Dimethylamine, hydrochloride → Benzenamine, 2-chloro-N,N-dimethyl-4-nitro-

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A solution of 3-chloro-4-fluoronitrobenzene (3.0 g, 17.1 mmol), dimethylamine hydrochloride (1.53 g, 18.8 mmol) and K2CO3 (4.96 g, 35.9 mmol) in Me2SO (20 mL) was heated in a sealed tube at 105° C. for 18 h. On cooling the reaction mixture was poured into water (200 mL) and extracted with EtOAc. The combined organics were washed with brine, dried on MgSO4, filtered, and evaporated to give 3.47 g of 3-chloro-4-(dimethylamino) nitrobenzene as a yellow solid. An aliquot of this (3.4 g, 16.95 mmol) was dissolved in 20 mL of EtOH/AcOH (1:1, v/v) with warming. Iron powder (−325 mesh, 9.5 g, 170 mmol) was added in small portions. The mixture was then heated on a steam bath for 30 min. The mixture was cooled, filtered through a pad of celite and the filtrate was evaporated to give 3.33 g of 3-chloro-4-(dimethylamino)aniline as a dark solid. A solution of this compound in EtOH (10 mL) was treated with HNO3 (69% aq, 2.6 mL, 40.6 mmol) dropwise, followed by cyanamide (50% solution in water, 5.3 mL, 67.78 mmol). After heating for 18 h at reflux the reaction mixture was cooled to room temperature, poured into Et2O (100 ml) and basified with NaOH solution (2 N, 100 mL). The ethereal layer was separated. The aqueous phase was extracted with Et2O. The combined organic phases were washed with brine, dried on MgSO4, filtered, and evaporated to give a black oil, which solidified on standing to afford 1.6 g of the title compound. RP-HPLC: tR=12.7 min (10-70% MeCN in 0.1% aq CF3COOH over 20 min, 1 mL/min, purity>95%). 1H-NMR (CD3OD) δ: 2.68 (s, 3H, CH3), 2.70 (s, 3H, CH3), 2.75 (s, 6H, CH3), 7.05 (d, 1H, J=5.1 Hz), 7.15 (d, 1H, J=8.8 Hz, pyrimidinyl-H), 7.49 (dd, 1H, J=8.8, 2.4 Hz, Ph-H), 7.94 (d, 1H, J=2.4 Hz, Ph-H), 8.43 (d, 1H, J=5.4 Hz, pyrimidinyl-H). MS (ESI+) m/z=393 [M+Na] (C17H18N6O2S requires 370.4).

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