General description
PyClocK is the 6-chloro analog of PyBOP. Reaction of protected amino acids with PyClocK in the presence of base generates the corresponding 6-chloro-1-benzotriazolyl (Cl-OBt) ester. These active esters are considerably more reactive than those produced when using PyBOP or HBTU, owing to 6-chloro-1-hydroxybenzotriazole (Cl-HOBt) being more acidic than HOBt. PyClocK is an excellent coupling reagent for situations where carboxyl activation may be sluggish, such as cyclizations and fragment condensations, as unlike imminium-based reagents such as HBTU and HATU excess PyClocK cannot cause end-capping of peptide chains.
Associated Protocols and Technical Articles
Guide to Selection of Coupling Reagents
Analysis Note
Color (visual): white to slight yellow to beige
Appearance of substance (visual): powder
Identity (IR): conforms
Assay (HPLC, area%): ≥ 98.0 % (a/a)
Solubility (5% in NMP (1-Methyl-2-pyrrolidone)): clear
Legal Information
Novabiochem is a registered trademark of Merck KGaA, Darmstadt, Germany
- UPC:
- 41115700
- Condition:
- New
- Weight:
- 1.00 Ounces
- HazmatClass:
- No
- WeightUOM:
- LB
- MPN:
- 8510870025