[NH2:1][C@@H:2]1[CH2:11][CH2:10][C:5]2([O:9][CH2:8][CH2:7][O:6]2)[CH2:4][C@H:3]1[C:12]([O:14][CH2:15][CH3:16])=[O:13].C(=O)([O-])[O-].[K+].[K+].[CH2:23](Br)[CH2:24][CH3:25].O>CN(C=O)C>[CH2:23]([NH:1][C@@H:2]1[CH2:11][CH2:10][C:5]2([O:9][CH2:8][CH2:7][O:6]2)[CH2:4][C@H:3]1[C:12]([O:14][CH2:15][CH3:16])=[O:13])[CH2:24][CH3:25]Ethyl 8-amino-trans-1,4-dioxaspiro[4.5]decane-7-carboxylate (118.0 g, 0.52 mole) was dissolved in DMF (1 l) and potassium carbonate (107 g, 0.77 mole) and propyl bromide (158.4 g, 1.3 mole) were added. The mixture was heated to 50° C. for three hours, then poured into water, and the hydrogen ion concentration was adjusted to pH 10. The product was extracted with methylene chloride, dried and evaporated to give 136 g of a dark orange oil.
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