The revisited synthesis of tert-butyl pyroglutamate derivatives

Reaction conditions for the substitution of bromine in tert-butyl bromide by pyroglutamic anion were discovered. This green reaction gives a quantitative yield of the tert-butyl pyroglutamate. It was also demonstrated that non toxic N-methylimidazole and tert-butanol can pleasantly replace the problematic toxic 4-dimethylaminopyridine (DMAP) and dichloromethane often utilized for the N-carbamoylation of this lactam.