Ligand Substitution, Catalyst Activation, and Oxidative Addition Studies of a Stable Dialkyl Palladium Precatalyst

Organometallics, Год журнала: 2025, Номер unknown

Опубликована: Янв. 6, 2025

Palladium-catalyzed cross-coupling reactions are indispensable in chemical synthesis, but efficient situ catalyst activation remains a persistent challenge. Current Pd(II) precatalysts often lead to inefficient activation, necessitating higher loadings and limiting selectivity. We investigated the ligand substitution mechanism of stable dialkyl complex (DMPDAB)Pd(CH2SiMe3)2 real-time using mass spectrometric monitoring. The introduction charge-tagged phosphine ligands enabled detection key catalytic intermediates identification off-cycle species. Our findings demonstrate low energy for dissociation DMPDAB reductive elimination (Me3SiCH2)2 resulting rapid formation monoligated LPd(0) species, active species oxidative addition. These mechanistic insights offer path toward developing more selective Pd-catalyzed processes, offering valuable guidance future design with improved performance.

Язык: Английский

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C2-Selective Palladium-Catalyzed C–S Cross-Coupling of 2,4-Dihalopyrimidines

Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Янв. 19, 2025

Under most conditions, 2,4-dihalopyrimidines undergo substitution reactions at C4. Here we report that Pd(II) precatalysts supported by bulky N-heterocyclic carbene ligands uniquely effect C2-selective cross-coupling of 2,4-dichloropyrimidine with thiols. The regioselectivity this reaction stands in stark contrast to ∼1500 previously reported Pd-catalyzed cross-couplings favor C4 the absence other substituents on pyrimidine ring. Selectivity catalytic system herein is extremely sensitive structure precatalyst, largely due competing C4-selective nucleophilic aromatic substitution. C2-selectivity high 1° thiols and thiophenols, a range substituted dichloropyrimidines can be used. atypical selectivity transformation may facilitate diversity-oriented synthesis, as demonstrated for derivatives an antiviral agent. these C2─Cl cleavage not take place through typical oxidative addition pathway.

Язык: Английский

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On-Demand Access to Palladium Oxidative Addition Complexes (OACs) from a Stable Organopalladate Salt

Organometallics, Год журнала: 2025, Номер unknown

Опубликована: Фев. 28, 2025

Palladium oxidative addition complexes (OACs) are state-of-the-art catalysts for many C–C and C-heteroatom cross-coupling reactions, but altering the ancillary ligand identity (i.e., phosphine, N-heterocyclic carbene) often requires a bespoke synthesis. This has limited modularity accessibility of these ideal catalysts. We report simple admixture approach combining bench-stable organopalladate salt with mono- or bidentate to generate OACs within minutes at room temperature. High yields across suite canonical reactions demonstrate "on-demand" Pd OAC strategy can function as drop-in replacement isolated well several other contemporary precatalysts. Characterization previously unknown coordinated by single NHC also highlights how this circumvent decomposition thermally sensitive that difficult access directly from oxidation reactions.

Язык: Английский

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Enhancing activity and selectivity of palladium catalysts in ketone α-arylation by tailoring the imine chelate of pyridinium amidate (PYA) ligands

Catalysis Science & Technology, Год журнала: 2024, Номер unknown

Опубликована: Дек. 18, 2024

Palladium complexes with chelating pyridinium amidate ligands are efficient catalysts for the α-arylation of ketones. Their catalytic activity depends on group at PYA, iPr-substituted pyrazole PYAs reaching high turnover frequencies.

Язык: Английский

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