Yield: 78%

Reaction Conditions:

Stage #1:hydroquinone;L-Pyroglutamic acid with dmap in dichloromethane for 0.166667 h;
Stage #2: with dicyclohexyl-carbodiimide in dichloromethane at 20; for 14 h;

Steps:

4.2.2. General procedure for the synthesis of L-pyroglutamic acid ester (2a-2k) and L-pyroglutamines (3a-3j)
General procedure: To a round bottom flask with a stirring bar, L-pyroglutamic acid(10 mmol), phenol/aromatic amine (11 mmol) and DMAP (1 mmol) in dry CH2Cl2 (30 mL) was stirred for 10 min, followed by addition of DCC(11 mmol). The mixture was allowed to stir at room temperature overnight. The reaction was filtered through a coarse frit and the filtrate diluted with CH2Cl2 (50 mL), washed with brine (3×20 mL), dried over MgSO4, and concentrated to dryness. The crude mixture was purified using flash column chromatography (MeOH/ CH2Cl2=1/30) to give the pure products.

References:

Gang, Fang-li;Zhu, Feng;Li, Xiao-ting;Wei, Jie-lu;Wu, Wen-jun;Zhang, Ji-wen [Bioorganic and Medicinal Chemistry,2018,vol. 26,# 16,p. 4644 - 4649]