Orientation in Base-Promoted Dehydrohalogenation of N-(Chlorobenzyl)-n-butylamine

Although the mechanisms of olefin formation by basepromoted dehydrohalogenation have been extensively investigated,^{3, 4} the removal of hydrogen halide across C-N bonds has received little attention. The only kinetic studies of imine-forming dehydrohalogenation involve the reactions of alkyldifluoroamines, RCH₂NF₂, in water-diglyme at 25-75 °C reported by Braumann and Hill.^{5, 6} In contrast to the strongly basic conditions required for alkene formation by dehydrofluorination of closely related 1, 1-difluoro-2-arylethanes,⁷ water was a sufficiently strong base to induce eliminations from the alkyldifluoroamines. These observations underscore the marked facility of carbon-heteroatom multiple bond forming eliminations when compared with analogous processes leading to alkenes or alkynes.