palladium(0) Cross-Coupling Precatalysts: Comparing Oxidative Addition and Catalytic Reactivity for Dimethyl Fumarate and Maleic Anhydride Stabilizing Ligands

Thomas, Gilian T.; Litman, Jared Z.; Ho, Dang Binh; Huang, Jingjun; Blonska, Kalina; Schley, Nathan D.; Leitch, David C.

doi:10.1021/acs.organomet.4c00065

Cited by 1 publication

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References 117 publications

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“…In summary, we have developed an easily prepared, bench-stable, and versatile Pd II dialkyl complex ( 1 ) suitable for OAC generation and cross-coupling catalysis that is complementary to our recently reported Pd 0 sources. , Complex 1 is thermally stable and can be handled without the need for a glovebox. It also exhibits good solubility and solution stability in a range of solvents, with minimal decomposition observed over 2 days at room temperature under air.…”

Section: Discussionmentioning

confidence: 95%

A Thermally Stable, Alkene-Free Palladium Source for Oxidative Addition Complex Formation and High-Turnover Catalysis

Huang,

Ho,

Gaube

et al. 2024

Organometallics

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Oxidative addition complexes play a crucial role in Pdcatalyzed transformations. They are not only key catalytic intermediates but also powerful and robust precatalysts, and effective reactants for late-stage functionalization of complex molecules. However, accessing a given oxidative addition complex is often challenging due to a lack of effective and stable palladium sources with the correct reactivity. Herein, we report an easily prepared and bench-stable Pd(II) dialkyl complex, DMP DAB−Pd−BTSM ( DMP DAB = N, N′-bis(2,6-dimethylphenyl)diazabutadiene; BTSM = bis-(trimethylsilylmethyl)), that is a versatile precursor for generating Pd(II) oxidative addition complexes and is highly active as a Pd source for in situ catalyst formation in cross-coupling reactions. A crucial aspect of this structure is the absence of alkene-based stabilizing ligands common to other Pd precursors. We demonstrate the utility of this precursor in the formation of several Pd(II) complexes, including phosphine and diimine-ligated oxidative addition complexes, and in high-turnover-number catalysis of C−O, Suzuki, and Heck coupling reactions. used to generate specific Pd 0 dimers of the form [(μ-COD)Pd(L)] 2 (D). These dimers are active precatalysts in challenging nucleophilic fluorinations as well as precursors to the aforementioned OACs; 18,23−25 However, poor solubility, solution instability, and air sensitivity limit their broader application. 23 Another OAC precursor is (COD)Pd-(CH 2 CMe 2 C 6 H 4 ) (E), an air-stable palladacycle first prepared by Caḿpora, Palma, and co-workers, 26 and recently exploited for OAC formation by Buchwald and co-workers. 27 However, its lower reactivity means that pretreatment of E with ligands to generate [(μ-COD)Pd(L)] 2 is required prior to the addition of aryl halides. Finally, a common issue with all of these precursors is that the dissociated alkene (dba or COD) can act as a competitive ligand, resulting in catalyst inhibition and/or challenging formation/purification of the desired OAC. 28 Here, we report an easily prepared, stable, and versatile Pd II dialkyl compound for OAC generation and in situ catalyst formation: DMP DAB−Pd−BTSM (1, Figure 1; DMP DAB = N, N′-bis(2,6-dimethylphenyl)diazabutadiene; BTSM = bis-Special Issue: Applied Organometallic Chemistry

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Section: Discussionmentioning

confidence: 95%