(a) Synthesis of N,N-dimethyl-o-phenylenediamine. N,N-dimethyl-2-nitroaniline (1.00 g, 6.02 mmol), ethanol (22 mL) and ethyl acetate (60 mL) were added to a hydrogenation reaction flask. To the resulting orange solution was added 5% palladium/carbon catalyst (0.67 g), followed by triple degassing of the black suspension and charging with hydrogen (50 psi). After shaking the reaction mixture for 5 h at room temperature, it was filtered through a diatomaceous earth pad (2 in. x 1.5 in.), the filter cake was washed with ethyl acetate (50 mL), and the filtrate was concentrated to obtain an orange residue. Purification by fast column chromatography (silica gel, eluent ethyl acetate:hexane = 1:15) afforded 0.73 g (89% yield) of N,N-dimethyl-o-phenylenediamine as an orange oil: 1H-NMR (CDCl3) δ 7.00 (dd, J = 7.8 and 1.5 Hz, 1H), 6.90 (td, J = 7.6 and 1.5 Hz, 1H). 6.76-6.68 (m, 2H), 3.93 (br s, 2H), 2.65 (s, 6H). (b) Synthesis of N-(2-dimethylaminophenyl)-9-oxo-9H-fluorene-1-carboxamide. Referring to the method of Example 9, the reaction of N,N-dimethylphthalimide (0.281 g, 2.06 mmol) with 9-oxo-9H-fluorene-1-carbamoyl chloride (0.500 g, 2.06 mmol) afforded 0.356 g (50% yield) of the target product as a brown solid: melting point 152-155°C; 1H-NMR (CDCl3) δ 10.77 (br s, 1H), 8.42-8.40 (m, 1H), 8.06 (d, J=8.2Hz, 1H), 7.72-7.54 (m, 5H), 7.36-7.33 (m, 1H), 7.18-7.12 (m, 3H), 2.70 (s, 6H).
