L-Pyroglutamic Acid → tert-Butyl 5-oxo-L-prolinate

Participants

Reaction Steps

Step (a) Aqueous perchloric acid (70%, 5 mL) was added to a solution of (S)-5-oxopyrrolidine-2-carboxylic acid (20 g, 154.9 mmol) in tert-butyl acetate (260 mL) at ambient temperature. The mixture was stirred at ambient temperature for 18 hrs in a 500 mL round bottom flask sealed with a rubber septum and then poured carefully into sat. sodium bicarbonate (200 mL). The mixture was extracted with ethyl acetate (2×200 mL) and the combined extract was dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product solidified under high vacuum. The solid was treated with a 10:1 hexanes/diethyl ether mixture. The solids were collect by filtration and dried to give (S)-tert-butyl 5-oxopyrrolidine-2-carboxylate (21.65 g, 116.9 mmol, 75.5%), clean as a white solid.

Provenance & Evidence