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Abstract Mono‐N‐protected amino acids (MPAAs) are increasingly common ligands in Pd‐catalyzed C−H functionalization reactions. Previous studies have shown how these ligands accelerate catalytic turnover by facilitating the C−H activation step. Here, it is shown that MPAA ligands exhibit a second property commonly associated with ligand‐accelerated catalysis: the ability to support catalytic turnover at substoichiometric ligand‐to‐metal ratios. This catalytic role of the MPAA ligand is characterized in stoichiometric C−H activation and catalytic C−H functionalization reactions. Palladacycle formation with substrates bearing carboxylate and pyridine directing groups exhibit a 50–100‐fold increase in rate when only 0.05 equivalents of MPAA are present relative to PdII. These and other mechanistic data indicate that facile exchange between MPAAs and anionic ligands coordinated to PdIIenables a single MPAA to support C−H activation at multiple PdIIcenters.
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Synthesis of a Water-Soluble, Soft N-Donor BTzBP Ligand Containing Only CHON
A hydrophilic ligand that contains only C, H, O, and N substituents and uses a 6,6′-bis(1H-1,2,3-triazol-4-yl)-2,2′-bipyridine (BTzBP) structural core has been synthesized. The effect of adding water-soluble groups onto extractant ligands has been extensively studied to facilitate the efficient partitioning of 4f and transuranic 5f elements for the treatment of spent nuclear fuel. Soft, N-donor ligands exhibit greater binding affinities for the trivalent actinides over the trivalent lanthanides, making BTzBP ligands an ideal candidate in the search for extractants to be used on an industrial scale. To date, hydrophobic BTzBPs have been shown to exhibit physical and chemical properties that might be conducive to nuclear waste processing conditions. However, hydrophilic BTzBPs have yet to be reported. Herein, we show the synthesis of a hydrophilic BTzBP ligand featuring cationic water solubilizing groups attached to the bipyridal rings.
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- Award ID(s):
- 1827905
- PAR ID:
- 10171933
- Date Published:
- Journal Name:
- Synlett
- ISSN:
- 0936-5214
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1055/s-0040-1707163
