(S)-4-carbobenzyloxy-1-(4,5-dichloro-2-nitrophenyl)-piperazine-2-carboxylic acid → (S)-8,9-Dichloro-2,3,4,4a-Tetrahydro-1H-Pyrazino[1,2-a]Quinoxalin-5(6H)-One

HRID 1016381Notes

Reaction equation

C([N:11]1[CH2:16][CH2:15][N:14]([C:17]2[CH:22]=[C:21]([Cl:23])[C:20]([Cl:24])=[CH:19][C:18]=2[N+:25]([O-])=O)[C@H:13]([C:28]([OH:30])=O)[CH2:12]1)(OCC1C=CC=CC=1)=O>C(O)(=O)C.[Fe]>[Cl:24][C:20]1[CH:19]=[C:18]2[C:17](=[CH:22][C:21]=1[Cl:23])[N:14]1[CH2:15][CH2:16][NH:11][CH2:12][C@H:13]1[C:28](=[O:30])[NH:25]2

Participants

Conditions

Temperature: 60 °C

Procedure

To a solution of 1.5 g (S)-4-carbobenzyloxy-1-(4,5-dichloro-2-nitrophenyl)-piperazine-2-carboxylic acid in 40 mL of acetic acid is added 1.2 g of iron powder. With good stirring, the mixture is heated at 60° C. for 2 hours, then concentrated under reduced pressure (1-2 mm, <40° C.) to a gray-black residue. This material was slurried with 100 mL of ethyl acetate (2×). The combined ethyl acetate filtrates are washed with 100 mL of 1 N HCl, 200 mL of water (2×), 100 mL of brine and dried over MgSO4. Filtration and concentration of the solvent gave a semi-solid material that is crystallized from hexane to afford 1.08 g (80.6%) of title compound as a white solid, mp 174-6° C.

Workup

concentrationconcentrated under reduced pressure (1-2 mm, <40° C.) to a gray-black residue
washThe combined ethyl acetate filtrates are washed with 100 mL of 1 N HCl, 200 mL of water (2×), 100 mL of brine
dry with materialdried over MgSO4
filtrationFiltration and concentration of the solvent
customgave a semi-solid material that
customis crystallized from hexane

Sources & evidence

ORD record: ord-a5d7f04dc4674b0198854c1f04739ed4
Source dataset: uspto-grants-2002_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06476032B2

Reaction notes

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