A solution of N,N′-dimethylethylenediamine (1.72 g) in toluene (15 mL) was added to a mixture of methyl 3-bromo-6-(2,2-dimethylpropionylamino)-2-nitro-benzoate (Intermediate 58, 1.72 g), pyrrolidin-2-one (0.489 g), copper(I) iodide (0.091 g) and potassium carbonate (1.32 g) and the mixture was stirred and heated under nitrogen at 110° C. for 5 hours. After cooling, the mixture was diluted with water and ethyl acetate and the organic phase was dried (Na2SO4) and filtered. The filtrate was concentrated in vacuo and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and cyclohexane with a gradient of 10-80% to give methyl 6-(2,2-dimethylpropionylamino)-2-nitro-3-(2-oxopyrrolidin-1-yl)-benzoate (0.310 g) as an off-white solid.
