Methyl 4-[(2-chloroethyl)amino]-3,5-dinitrobenzoate → Methyl 8-nitro-1,2,3,4-tetrahydro-6-quinoxalinecarboxylate

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Reaction Steps

To a solution of crude methyl 4-[(2-chloroethyl)amino]-3,5-dinitrobenzoate (D208) (9 g, 19.2 mmol, 1 equiv) in MeOH (75 ml) and cyclohexene (150 ml) was added 10% palladium on charcoal (50% wet, 4.5 g, 25% w/w) and the resulting mixture was refluxed for 3 h then cooled to room temperature. The catalyst was filtered off through a pad of celite and most of the solvent was removed in vacuo. The residue was partitioned between AcOEt and a 2N aqueous HCl solution and the two layers were separated. The aqueous phase was extracted twice with AcOEt and the combined organic layers were washed with a saturated aqueous NaHCO3 solution, dried over MgSO4 and concentrated in vacuo. Purification of the residue by flash chromatography on silica gel (iso-hexane/AcOEt: 1/1) gave methyl 8-nitro-1,2,3,4-tetrahydro-6-quinoxalinecarboxylate (D209) (1.5 g, 34%) as a red solid. [M−H]−=236.2, RT=2.65 min.

Provenance & Evidence