HBTU — Coupling Reagent¶
Standard Peptide Synthesis Activator¶
Definition¶
HBTU (O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate) is the most widely used coupling reagent in Fmoc-SPPS.
Specifications¶
| Parameter | Typical Value |
|---|---|
| Purity | ≥99% |
| Appearance | White crystalline powder |
| Storage | -20 °C, desiccated |
| CAS number | 94790-37-1 |
Activation Mechanism¶
- HBTU deprotonates Fmoc-AA-OH (assisted by base/DIEA)
- Forms active ester (benzotriazolyl ester)
- Active ester reacts with free amine on peptide
Typical Conditions¶
| Parameter | Value |
|---|---|
| Equivalents | 2.9 eq (relative to AA) |
| Base | DIEA (6 eq) |
| Solvent | DMF |
| Activation time | 2–5 minutes |
| Coupling time | 30–60 minutes |
Advantages¶
- Widely available and cost-effective
- Good coupling efficiency for standard amino acids
- Compatible with automated synthesizers
Limitations¶
- May cause racemization for His, Cys
-
Lower reactivity for hindered amino acids (use HATU instead)
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Standard Peptide Synthesis Activator — Review the section above for key parameters, methods, and quality criteria.
- Activation Mechanism — Review the section above for key parameters, methods, and quality criteria.
- Typical Conditions — Review the section above for key parameters, methods, and quality criteria.
Key Takeaways¶
- Standard Peptide Synthesis Activator — Review the section above for key parameters, methods, and quality criteria.
- Definition — Review the section above for key parameters, methods, and quality criteria.
- Specifications — Review the section above for key parameters, methods, and quality criteria.
- Activation Mechanism — Review the section above for key parameters, methods, and quality criteria.
🔗 Related: HATU | DIC | Oxyma | Coupling Reaction