Sodium triacetoxyborohydride → 2(R)-(3,4-methylenedioxy-benzylamino)-3-methylbutyric acid benzyl ester

HRID 1006113Notes

Reaction equation

HRID 1006113 reaction equation
[CH2:1]([O:8][C:9](=[O:15])[C@@H:10]([CH:12]([CH3:14])[CH3:13])[NH2:11])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(O[BH-](O[C:26](=[O:28])[CH3:27])OC(=O)C)(=O)C.[Na+]>C(Cl)Cl>[CH2:1]([O:8][C:9](=[O:15])[C@H:10]([NH:11][CH2:14][C:12]1[CH:13]=[CH:27][C:26]2[O:28][CH2:1][O:8][C:9]=2[CH:10]=1)[CH:12]([CH3:13])[CH3:14])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

4

Reactant 2

HCID 5049666Sodium triacetoxyborohydrideHCID 7350007Benzyl D-valinate

Product 1

HCID 542486302(R)-(3,4-methylenedioxy-benzylamino)-3-methylbutyric acid benzyl esterYield 170.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

To a solution of D-valine benzyl ester free base (12.92 g, 62 mmol) in dry methylene chloride (120 mL) was added 3,4-(methylenedioxy)phenyl methanol (9.45 g, 62 mmol) and sodium triacetoxyborohydride (18.50 g, 86.8 mmol). After 15 h, the reaction mixture was quenched with saturated aqueous sodium bicarbonate (120 mL) and the aqueous layer was separated and extracted with methylene chloride. The combined methylene chloride layers were washed with brine, dried over magnesium sulfate, and concentrated. The residue was chromatographed (300 g SiO2, 5% ethyl acetate-hexanes) to afford 2(R)-(3,4-methylenedioxy-benzylamino)-3-methylbutyric acid benzyl ester (18 g) as a colorless oil.

Workup

  1. customthe reaction mixture was quenched with saturated aqueous sodium bicarbonate (120 mL)
  2. customthe aqueous layer was separated
  3. extractionextracted with methylene chloride
  4. washThe combined methylene chloride layers were washed with brine
  5. dry with materialdried over magnesium sulfate
  6. concentrationconcentrated
  7. customThe residue was chromatographed (300 g SiO2, 5% ethyl acetate-hexanes)

Sources & evidence

ORD record
ord-75a41f1dfd444fbf9a257459c20f28f2
Source dataset
uspto-grants-2004_09
Patent number
US06787559B2

Reaction notes

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