Synthesis of New Purine Derivatives Containing α- and ω-Amino Acid Fragments

Stereochemical aspects in the synthesis of novel N-(purin-6-yl)dipeptides as potential antimycobacterial agents

“…We were surprised to observe double sets of signals in the 1 H and 13 C NMR spectra of products 3a–c (according to 1 H NMR, in a 6:4 ratio). It should be noted that when conducting coupling of achiral carboxy component ( N -(purin-6-yl)glycine and N -(purin-6-yl)-beta-alanine) to chiral amino component (methyl ( S )-tyrosinate, methyl ( S )-serinate, or dimethyl ( S )-glutamate) in the presence of a DCC–HOBt mixture, we did not observe any racemization at the chiral centers of the target pyrinyl dipeptides (Musiyak et al 2019 ). So, we can conclude that in the present case racemization occurs at the chiral center of the carboxy component, thus leading to the formation of a mixture of ( S,S )- and ( R,S )-diastereomers.…”

“…It has been found that the analogs of compounds ( S )- 1a,b in which the ( S )-glutamic acid fragment is replaced by residues of other α-amino acids, as well as the analogs in which the glycine fragment is replaced by residues of various ω-amino acids, do not exhibit substantial antimycobacterial activity (Musiyak et al 2019 ). The purpose of this work was to obtain the analogs of compounds ( S )- 1a,b containing fragments of natural α-amino acids instead of glycine moiety.…”