1. Dimer involvement and origin of crossover in nickel-catalyzed aldehyde-alkyne reductive couplings
- Author
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Alex J. Nett, John Montgomery, Ryan D. Baxter, K. N. Houk, M. Taylor Haynes, and Peng Liu
- Subjects
Steric effects ,Stereochemistry ,Dimer ,Crossover ,Alkyne ,010402 general chemistry ,Ligands ,01 natural sciences ,Biochemistry ,Aldehyde ,Catalysis ,Article ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Nickel ,Computer Simulation ,chemistry.chemical_classification ,Aldehydes ,Molecular Structure ,010405 organic chemistry ,Ligand ,General Chemistry ,Silanes ,0104 chemical sciences ,Ring size ,chemistry ,Intramolecular force ,Alkynes ,Dimerization ,Oxidation-Reduction - Abstract
The mechanism of nickel(0)-catalyzed reductive coupling of aldehydes and alkynes has been studied. Extensive double-labeling crossover studies have been conducted. While previous studies illustrated that phosphine- and N-heterocyclic carbene-derived catalysts exhibited differing behavior, the origin of these effects has now been evaluated in detail. Many variables, including ligand class, sterics of the ligand and alkyne, temperature, and ring size being formed in intramolecular versions, all influence the extent of crossover observed. A computational evaluation of these effects suggests that dimerization of a key metallacyclic intermediate provides the origin of crossover. Protocols that proceed with crossover are typically less efficient than those without crossover given the thermodynamic stability and low reactivity of the dimeric metallacycles involved in crossover pathways.
- Published
- 2014