L-Tryptophan → L-Tryptophan, methyl ester

HRID 553064Notes

Reaction equation

HRID 553064 reaction equation
S(Cl)(Cl)=O.[NH2:5][C@H:6]([C:17]([OH:19])=[O:18])[CH2:7][C:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[NH:10][CH:9]=1.[C:20]([O-])([O-])=O.[Na+].[Na+]>CO.O>[CH3:20][O:18][C:17](=[O:19])[C@H:6]([CH2:7][C:8]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[NH:10][CH:9]=1)[NH2:5]

Participants

6

Reactant 3

HCID 6305L-TryptophanHCID 10340Sodium CarbonateHCID 24386Thionyl Chloride

Product 1

HCID 77980L-Tryptophan, methyl esterYield 98%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 962WaterSolvent

Procedure

Thionyl chloride (4.25 mL, 58.10 mmol, 2.4 eq) was added dropwise to a suspension of L-tryptophan (5.0 g, 24.48 mmol, 1.0 eq) in dry MeOH (50 mL) at −15° C. The cold bath was removed and the solution was stirred at room temperature for 24 h, then concentrated under vacuum at 40° C. gave a residue which was dissolved in H2O (75 mL) and then neutralized with Na2CO3 to a pH 8. Extraction with CHCl3 (3×50 mL) and dried over anhydrous MgSO4. Evaporation of the solvent gave the L-tryptophan methyl ester as a brick-red viscous oil (5.37 g, 98%); IR (liquid film) ν 1755 (CO), 3290 (NH) cm−1; 1H NMR (300 MHz, CDCl3) δH 1.78 (2H, s, —NH2), 3.10 (1H, dd, J=6.8 and 14.8 Hz, —CHαTrp), 3.32 (1H, dd, J=6.0 and 14.8 Hz, —CHβTrp), 3.80 (3H, s, OMe), 4.50 (1H, t, J=6.8 Hz, —CH—), 7.06 (1H, t, J=7.4 Hz, H-5′), 7.13 (1H, t, J=7.4 Hz, H-6′), 7.23 (1H, s, H-2′), 7.39 (1H, d, J=7.8 Hz, H-7′), 7.55 (1H, d, J=7.8 Hz, H-4′) and 8.47 (1H, s, pyrrol NH), which was sufficiently pure and used directly in the next step.

Workup

  1. customThe cold bath was removed
  2. concentrationconcentrated under vacuum at 40° C.
  3. customgave a residue which
  4. extractionExtraction with CHCl3 (3×50 mL)
  5. dry with materialdried over anhydrous MgSO4
  6. customEvaporation of the solvent

Sources & evidence

ORD record
ord-ef9ceee8628b4e6fa18d946c2bac5d2c
Source dataset
uspto-grants-2011_05
Patent number
US07951834B2

Reaction notes

Loading…