14- and 17-Membered Macrocycles Containing Amide, Amino, and Carbamate Groups in The Monocyclic Skeleton: An Accidental Byproduct Obtained from a Residue after Separation

A 14-membered cyclic compound (3) containing
amide,
amino, and carbamate groups, which was serendipitously obtained in
the oily residue after the separation of 4-benzyl-1,4,7,10-tetraazacyldododecane-2,6-dione
(2a) and 4,16-dibenzyl-1,4,7,10,13,16,19,22-octaazacyclo-tetracosane-2,6,14,18-tetraone
(2b), is reported. The structure of 3 is
formally a CO2 insertion between positions 3 and 4 of the
12-membered ring in 2a. The CO2 insertion
was confirmed in the synthesis of diethyl 2,2′-(benzylazanediyl)diacetate
(1) by the reaction of benzylamine with ethyl bromoacetate
using K2CO3 as the base. In addition, the selective
synthesis of 3 and ethyl N-benzyl-N-((2-ethoxy-2-oxoethoxy)carbonyl)glycinate (5) and their kinetic behavior are reported. The reaction of 5 with triethylenetetramine afforded a 17-membered macrocycle
(7), which was
obtained in an 18% yield. Compounds 6 and 8 were prepared from 3 and 7 by introducing
benzyl groups to improve their solubility in organic solvents. Titration
experiments using 1H NMR showed that both 6 and 8 exhibit Li+ selectivity.