(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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence