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Abstract Palladium(II)‐catalyzed C(alkenyl)−H alkenylation enabled by a transient directing group (TDG) strategy is described. The dual catalytic process takes advantage of reversible condensation between an alkenyl aldehyde substrate and an amino acid TDG to facilitate coordination of the metal catalyst and subsequent C(alkenyl)−H activation by a tailored carboxylate base. The resulting palladacycle then engages an acceptor alkene, furnishing a 1,3‐diene with high regio‐ andE/Z‐selectivity. The reaction enables the synthesis of enantioenriched atropoisomeric 2‐aryl‐substituted 1,3‐dienes, which have seldom been examined in previous literature. Catalytically relevant alkenyl palladacycles were synthesized and characterized by X‐ray crystallography, and the energy profiles of the C(alkenyl)−H activation step and the stereoinduction model were elucidated by density functional theory (DFT) calculations.
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Creating, Preserving, and Directing Carboxylate Radicals in Ni-Catalyzed C(sp 3 )–H Acyloxylation of Ethers, Ketones, and Alkanes with Diacyl Peroxides
The reaction of Ni(II) acetate with diacyl peroxides produces high-valence Ni-species capable of catalytic oxidative acyloxylation of C(sp3)–H bonds in ethers, ketones, and alkanes. The desired esters were obtained in 20–82% yields. Computational analysis suggests that activation of the peroxide moiety produces a dynamically interconverting mixture of catalytic Ni-species in the formal Ni(III) state. Remarkably, in these species, coordination of the RCO2 group at Ni preserves radical character at the carboxylate moiety (i.e., carboxylate radical acts as an “L-ligand”), so the latter can induce fast C–H abstraction. The spirocyclopropyl moiety prevents premature radical decarboxylation via a combination of hybridization factors and stereoelectronic effects. A variety of viable C–H activation patterns were identified experimentally and computationally.
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- Award ID(s):
- 2102579
- PAR ID:
- 10408843
- Date Published:
- Journal Name:
- Organometallics
- ISSN:
- 0276-7333
- 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/10.1021/acs.organomet.2c00663
