C([O:5][C:6](=[O:43])[CH2:7][C@@H:8]([CH2:28][C:29]1[N:30]=[C:31]([NH:34][C:35]([O:37][CH2:38][C:39]([Cl:42])([Cl:41])[Cl:40])=[O:36])[S:32][CH:33]=1)[C:9](N[C@@H](CC1CCCCC1)[C@@H](O)[C@@H](O)CC(C)C)=[O:10])(C)(C)C.[OH2:44].OO.O.[OH-].[Li+]>C1COCC1>[Cl:40][C:39]([Cl:42])([Cl:41])[CH2:38][O:37][C:35]([NH:34][C:31]1[S:32][CH:33]=[C:29]([CH2:28][C@H:8]([CH2:7][C:6]([OH:5])=[O:43])[C:9]([OH:10])=[O:44])[N:30]=1)=[O:36]The protected amido acid, 4-{[1(S)-(cyclohexylmethyl)-2(R),3(S)-dihydroxy-5 -methylhexyl]amino}-4-oxo-3-(R)-{{2-[(2,2,2-trichloroethoxy) carbonylamino]-4-thiazolyl}methyl}butanoic acid tert-butyl ester: A solution of the product of section (f) of this example (57.5 mg, 0.10 mmol) in THF (1.5 mL) and H2O (0.5 mL) was cooled to 0°. A 30% aqueous solution of H2O2 (91.3 μL, 0.80 mmol of H2 O2) and lithium hydroxide monohydrate (8.5 mg, 0.20 mmol) were added serially to the cooled solution. The mixture was stirred at 0° for 5 min and then at room temperature for 2.5 h. Excess H2O2 was quenched by the addition of a 1.5M aqueous solution of Na2SO3 (as judged by a KI stick indicator). The resulting mixture was diluted with H2O and washed with CH2Cl2 (3X). The aqueous layer was rendered acidic with 1N aqueous HCl and extracted with EtOAc (3X). The combined EtOAc extracts were washed with brine, dried (MgSO4) and concentrated to dryness to yield the desired monoprotected dicarboxylic acid, i.e. the 4-tert-butyl ester of 2(R)-{{2-[(2,2,2-trichloroethoxy) carbonylamino]-4-thiazolyl}-methyl}-butanedioic acid. The monoprotected dicarboxylic acid was used for the following coupling step without purification.
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