O.[OH-].[Li+].C([NH:11][C:12]1[CH:13]=[CH:14][C:15]2[O:20][CH2:19][CH2:18][N:17]([CH2:21][C:22]3[CH:23]=[C:24]([CH:29]=[CH:30][CH:31]=3)[C:25]([O:27][CH3:28])=[O:26])[C:16]=2[CH:32]=1)(=O)CCCCC.CO.O1CCCC1>O.C(O)(=O)C.C(OCC)(=O)C.C1(C)C=CC=CC=1>[NH2:11][C:12]1[CH:13]=[CH:14][C:15]2[O:20][CH2:19][CH2:18][N:17]([CH2:21][C:22]3[CH:23]=[C:24]([CH:29]=[CH:30][CH:31]=3)[C:25]([O:27][CH3:28])=[O:26])[C:16]=2[CH:32]=1Lithium hydroxide monohydrate (0.2 g.) in water (5 ml.) was added to a stirred solution of methyl 3-(6-hexanamido-2,3-dihydrobenz-1,4-oxazin-4-ylmethyl)benzoate (ca. 400 mg.) in 1:1 v/v methanol: tetrahydrofuran (10 ml.). When TLC (solvent system 80:20:2 v/v/v toluene:ethyl acetate:acetic acid) indicated complete disappearance of ester, the mixture was diluted with water, filtered to remove any solids, and carefully acidified with 1N hydrochloric acid. The precipitate was isolated by filtration and recrystallized from a mixture of methanol and water to give the title compound (0.176 g., 46% overall yield from amino ester (X)) as an off-white solid, m.p. 167°-171° C. (hemihydrate).
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