A method of preparing a N-acyl-N,N′,N′-alkylenediamine trialkanoic acid ester comprising contacting a cyclic amidine with an ester of a haloalkanoic acid is provided. In some embodiments, the method involves preparing a N-acyl-N,N′,N′-ethylenediamine trialkanoic acid ester by contacting a 2-alkyl imidazoline with the ester of haloalkanoic acid. In some embodiments, the N-acyl-N,N′,N′-alkylenediamine trialkanoic acid ester is a synthetic intermediate in the preparation of a N-acyl-N,N′,N′-alkylenediamine trialkanoic acid or a salt thereof. In some embodiments, the method provides novel N-acyl-N,N′,N′-alkylenediamine trialkanoic acids and/or esters, which can be used, for example, as chelating agents.