反应详情

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 H2O2) 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 (3×). The aqueous layer was rendered acidic with 1N aqueous HCl and extracted with EtOAc (3×). 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.

1. customwas cooled to 0°
2. waitat room temperature for 2.5 h
3. customExcess H2O2 was quenched by the addition of a 1.5M aqueous solution of Na2SO3 (
4. additionThe resulting mixture was diluted with H2O
5. washwashed with CH2Cl2 (3×)
6. extractionextracted with EtOAc (3×)
7. washThe combined EtOAc extracts were washed with brine
8. dry with materialdried (MgSO4)
9. concentrationconcentrated to dryness