Cl.[NH:2]1[CH2:7][CH2:6][CH2:5][CH2:4][CH:3]1[CH2:8][CH2:9]CC(O)=O.C([O-])([O-])=O.[K+].[K+].[C:20]([O:24]C(OC(OC(C)(C)C)=O)=O)(C)(C)[CH3:21]>C(OC(=O)C)C.O.O1CCOCC1>[CH2:7]([NH:2][CH:20]([OH:24])[CH3:21])[C:6]1[CH:5]=[CH:4][CH:3]=[CH:8][CH:9]=1
4-Piperidin-2-ylbutanoic acid Hydrochloride (10.0 g, 48.3 mmol), and K2CO3 (26.6 g, 193.1 mmol) was dissolved in dest. water (70 ml) and Dioxane (124 ml). The reaction mixture was cooled to 0° C. and at this temperature Di-tert-butyldicarbonate (11.4 g, 53.1 mmol) was added slowly. The reaction mixture was stirred for 24 h at room temperature. After completion of the reaction water and Ethylacetate were added, the two phases were separated. The aqueous Phase was extracted once with Ethylacetate. Afterwards the aqueous Phase was triturated with 2 M HCL (aqueous) to reach pH=2. At this pH the aqueous phase was extracted 4× with Dichloromethane. The combined organic layers were dried over Magnesium sulfate, filtered out and evaporated to complete dryness to give (2) (13.13 g, 100%).
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