Reaction #1810

Reaction equation

EDC

HCl.H2N-Gly-Asp(OBn)-Phe-OBn

diisopropylethylamine

dimethylformamide

HOBT

→

3-[6-Amino-2-pyridinyl]-propionyl-glycyl-(L)-aspartyl-(L)-phenylalanine

Yield 10.0%

Solvents

ethanol

Conditions

Workup

1. 1
   Temperatureto warm to room temperature
2. 2
   Otherthe dimethylformamide was removed on a rotovap at 40° C
3. 3
   OtherThe residue was partitioned between ethyl acetate and water
4. 4
   Washthe organic layer rinsed one time with water, two times with 5% citric acid
5. 5
   OtherThe organic solution was dried on sodium sulfate
6. 6
   Otherthe ethyl acetate removed
7. 7
   OtherFrom this solution was recovered 85 mg (55%) of the starting peptide
8. 8
   Extractionextracted with dichloromethane
9. 9
   Otherthus obtained on silica gel using 5% methanol/methylene chloride
10. 10
    OtherThe product thus obtained (30 mg, 0.5 mmol)
11. 11
    OtherThe flask was flushed with H2
12. 12
    workup.ADDITIONso an additional 7 mg of 10% Pd/C was added
13. 13
    OtherAfter 24 additional hours, the solvents were removed
14. 14
    Othera roto-evaporator
15. 15
    workup.ADDITIONthe residue treated with 1% acetic acid in water
16. 16
    FiltrationThe solution was filtered
17. 17
    Otherpurified

Procedure

3-(2-[6-Aminopyridyl])-propionic acid (63 mg, 0.28 mmol), HOBT (50 mg, 0.37 mmol), HCl.H2N-Gly-Asp(OBn)-Phe-OBn (155 mg, 0.28 mmol) and diisopropylethylamine were combined in 7 ml of dry dimethylformamide. The reaction mixture was cooled to 0° C. EDC (68 mg, 0.35 mmol) was added in one portion, the reaction mixture allowed to warm to room temperature and placed under argon. After 18 hours, the dimethylformamide was removed on a rotovap at 40° C. The residue was partitioned between ethyl acetate and water, and the organic layer rinsed one time with water, two times with 5% citric acid, once again with water, twice with 5% sodium bicarbonate solution, again with water, and finally one time with brine. The organic solution was dried on sodium sulfate, and the ethyl acetate removed. From this solution was recovered 85 mg (55%) of the starting peptide. The combined aqueous rinses were adjusted to pH 9 using dilute NaOH, and extracted with dichloromethane. Chromatography was carried out on the oil thus obtained on silica gel using 5% methanol/methylene chloride. The product thus obtained (30 mg, 0.5 mmol) was dissolved in 5 ml of ethanol, and treated with 10% Pd/C (wetted with butanol) (10 mg). The flask was flushed with H2, and stirred under an atmosphere of H2 for 18 hours. After this time, TLC showed some starting material, so an additional 7 mg of 10% Pd/C was added, and the reaction mixture placed again under H2. After 24 additional hours, the solvents were removed using a roto-evaporator, and the residue treated with 1% acetic acid in water. The solution was filtered, and purified using HPLC. This afforded 19 mg of the desired product as a white powder. Overall yield: 10%. NMR (CD3OD): 7.79 ("t", 1H, J=8.1); 7.22 (m, 5H); 6.81 (d, 1H, J=9.0); 6.73 (d, 1H, J=7.2); 4.74 ("t", 1H, J=5.1); 4.61 (m, 1H); 3.85 (s, 2H); 3.18 ("a-b"d, 1H, J=4.5); 3.02 (m, 3H); 2.79 ("a-b"d, 1H, J=5.0); 2.66 (m, 3H). Mass spectrum: 484 (m-H)- ; 598 (M+CF3COO-). EA: Calculated for C23H27N5O7.2.5 F3C3O2H.2.5 H2O: C, 41.24; H, 4.22; N, 8.59. Found: C, 41.30; H, 4.26; N, 8.81.

Source