Introduction To Cbz

Carbobenzoxy (Cbz) is a very old amino protecting group discovered by Bergmann in 1932, but it is still used today. Its advantages are as follows. First, the preparation of reagents and the introduction of protecting groups are relatively easy. Second, Cbz-amino acids and peptides are easy to crystallize and relatively stable. Third, Cbz-amino acids are not easy to racemize when activated, and the Cbz group can be selectively removed by a variety of mild methods.

Introduction of Cbz

The introduction of Cbz is generally carried out using Cbz-Cl. Free amino groups can easily react with Cbz-Cl under alkaline conditions controlled by NaOH or NaHCO₃ to obtain Cbz-amino acids.

Removal of Cbz

There are several main methods for removing Cbz.

Catalytic hydrogenolysis
Acidic cleavage
Na/NH₃ (liquid) reduction

Generally speaking, the commonly used method for removing Cbz in the laboratory is catalytic hydrogenolysis, but when there are groups in the molecule that are sensitive or passivated to catalytic hydrogenolysis, we must use chemical methods such as acid hydrolysis or Na/NH₃ (liquid) reduction to remove the Cbz.

If you want to learn more, please feel free to contact us.