[C:1]1([CH2:7][O:8][C:9]([NH:11][CH2:12][C@@H:13]2[CH2:18][CH2:17][CH2:16][N:15](C(OC(C)(C)C)=O)[CH2:14]2)=[O:10])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1.Cl.O1CCOCC1>C(Cl)Cl.O>[NH:15]1[CH2:16][CH2:17][CH2:18][C@@H:13]([CH2:12][NH:11][C:9](=[O:10])[O:8][CH2:7][C:1]2[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=2)[CH2:14]11,1-Dimethylethyl (3S)-3-[({[(phenylmethyl)oxy]carbonyl}amino)methyl]-1-piperidinecarboxylate (˜9.3 mmol) was dissolved in DCM (25 mL) and treated with a 4M HCl solution in 1,4-dioxane (24 mL, 96 mmol). The reaction was stirred at room temperature for 3 h, at which time LC/MS indicated that all starting material was consumed. The reaction was concentrated in vacuo to give a thick gum. This material was dissolved in water and extracted with ethyl acetate. The aqueous phase was separated and treated with solid Na2CO3 to bring the pH to ˜10. The product was then extracted into CHCl3 (3×) and the combined organic phases were dried (Na2SO4) and concentrated to yield the desired product as an orange oil (2.3 g, 100% for two steps).
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