Transition-State Structures of Base-Promoted, Imine-Forming Eliminations from N-Benzyl-O-(arylsulfonyl)hydroxylamines

Article abstract of DOI:10.1021/ja00372a014

Eliminations in XC6H4CH2NHOSO2C6H4Y promoted by amine bases were examined in 2.25 M H2O in THF-EtOAc (3:1) and methanol.Transition-state parameters in methanol were found to be ρ = 0.11, k_H/k_D = 1.2, for the benzylic group and ρ = 1.65 for the leaving group.These data indicate that the polar solvent methanol causes an E1-like transition state in this elimination.Broensted parameters were determined for both solvent and found to be α = 0.3 and β = 2.32 for the former and α = 0.1 and β = 2.65 for methanol.These parameters can be used to map the transition-state structure in a More-O'Ferral-Jencks diagram.Values of β_1g for a variety of reactions are found to be a useful gauge of reaction type and leaving group loss in the transition state.