Mechanisms for nickel(0)/N-heterocyclic carbene-catalyzed intramolecular alkene hydroacylation: insights from a DFT study

Density functional calculations have been applied to study and elucidate nickel(0)/ N -heterocyclic carbene-catalyzed intramolecular alkene hydroacylation. The calculations showed that nickel(0)-catalyzed intramolecular alkene hydroacylation involved four potential reaction channels (I, II, III, and...

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Veröffentlicht in:Journal of molecular modeling 2017, Vol.23 (1), p.11-7, Article 11
Hauptverfasser: Meng, Qingxi, Wang, Fen
Format: Artikel
Sprache:eng
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Zusammenfassung:Density functional calculations have been applied to study and elucidate nickel(0)/ N -heterocyclic carbene-catalyzed intramolecular alkene hydroacylation. The calculations showed that nickel(0)-catalyzed intramolecular alkene hydroacylation involved four potential reaction channels (I, II, III, and IV), and pathway IV was predicted to be more favorable than the other three. Two pathways, I and II, had three steps (oxidative addition, hydrogen migration, reductive elimination), and the rate-determining step was hydrogen migration. Pathway III proceeded through oxidative cyclization, β-hydride elimination, and hydrogen migration, and the rate-determining step was β-hydride elimination. Pathway IV included four steps (oxidative cyclization, dimerization, β-hydride elimination, hydrogen migration), and the rate-determining step was again β-hydride elimination. Oxidative cyclization was easy and led to rapid dimerization, greatly reducing the free energy of β-hydride elimination. The binuclear nickelacycle intermediate was observed in Ogoshi’s experiments, and it was identified by nuclear magnetic resonance (NMR). The dominant product was the five-membered benzocyclic ketone p1 . All results agreed with Ogoshi’s experiments. Graphical Abstract Nickel(0)-catalyzed intramolecular alkene hydroacylation involved four potential reaction channels. The binuclear nickelacycle intermediate was important, and the dimerization greatly reduced the free energy of the β-hydride elimination.
ISSN:1610-2940
0948-5023
DOI:10.1007/s00894-016-3186-7