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4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone (110 mg, 0.4 mmol) in 2 ml of N,N-dimethylformamide and 110 μl of 15-crown-5 is treated with sodium hydride (20 mg, 0.5 mmol) under nitrogen at ambient temperature. After 3 hours, the mixture is cooled to 0° C. and treated with 2,3-difluorobenzyl bromide (166 mg, 0.8 mmol) in 2 ml of tetrahydrofuran. The resulting mixture is allowed to stir at ambient temperature for 6 hours. 100 ml of ethyl acetate is added, followed by 100 ml of ice cold water. After usual aqueous work up, the crude product is purified by flash column chromatography (ethyl acetate/hexane 2:1) to give 112 mg (70%) of 1-(2,3-difluorobenzyl)-4-(3-cyclopentyloxy-4-methoxyphenyl)-2-pyrrolidone: 1H NMR (300 MHz, CDCl3) δ 7.18-6.98 (m, 3H), 6.79 (d, J=8.1 Hz, 1H), 6.90 (d, J=8.1 Hz, 1H), 6.68 (s, 1H) 4.71-4.69 (m, 1H), 4.60 (s, 2H), 3.81 (s, 3H), 3.68 (t, J=9.0 Hz, 1H), 3.66-3.54 (m, 1H), 3.29 (dd, J=9.6, 7.2 Hz, 1H), 2.84 (dd, J=16.8, 9.0 Hz, 1H), 2.57 (dd, J=16.8, 8.4 Hz, 1H), 2.00-1.75 (b, 6H), 1.70-1.52 (b, 2H).

1. customAfter usual aqueous work up, the crude product is purified by flash column chromatography (ethyl acetate/hexane 2:1)