tert-butyl groups on lactams or acids in the pyroglutamic series have been revisited in a green perspective. Particularly, reaction conditions allowing a quantitative yield in substitution of bromine in tert-butyl bromide were discovered for the first time, allowing the synthesis of tert-butyl pyroglutamate 4. This synthesis of tert-butyl ester by nucleophilic substitution, realized without using concentrated
The conjugation of methotrexate (Mtx) with a siderophore to construct “Trojan horse” antibacterial conjugates is reported. The most potent conjugate exhibited over 1000-fold improved activity against Gram-positive Streptococcus pneumoniae and Gram-negative Yersinia enterocolitica compared with Mtx, while possessing 2313-fold reduced human cytotoxicity, resulting in 2.08×106-fold improvements in the