“…Earlier, we reported − the chemoselective S- and N-alkylation of the model compound 4-methyl-1-thioxo-1,2,4,5-tetrahydro[1,2,4]triazolo[4,3- a ]quinazolin-5-one with different electrophiles. These results were supported by quantum-chemical calculations. − We also applied these findings to the structure modification of a number of heterocyclic thioamides, quinazolines, tetrazoles, triazoloquinazolines, − , and triazoloquinoxalines . Nonproteinogenic amino acids are major components in a number of drugs including β-lactam antibiotics and antiviral drugs .…”