Sodium borohydride → 4-Tert-butoxycarbonylamino-3-hydroxy-5-phenyl-pentanoic acid ethyl ester

HRID 987928Notes

Reaction equation

HRID 987928 reaction equation
[CH2:1]([O:3][C:4](=[O:24])[CH2:5][C:6](=[O:23])[CH:7]([NH:15][C:16]([O:18][C:19]([CH3:22])([CH3:21])[CH3:20])=[O:17])[CH2:8][C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1)[CH3:2].[BH4-].[Na+]>C(O)C>[CH2:1]([O:3][C:4](=[O:24])[CH2:5][CH:6]([OH:23])[CH:7]([NH:15][C:16]([O:18][C:19]([CH3:21])([CH3:20])[CH3:22])=[O:17])[CH2:8][C:9]1[CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=1)[CH3:2]

Participants

4

Reactant 2

HCID 4311764Sodium borohydrideHCID 10871382Ethyl 4-{[(tert-butoxy)carbonyl]amino}-3-oxo-5-phenylpentanoate

Product 1

HCID 139123654-Tert-butoxycarbonylamino-3-hydroxy-5-phenyl-pentanoic acid ethyl esterYield 66.5%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

A mechanically stirred solution of 4-tert-butoxycarbonylamino-3-oxo-5-phenyl-pentanoic acid ethyl ester (115 g, 0.343 mol) in ethanol (450 ml) at 0° C. under nitrogen was treated portionwise with sodium borohydride (4.43 g, 0,117 mol) over 30 minutes, producing a thick slurry. The reaction mixture was quenched by the dropwise addition of glacial acetic acid (26 ml) at 0° C. under nitrogen. The slurry was then poured onto a mixture of dichloromethane (400 ml) and a 1M aqueous hydrogen chloride solution (400 ml) in a separating funnel. The organic layer was removed and the aqueous solution extracted with dichloromethane (180 ml). The combined organic solutions were washed sequentially with water (200 ml), 5% aqueous sodium hydrogen carbonate solution (200 ml) and brine (200 ml, and dried (anhydrous magnesium sulfate). The solvents were removed in vacuo to give an off-white solid which was recrystallised from methylcyclohexane/ethyl acetate providing 4-tert-butoxycarbonylamino-3-hydroxy-5-phenyl-pentanoic acid ethyl ester (77 g, 66%).

Workup

  1. customproducing a thick slurry
  2. customThe reaction mixture was quenched by the dropwise addition of glacial acetic acid (26 ml) at 0° C. under nitrogen
  3. additionThe slurry was then poured onto a mixture of dichloromethane (400 ml)
  4. customThe organic layer was removed
  5. extractionthe aqueous solution extracted with dichloromethane (180 ml)
  6. washThe combined organic solutions were washed sequentially with water (200 ml), 5% aqueous sodium hydrogen carbonate solution (200 ml) and brine (200 ml
  7. dry with materialdried (anhydrous magnesium sulfate)
  8. customThe solvents were removed in vacuo
  9. customto give an off-white solid which
  10. customwas recrystallised from methylcyclohexane/ethyl acetate

Sources & evidence

ORD record
ord-84d708c5dab848bface90b0fb00ac560
Source dataset
uspto-grants-2003_10
Patent number
US06632826B1

Reaction notes

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