Hydrochloric Acid → Diisopropyl Ether

Participants

Reaction Steps

To a solution of 1.584 g (7 mmol) of Pry-Pro-OH (III) dissolved in 20 ml of anhydrous tetrahydrofuran, 0.79 ml (7 mmol) of N-methylmorpholine and 0.69 ml (7 mmol) of ethylchloroformate were successively added at -12° C. After stirring for 2 minutes, a cold solution of 2.596 g (7 mmol) of HCl.H-Trp-Met-NH2 (II) and 0.79 ml (7 mmol) of N-methylmorpholine in 20 ml of dimethylformamide was added. The reaction mixture was stirred for 1 h at -12° C. and for 2 h at 0°-15° C., then filtered to remove salts and evaporated in vacuo. The crude product was purified by column chromatography on silica gel (Merck) 0.040-0.063 mm with an eluent of chloroform:methanol:water of 87:13:1 by volume. A 2.545 g (67% yield) amount of IV was obtained from diisopropyl ether: m.p. 207°-209° C., [α]D23 = -95.3° (c=1 MeOH); RfC 0.43. Amino acid ratio: Glu 1.00; Pro 0.98; Met 1.00.

Provenance & Evidence