Several preparations of DEPA (2b) have been reported. One route employed the direct acylation of N-ethylethylenedihe with p-nitrobenzoyl chloride followed by reduction of the nitro group: In our hands, this acylation was not selective, leading to a complex mixture which was difficult to purify. The same group reported a second route to 2b which entailed acylation of N-ethylethylenediamine with N-Cbz-protected p-aminobenzoic acid NHS ...
