N-oxidation of 2-substituted pyridines and quinolines by dimethyldioxirane: Kinetics and steric effects

Article abstract of DOI:10.1515/HC.2007.13.1.25

The oxidation of 2-substituted pyridines and selected N-containing aromatic heterocycles by dimethyldioxirane (1) produced the corresponding N-oxides as the sole products, quantitatively in most cases. The second order rate constants for N-oxidation by 1 in dried acetone at 23°C were determined for a series of 2-substituted pyridines 2-10, quinolines 11-14 and isoquinolines 15,16. An excellent correlation of log k₂ with Taft (σ*) constants was obtained for 2-substituted pyridines (R = Me, Et, Prⁿ, Pr ⁱ, 3-pentyl) with the exception of the data for 2-f-butylpyridine. The results for the substituted quinolines and isoquinolines followed the same trends observed with the pyridines. Steric effects due to 2-substitution and periinteractions can substantially reduce reactivity. The results provide insights into the geometrical requirements for N-oxidation by dimethyldioxirane.

Full text of DOI:10.1515/HC.2007.13.1.25

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Brought to you by | University of California
Authenticated
Download Date | 6/6/15 12:11 PM

Brought to you by | University of California
Authenticated
Download Date | 6/6/15 12:11 PM

Brought to you by | University of California
Authenticated
Download Date | 6/6/15 12:11 PM