Reactions of N-Chlorobenzylmethylamines with Secondary Amines in Acetonitrile. Effect of Base Strength upon the Imine-Forming Transition State

Article abstract of DOI:10.1021/jo00358a030

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, k_H/k_D = 8.8, ρ = 0.96, ΔH(excit.) = 7.6 kcal/mol, and ΔS(excit.) = -45.1 eu were determined.The transition state structure is assessed as being highly symmetrical with similar extents of C_β-H and N_α-Cl bond cleavage, little carbanionic character, and significant ? bond formation.The k_H/k_D and ρ 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.