A mixture of 6-chloro-2-methylamino-3-nitrobenzonitrile (200 mg, 0.95 mmol) (Example 4), ethyl 2-oxocyclopentanecarboxylate (177 mg, 1.13 mmol) and K2CO3 (287 mg, 2.07 mmol) in DMF (5 mL) was stirred at room temperature for 60 h. The mixture was diluted with sat. NH4Cl solution and extracted with ether. The ethereal layer was washed with water and brine, dried (Na2SO4), filtered and concentrated. The residue was purified by chromatography on silica (hexanes: EtOAc=3:1) to give ethyl 1-(2-cyano-3-methylamino-4-nitrophenyl)-2-oxo-cyclopentanecarboxylate (127 mg, 40%) as a yellow solid.
