[ClH:1].C(OC([N:9]1[CH2:14][CH2:13][N:12]([C:15]2[C:20]([CH3:21])=[CH:19][C:18]([N+:22]([O-:24])=[O:23])=[CH:17][N:16]=2)[CH2:11][CH2:10]1)=O)(C)(C)C>C(Cl)Cl.O1CCOCC1>[ClH:1].[CH3:21][C:20]1[C:15]([N:12]2[CH2:11][CH2:10][NH:9][CH2:14][CH2:13]2)=[N:16][CH:17]=[C:18]([N+:22]([O-:24])=[O:23])[CH:19]=1Add a solution of HCl 4M in dioxane (4 equiv) to a solution of 4-(3-Methyl-5-nitro-pyridin-2-yl)-piperazine-1-carboxylic acid tert-butyl ester (7.77 g, 24.13 mmol) in DCM (73 mL). Stir mixture at room temperature overnight. Add 2 more equiv of the HCl in dioxane solution. After no starting material is detected by LCMS, filter solid and dry under reduced pressure to obtain 6.91 g of 1-(3-methyl-5-nitro-pyridin-2-yl)-piperazine hydrochloride as a yellowish solid (97% yield). ES+(m/z): 259 [M+1].
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