Methanol → 1-benzyl 4-methyl (2S)-2-aminobutanedioate

HRID 1510851Notes

Reaction equation

HRID 1510851 reaction equation
O=S(Cl)Cl.[NH2:5][C@H:6]([C:11]([O:13][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)=[O:12])[CH2:7][C:8]([OH:10])=[O:9].[CH3:21]O>>[NH2:5][C@@H:6]([CH2:7][C:8]([O:10][CH3:21])=[O:9])[C:11]([O:13][CH2:14][C:15]1[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1)=[O:12]

Participants

4

Reactant 3

HCID 887MethanolHCID 24386Thionyl ChlorideHCID 6994684H-Asp-OBzl

Product 1

HCID 129676051-benzyl 4-methyl (2S)-2-aminobutanedioate

Procedure

SOCl2 (6.60 mL, 90.5 mmol) was added drop-wise over 15 min to a cooled (ice-water) mixture of (S)-3-amino-4-(benzyloxy)-4-oxobutanoic acid (10.04 g, 44.98 mmol) and MeOH (300 mL), the cooling bath was removed and the reaction mixture was stirred at ambient condition for 29 hr. Most of the volatile component was removed in vacuo and the residue was carefully partitioned between EtOAc (150 mL) and saturated NaHCO3 solution. The aqueous phase was extracted with EtOAc (150 mL, 2×), and the combined organic phase was dried (MgSO4), filtered, and concentrated in vacuo to afford (S)-1-benzyl 4-methyl 2-aminosuccinate as a colorless oil (9.706 g). 1H NMR (DMSO-d6, δ=2.5 ppm, 400 MHz): δ 7.40-7.32 (m, 5H), 5.11 (s, 2H), 3.72 (app t, J=6.6, 1H), 3.55 (s, 3H), 2.68 (dd, J=15.9, 6.3, 1H), 2.58 (dd, J=15.9, 6.8, 1H), 1.96 (s, 2H). LC (Cond. 1): RT=0.90 min; LC/MS: Anal. Calcd. for [M+H]+ C12H16NO4: 238.11; found 238.22. Pb(NO3)2 (6.06 g, 18.3 mmol) was added over 1 min to a CH2Cl2 (80 mL) solution of (S)-1-benzyl 4-methyl 2-aminosuccinate (4.50 g, 19.0 mmol), 9-bromo-9-phenyl-9H-fluorene (6.44 g, 20.0 mmol) and Et3N (3.0 mL, 21.5 mmol), and the heterogeneous mixture was stirred at ambient condition for 48 hr. The mixture was filtered and the filtrate was treated with MgSO4 and filtered again, and the final filtrate was concentrated. The resulting crude material was submitted to a BIOTAGE® purification (350 g silica gel, CH2Cl2 elution) to afford (S)-1-benzyl 4-methyl 2-(9-phenyl-9H-fluoren-9-ylamino)succinate as highly viscous colorless oil (7.93 g). 1H NMR (DMSO-d6, δ=2.5 ppm, 400 MHz): δ 7.82 (m, 2H), 7.39-7.13 (m, 16H), 4.71 (d, J=12.4, 1H), 4.51 (d, J=12.6, 1H), 3.78 (d, J=9.1, NH), 3.50 (s, 3H), 2.99 (m, 1H), 2.50-2.41 (m, 2H, partially overlapped with solvent). LC (Cond. 1): RT=2.16 min; LC/MS: Anal. Calcd. for [M+H]+ C31H28NO4: 478.20; found 478.19.

Workup

  1. temperaturea cooled
  2. customthe cooling bath was removed
  3. customMost of the volatile component was removed in vacuo
  4. customthe residue was carefully partitioned between EtOAc (150 mL) and saturated NaHCO3 solution
  5. extractionThe aqueous phase was extracted with EtOAc (150 mL, 2×)
  6. dry with materialthe combined organic phase was dried (MgSO4)
  7. filtrationfiltered
  8. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-b4e8d427a7874c9d97c1b95c87d7ffd6
Source dataset
uspto-grants-2012_07
Patent number
US08211928B2

Reaction notes

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