Hydrochloric Acid → Ethyl L-threoninate

A current of dry HCl was passed through a suspension of L-threonine (35.0 g, 0.29 mol) in absolute ethanol (350 ml), with shaking, until a clear solution formed. The solution then refluxed for 30 minutes, and was evaporated to dryness under reduced pressure, and the oily residue was taken up in absolute ethanol (175 mL) and, again, taken to dryness under reduced pressure. The oily residue was then treated with a saturated solution of ammonia in chloroform. The ammonium chloride was filtered off and the filtrate was taken to dryness at 0° C. under reduced pressure. A yellow solid was isolated (36.2 g. 85%); [α]29Na+0.82° (c 5.0, EtOH). Lit.12 [α]29D+0.95° (C 5.0 EtOH); m.p. 51-53° C. (Lit12 52-54° C.); 1H NMR (200 MHz, CDCl3 w/TMS) δ 4.82 (1H.m), 4.40 (1H,d), 4.05 (2H,q), 1.62 (3H,d), 1.21 (3H;t); FABMS 148.2 (M+H); HRFABMS Calcd for C6H14NO3 (M+H) 148-0974, found 148.0972.

1. customformed
2. temperatureThe solution then refluxed for 30 minutes
3. customwas evaporated to dryness under reduced pressure
4. additionThe oily residue was then treated with a saturated solution of ammonia in chloroform
5. filtrationThe ammonium chloride was filtered off
6. customwas taken to dryness at 0° C. under reduced pressure
7. customA yellow solid was isolated (36.2 g. 85%)
8. customm.p. 51-53° C. (Lit12 52-54° C.)

ORD record

ord-e3eac10ba62e434e94b7a7acb8082f58

Source dataset

uspto-grants-2002_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06380156B1