[Si]([O:8][CH:9]([C:19]1[CH:20]=[CH:21][C:22]([C:25](=O)[CH2:26][CH2:27][C:28](=O)[CH:29]([C:36]2[CH:41]=[CH:40][C:39]([S:42][CH3:43])=[CH:38][N:37]=2)[CH2:30][CH:31]2[CH2:35][CH2:34][CH2:33][CH2:32]2)=[N:23][CH:24]=1)[CH2:10][O:11][Si](C(C)(C)C)(C)C)(C(C)(C)C)(C)C.C([O-])(=O)C.[NH4+:50].C(=O)([O-])O.[Na+]>C(O)(=O)C.C(OCC)(=O)C>[CH:31]1([CH2:30][CH:29]([C:28]2[NH:50][C:25]([C:22]3[N:23]=[CH:24][C:19]([CH:9]([OH:8])[CH2:10][OH:11])=[CH:20][CH:21]=3)=[CH:26][CH:27]=2)[C:36]2[CH:41]=[CH:40][C:39]([S:42][CH3:43])=[CH:38][N:37]=2)[CH2:35][CH2:34][CH2:33][CH2:32]1To a solution of 1-[5-(1,2-bis{[tert-butyl(dimethyl)silyl]oxy}ethyl)pyridin-2-yl]-6-cyclopentyl-5-[5-(methylsulfanyl)pyridin-2-yl]hexane-1,4-dione (682 mg) in acetic acid (7 mL) was added ammonium acetate (1.26 g), and the mixture was stirred at 110° C. for 45 min. After cooling to room temperature, the mixture was neutralized with saturated aqueous sodium hydrogen carbonate solution. The reaction mixture was diluted with ethyl acetate and washed with water. The ethyl acetate layer was dried (MgSO4) and concentrated. To a solution of the obtained residue in tetrahydrofuran (4 mL) was added tetrabutylammonium fluoride (1M tetrahydrofuran solution, 8.16 mL), and the mixture was stirred at room temperature for 1.5 hr. The reaction mixture was diluted with ethyl acetate, and washed with saturated brine. The ethyl acetate layer was dried (MgSO4) and concentrated. The residue was subjected to silica gel column chromatography, and the title compound (230 mg, yield 53%) was obtained as a colorless amorphous solid from a fraction eluted with ethyl acetate-hexane (99:1, volume ratio). MS: 424 (MH+).
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