An Uncanny Dehydrogenation Mechanism: Polar Bond Control over Stepwise or Concerted Transition States
The mechanism of N-heterocycle dehydrogenation with the bifunctional (iPrPNP)Fe(CO)(H) catalyst was investigated. N-Heterocyclic substrates are completely dehydrogenated with barriers of the C−N dehydrogenation (ΔG‡ = 9.6−22.2 kcal/mol) significantly lower than barriers of the C−C dehdyrogenation (ΔG‡ = 37.4−42.2 kcal/mol). Therefore, dehydrogenation only occurs at the C−N bond. Interestingly, substrates with polarized C−N bonds entail stepwise (proton then hydride) dehydrogenation, and substrates with relatively unpolarized C−N bonds are dehydrogenated through a concerted proton/hydride transfer TS.
Gary, J. Brannon, "An Uncanny Dehydrogenation Mechanism: Polar Bond Control over Stepwise or Concerted Transition States" (2017). Faculty Publications. 56.
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