Tert-Butoxycarbonyl carbamate-derived

When 147 reacts with serine (58), in the presence of an amine base, the product is 148, which is called Cbz-valine. The Cbz-NH unit is actually a benzyl carbamate, and this is an excellent way to protect the N-terminus of an amino acid. The corresponding er -butoxycarbonyl chloride derivative (149) cannot be isolated because it is too unstable. Attempts to prepare it from tert-butyl alcohol lead to formation of isobutylene (2-methylpropene). 

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