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

Participants

Reaction Steps

30.0 g of L-pyroglutamic acid 133 (232 mmol) was suspended in 500 ml of tert-butyl acetate and added with 12 ml of 60% perchloric acid. After stirring for 15 h at RT, the resulting clear solution was cooled to 0° C. and adjusted to a pH value of 4-5 by adding 30.0 g of solid NaHCO3. After removing the solid by filtration, the filtrate was concentrated to dryness, thereby obtaining 25.4 g (136 mmol, 58%) of the tert-butyl ester 206 as a white solid that was reacted without further purification. An analytical sample was obtained by column chromatography over silica gel (eluant: EE).

Provenance & Evidence