Reaction #696730

Reaction equation

3-(S)-[(benzyloxycarbonyl)amino]-2-(R,S)-hydroxy-4-methylpentanoic acid

pyridine

acetic anhydride

→

3-(S)-[(benzyloxycarbonyl)amino]-2-(R,S)-acetoxy-4-methyl pentanoic acid

Yield 80.0%

Solvents

ethyl acetate

Conditions

Workup

1. 1
   Washwashed with water (2×)
2. 2
   DryingThe organic layer was dried over magnesium sulfate
3. 3
   Filtrationfiltered
4. 4
   Otherevaporated in vacuo
5. 5
   Otherto give a thick oil
6. 6
   OtherThe residue was purified by column chromatography on silica gel with 15% methanol/dichloromethane

Procedure

To a solution of 3-(S)-[(benzyloxycarbonyl)amino]-2-(R,S)-hydroxy-4-methylpentanoic acid (1.70 g, 6.04 mmol) and pyridine (4.9 mL) was added acetic anhydride (5.7 mL, 6.17 g, 60.4 mmol) dropwise at room temperature. The reaction was allowed to stir overnight and was diluted with ethyl acetate and washed with water (2×). The organic layer was dried over magnesium sulfate, filtered and evaporated in vacuo to give a thick oil. The residue was purified by column chromatography on silica gel with 15% methanol/dichloromethane to afford 1.56 g (80%) of 3-(S)-[(benzyloxycarbonyl)amino]-2-(R,S)-acetoxy-4-methyl pentanoic acid as a light yellow viscous oil. FAB MS [M+H] m/z; Calcd: 324, Found: 324.

Source