反应详情

温度

40 °C

A 50 ml round-bottom flask containing a magnetic stirring bar was charged with 120.5 mg (0.63 mmole) of 6-formyl pterin, prepared by the method of Viscontini, et al., (1) (2) 490.2 mg (156 mmole, 2.47 equiv.) of H-PABA-L-TME and 4 ml of glacial acetic acid (HOAc). With stirring the H-PABA-L-TME dissolved, but the yellow aldehyde remained in suspension. The flask was flushed with argon as 3-4 ml of trifluoroacetic acid (TFA) was slowly added to effect complete dissolution of the suspended solids. Stirring was continued for an additional 30 minutes from this point. Most of the solvent then was removed from the dark brown solution by gentle warming (40° C.) on the rotary evaporator (water aspirator). The moist brown residue was taken to dryness under high vacuum (0.05 mm Hg) at room temperature overnight with the flask wrapped in aluminum foil to exclude light. A brown foam or glass resulted. The vacuum was broken and argon was bled into the flask. To the brown foam was added 4 ml of HOAc, and with vigorous swirling and stirring (under argon) the residue was dislodged from the walls of the flask to form a light yellow-brown suspension. Dimethylamine borane, 37.2 mg (0.631 mmole, 1 equiv.) was added to the stirred suspension; the color rapidly changed to orange-brown and nearly all of the solid dissolved. After an hour HOAc (8-10 ml) was used to rinse down the neck and walls of the flask. The reaction mixture was concentrated with gentle heating (40°) on the rotary evaporator to a viscous residue. Two 25 ml portions of toluene were successively added to the residue, mixed, then stripped in vacuo which gentle warming to remove HOAc as its toluene azeotrope. The final toluene-damp residue was dried to a brown foam under high vacuum at room temperature overnight. To the flask was added 30 ml of EtOAc. The foam was scraped from the walls of the flask with a metal spatula to form a suspension, which was left standing in the refrigerator overnight. The insoluble yellow-orange solid was separated from the yellow supernatant by centrifugation. The pelleted solid was resuspended in EtOAc and recentrifuged three times until the final EtOAc wash was colorless. Finally, the pelleted solid was resuspended in a small volume of EtOAc, collected on a coarse fitted glass fiber under argon in a pressure filtration apparatus, washed with several small portions of EtOAc and dried by flowing argon through the collected filter cake under positive pressure for an hour.

1. additionA 50 ml round-bottom flask containing a magnetic stirring bar
2. dissolutiondissolved
3. customThe flask was flushed with argon as 3-4 ml of trifluoroacetic acid (TFA)
4. additionwas slowly added
5. dissolutiondissolution of the suspended solids
6. customMost of the solvent then was removed from the dark brown solution
7. customon the rotary evaporator (water aspirator)
8. waitThe moist brown residue was taken to dryness under high vacuum (0.05 mm Hg) at room temperature overnight with the flask
9. customA brown foam or glass resulted
10. stirringwith vigorous swirling and stirring (under argon) the residue
11. customto form a light yellow-brown suspension
12. dissolutiondissolved
13. washto rinse down the neck and walls of the flask
14. concentrationThe reaction mixture was concentrated
15. temperaturewith gentle heating (40°)
16. customon the rotary evaporator to a viscous residue
17. additionTwo 25 ml portions of toluene were successively added to the residue
18. additionmixed
19. temperaturegentle warming
20. customto remove HOAc as its toluene azeotrope
21. dry with materialThe final toluene-damp residue was dried to a brown foam under high vacuum at room temperature overnight
22. additionTo the flask was added 30 ml of EtOAc
23. customto form a suspension, which
24. waitwas left
25. customstanding in the refrigerator overnight
26. customThe insoluble yellow-orange solid was separated from the yellow supernatant by centrifugation
27. washwash
28. customcollected on
29. customa coarse fitted glass fiber under argon
30. filtrationin a pressure filtration apparatus
31. washwashed with several small portions of EtOAc
32. customdried
33. filtrationfilter cake under positive pressure for an hour