Carboxybenzyl or Cbz or Z is an amine protecting group in organic synthesis.[1] It is commonly used in peptide synthesis and is formed by reacting an amine with benzyl chloroformate and a weak base:
It is used to protect amines from electrophiles. The protected amine can be deprotected by catalytic hydrogenation or treatment with HBr, yielding a terminal carbamic acid that then readily decarboxylates to yield the free amine.
The method was first used by Max Bergmann in 1932 for the synthesis of peptides.[2]