Theoretical Study on the Kinetics and Thermodynamics of the Tandem Cope-Type Hydroamination and [2,3]- Meisenheimer Rearrangement Sequence

Subject Areas :

Mitra Sanie ¹ (Department of Chemistry, Borujerd Branch, Islamic Azad University, Borujerd, Ir)
Ehsan Zahedi ² (Department of Chemistry, Shahrood Branch, Islamic Azad University, Shahrood, Iran)
Seyed Hosein Ghorbani ³ (Department of Chemistry, Borujerd Branch, Islamic Azad University, Borujerd, Ira)
Ahmad Seif ⁴ (Department of Chemistry, Central Tehran Branch, Islamic Azad University, Tehran, Iran)

Received: 2022-07-27 Accepted : 2022-12-19 Published : 2022-05-22

Keywords: Meisenheimer rearrangement, Kinetics, Crossover temperature, Cope-type hydroamination, Thermodynamics,

Abstract :

Cope-type hydroamination of norbornene using N-allyl-N-methylhydroxylamine at 120℃ and THF leads to the formation of unstable dipolar N-oxide intermediate in which converts along the Meisenheimer rearrangement into a neutral product with higher stability. Kinetics and thermodynamics of this tandem reaction has been investigated at the M06-2X/aug-cc-pVTZ level of theory. The first step is exothermic and nonspontaneous (endergonic) while the second step is exothermic and spontaneous (exergonic). Disfavor effects of entropy and high temperature cause that the rate constant of the first step, despite the lower activation energy, be smaller than that of second step and the equilibrium be not towards the production of the N-oxide intermediate. The kinetic data exhibit that the forward step of Cope-type hydroamination is the rate-determining step, the overall rate constant at 120℃ is in order of 10–27 cm3 molecule–1 s–1, and its temperature dependence using the Wigner and Eckart corrections can be expressed as and , respectively.