Potassium Carbonate → benzyl (9aS)-4-oxohexahydropyrazino[2,1-c][1,4]oxazine-8(1H)-carboxylate
Reaction equation
Br[CH2:2][C:3]([N:5]1[CH2:10][CH2:9][N:8]([C:11]([O:13][CH2:14][C:15]2[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=2)=[O:12])[CH2:7][C@H:6]1[CH2:21][OH:22])=[O:4].C(=O)([O-])[O-].[K+].[K+]>C1(C)C=CC=CC=1>[O:4]=[C:3]1[CH2:2][O:22][CH2:21][C@@H:6]2[CH2:7][N:8]([C:11]([O:13][CH2:14][C:15]3[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=3)=[O:12])[CH2:9][CH2:10][N:5]12Participants
4
Procedure
Benzyl (3S)-4-(bromoacetyl)-3-(hydroxymethyl)piperazine-1-carboxylate (1.1 g, 2.9 mmol was dissolved in toluene (25 mL) and to the resultant solution was added potassium carbonate (4.0 g, 28.8 mmol). The mixture was heated to reflux overnight, cooled to RT and then the solids were filtered off. The solvent was removed by evaporation and the product was purified by chromatography on silica gel (methanol-methylene chloride 1% to 10%). There was obtained 0.19 g (23%) of benzyl (9aS)-4-oxohexahydropyrazino[2,1-c][1,4]oxazine-8(1H)-carboxylate as a colorless oil. 1H NMR (500 MHz, CDCl3): 2.6-3.0 (m, 3H), 3.4-3.6 (m, 2H), 4.0 (d, 1H), 4.1-4.3 (m, 4H), 4.5 (d, 1H), 5.1 (s, 2H), 7.2-7.4 (m, 5H).