[CH:1]([N:4]1[CH2:9][CH2:8][N:7]([C:10]2[CH:15]=[CH:14][C:13]([N+:16]([O-])=O)=[CH:12][N:11]=2)[CH2:6][CH2:5]1)([CH3:3])[CH3:2].O.O.[Sn](Cl)Cl.Cl>CO>[CH:1]([N:4]1[CH2:5][CH2:6][N:7]([C:10]2[N:11]=[CH:12][C:13]([NH2:16])=[CH:14][CH:15]=2)[CH2:8][CH2:9]1)([CH3:3])[CH3:2]1-Isopropyl-4-(5-nitro-pyridin-2-yl)-piperazine (0.9 g, 3.6 mmol) is dissolved in MeOH (20 mL) and tin (II) dichloride dihydrate (4 g, 18 mmol) is added. The mixture is cooled using a water bath and conc. HCl is added (4 mL). The reaction is stirred at room temperature overnight. After removing the methanol, the resultant light yellow solution is basified using conc. NaOH (pH 11) and a white precipitate is formed. The solid is collected by filtration and the water is extracted with diethyl ether (5×). The organic layers are combined, dried over MgSO4, filtered, concentrated under vacuum to afford an orange oil which crystallizes on standing to afford an orange solid (0.68 g, 86%).
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