General procedure for the synthesis of 4-aminoindan from 4-nitro-2,3-dihydro-1H-indene: 4-nitroindan (10 g, 61 mmol) was dissolved in 50 mL of ethanol in a 500 mL Parr shaker vessel. A 10% Pd/C (1 g) ethanol slurry was added. The mixture was subjected to a hydrogen atmosphere (50 psi) and reacted on a Parr oscillator for 1 h. The progress of the reaction was monitored by thin-layer chromatography (TLC, unfolding agent was a hexane solution of 20% ethyl acetate) to confirm that the feedstock was completely consumed. Upon completion of the reaction, the mixture was filtered twice through a diatomaceous earth pad and washed with a large amount of ethanol and filtered once more through filter paper. The ethanol was removed by evaporation under reduced pressure and the resulting crude product was purified by fast column chromatography on silica gel (eluent was a hexane solution of 10% ethyl acetate) to afford the target compound 4-aminoindan (8) as a viscous colored oil (7.04 g, 86% yield). Its 1H NMR (400 MHz, DMSO-d6) data were as follows: δ 1.95 (m, 2H), 2.61 (t, J = 7.3 Hz, 2H), 2.76 (t, J = 7.5 Hz, 2H), 4.77 (s, 2H), 6.36 (d, J = 7.8 Hz, 1H), 6.42 (d, J = 6.8 Hz, 1H), 6.80 (t, J = 7.6 Hz, 1H).
