To a 1-liter 3-necked round-bottomed flask equipped with an overhead stirrer, temperature control and an addition funnel was added dibenzyl-(4-iodo-2,5-dimethylphenyl)amine (15 g, 35 mmol). Toluene (300 mL) was added and the resulting mixture was stirred for about 15 minutes. The reaction flask was purged with dry nitrogen and cooled to about −20° C. and 1.6 M n-butyllithium in hexanes (33 mL, 53 mmol) was added dropwise via the addition funnel. During the addition, the internal temperature of the reaction mixture was maintained below −10° C. When the addition was complete, the resulting mixture was stirred at about −15° C. for 15 minutes. N,N-Dimethylformamide (10 mL, 129 mmol) was then added dropwise while maintaining the internal reaction temperature below 0° C. The resulting mixture was then stirred at −20° C. to 0° C. for about 1 hour. Aqueous 1 M hydrochloric acid (200 mL) was then added over a 5 minute period and the resulting mixture was stirred for 15 minutes. The layers were then separated and the organic layer was washed with dilute brine (100 mL). The organic layer was then dried over anhydrous sodium sulfate, filtered and the solvent removed under reduced pressure to provide 4-dibenzylamino-2,5-dimethylbenzaldehyde hydrochloride (11.5 g, 90% yield, 95% purity) as thick oil that solidified upon standing. The product contained about 3 to 5% of the des-iodo by-product. 1H NMR (300 MHz, CDCl3) δ 2.42 (s, 3H), 2.50 (s, 3H), 4.25 (s, 4H), 6.82 (s, 1H), 7.10-7.30 (m, 10H), 7.62 (s, 1H), 10.15 (s, 1H); MS [M+H+] found 330.3.
