[C:1](Cl)(Cl)=[O:2].[NH2:5][C@H:6]([C:10]([OH:12])=[O:11])[CH:7]([CH3:9])[CH3:8]>C1(C)C=CC=CC=1.C1COCC1>[CH:7]([C@H:6]1[C:10](=[O:11])[O:12][C:1](=[O:2])[NH:5]1)([CH3:9])[CH3:8]30.4 ml (57.47 mmol, 1.08 eq.) of a 20% solution of phosgene in toluene were added slowly at r.t. to a stirred solution of 6.26 g (53.44 mmol) L-valine (81a) in 63 ml dry THF. After the complete addition the mixture was heated at 55° C. for 4 h. Then a stream of nitrogen was bubbled through the solution and passed after that through a 1M aq. NaOH-solution for 20 min. before the solvent was evaporated. Recrystallization of the obtained residue from PE/Ether (2:1) yielded 3.62 g (25.29 mmol, 47.32%) (S)-4-Isopropyl-oxazolidine-2,5-dione (86) as a white solid.
Wird geladen…
