Reactions of N-chlorobenzylmethylamines 1 with R2NH in MeCN have been investigated kinetically. Eliminations from 1 were quantitative and regiospecific, producing only benzylidenemethylamines. For the elimination reaction of 1 with Bu2NH, kH/kD = 8.8, p = 0.96, ΔH* = 7.6 kcal/mol, and ΔS#= -45.1 eu were determined. The transition state structure is assessed as being highly symmetrical with similar extents of Cβ-H and Nα-C1 bond cleavage, little carbanionic character, and significant π bond formation. The kH/kD and p values first increase and then decrease with enhancing amine base strength. Comparison of these results with those for related olefin-forming eliminations provides insight into the transition state differences between imine- and olefin-forming eliminations.
ASJC Scopus subject areas
- Organic Chemistry