[Li+].[OH-].O.C([O:6][C:7](=[O:19])[C:8]1[CH:13]=[C:12]([C:14]#[N:15])[C:11]([NH2:16])=[C:10]([CH3:17])[C:9]=1[OH:18])C>C(O)C.O>[NH2:16][C:11]1[C:12]([C:14]#[N:15])=[CH:13][C:8]([C:7]([OH:19])=[O:6])=[C:9]([OH:18])[C:10]=1[CH3:17]To a solution of LiOH×H2O (8.4 g, 0.2 mol) in ethanol/water (1:1, 300 mL) was added compound 74 (22 g, 0.1 mol) at RT and the reaction mixture was refluxed at 80° C. for 4 h. The reaction mixture was concentrated under vacuum, the obtained residue was diluted with water (100 mL), washed with pet. ether/ethyl acetate (1:1, 2×200 mL). The aqueous layer was separated, acidified to pH=5 using 1.5N HCl and the obtained solid product was filtered off. The aqueous layer was further extracted with ethyl acetate (2×300 mL), dried and concentrated to give more product. The combined products was washed with 5% ethyl acetate in pet. ether to give the pure title compound (19 g, >95%).
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