A mixture of 1 g (3.1 mmol) 4-(3-amino-4-nitro-phenyl)-piperazine-1-carboxylic acid tert-butyl ester, 0.793 g (4.65 mmol) phenoxyacetyl chloride and 2.2 g (21.7 mmol) triethylamine in 20 ml THF was stirred at room temperature for 30 min. The mixture was evaporated and 100 ml DCM were added. The organic phase was washed with 2×50 ml 0.1 M Na2CO3 aq. The combined aqueous phase was extracted with 2×100 ml DCM. The combined organic phases were dried with MgSO4 and evaporated to dryness. The residue was purified over silica eluting with ethyl acetate/hexane 1/1 to yield 1.15 g (81%) of the title compound as yellow solid. MS(ISP): 455.3 (M−H)−.
