Reactions of Aryl Phenylacetates with Secondary Amines in MeCN. Structure-Reactivity Relationship in the Ketene-Forming Eliminations and Concurrent E2 and E1cb Mechanisms

摘要

Elimination reactions of aryl esters of arylacetic acids 1 and 2 promoted by R_2NH in MeCN have been investigated kinetically. The reactions are second-order and exhibit β=0.44-0.84, ∣β_1g∣=0.41-0.50, and ρH= 2.0-3.6. Bronsted β and ∣β_1g∣decrease with the electron-withdrawing ability of the β-aryl substituen. Hammett ρH values remain nearly the same, but the ∣β_1g∣value increases as the base strength becomes weaker.