Posts Tagged ‘Imine’

σ or π nucleophilic reactivity of imines? A mechanistic reality check using substituents.

Sunday, October 9th, 2016
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Previously, a mechanistic twist to the oxidation of imines using peracid had emerged. Time to see how substituents respond to this mechanism.

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σ or π nucleophilic reactivity of imines? A mechanistic twist emerges.

Wednesday, September 28th, 2016
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The story so far. Imines react with a peracid to form either a nitrone (σ-nucleophile) or an oxaziridine (π-nucleophile).[1] The balance between the two is on an experimental knife-edge, being strongly influenced by substituents on the imine. Modelling these reactions using the “normal” mechanism for peracid oxidation did not reproduce this knife-edge, with ΔΔG (π-σ) 16.2 kcal/mol being rather too far from a fine balance.

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References

  1. D.R. Boyd, P.B. Coulter, N.D. Sharma, W. Jennings, and V.E. Wilson, "Normal, abnormal and pseudo-abnormal reaction pathways for the imine-peroxyacid reaction", Tetrahedron Letters, vol. 26, pp. 1673-1676, 1985. http://dx.doi.org/10.1016/S0040-4039(00)98582-4