Benzyloxycarbonyl protecting

Tpte [2-[(4-tritylphenyl)thio]ethyl] Z = Cbz benzyloxycarbonyl protecting group... 

Alternatively the benzyloxycarbonyl protecting group may be removed by treat ment with hydrogen bromide m acetic acid... 

Hydrogen bromide may be used to remove either the benzyloxycarbonyl or tert butoxycarbonyl protecting group The benzyloxycarbonyl protect mg group may also be removed by catalytic hydrogenolysis... 

The benzyloxycarbonyl protecting group for amines is introduced in high yield using benzyl imidazole-carboxylate with a catalytic amount (5%) of dimethylamino-pyridine.[1953... 

BW Erickson, RB Merrifield. Use of chlorinated benzyloxycarbonyl protecting groups to eliminate Ne-branching at lysine during solid-phase peptide synthesis. J Am Chem Soc 95, 3757, 1973. 

Knudsen, K.R. and Holden, J. and Ley, S.V. and Ladlow, M. (2007). Optimization of Conditions for 0-Benzyl and A-Benzyloxycarbonyl Protecting Group Removal using an Automated Flow Hydrogenator. Synth. Catal, 349, 535-538. 

Scheme 8 The Four fert-Butoxycarbonyl/Benzyloxycarbonyl-Protected Peptide Nucleic Acid Monomers...

The first solid-phase peptide synthesis reported by Merrifield had some disadvantages, which were corrected in later versions of this synthesis. The main improvements were the replacement of benzyloxycarbonyl protective groups by the TFA-labile Boc protection, and the use of TFA-resistant linkers cleavable by HF. 

Like the benzyloxycarbonyl protecting group, the Boc group may be removed by treatment with hydrogen bromide (it is stable to hydrogenolysis, however) ... 

To add a leucine residue to the N terminus of the ethyl ester of Z-Phe-Gly, the benzyloxycarbonyl protecting group must first be removed. This can be accomplished by hydrogenolysis. 

Enzymatic methods are now preferred for the commercial production of aspartame from aspartate and phenylalanine. Typically, these use thermolysin (EC 3.4.24.4 derived from Bacillus spp.) to couple benzyloxycarbonyl-protected aspartate (Z-asp) with phenylalanine methyl ester. The resulting Z-APM is then deprotected using standard methods [14-18]. Numerous enzymatic methods have been reported [10]. 

Mitchell et al. reported 37 the synthesis of chiral dendrimers using L-glutamic acid as the monomer. Construction (Scheme 7.12) was accomplished convergently beginning with A-benzyloxycarbonyl protected L-glutamic acid, which was converted to the bis(ac-tivated ester) (50) by reaction with A-hydroxysuccinimide, DCC, and a catalytic amount... 

When it is time to remove the benzyloxycarbonyl protective group, the compound is reacted with hydrogen in the presence of a catalyst. The cleavage of the benzyl group by hydrogenolysis (see Section 23.3) is followed by spontaneous decarboxylation of the carbamic acid. An example is provided by the following equation ... 

Various heteroatom nucleophiles carry out an SN reaction at the carboxyl carbon of Z-chloride (whereby they displace a chloride ion). The most important nucleophiles of this type are amino acids. They give rise to benzyloxycarbonyl-protected amino acids (Z-protected amino acids Figure 6.29).They are standard components for peptide synthesis (cf. Figure 6.26). 

Catalytic hydrogenation of unsaturated benzyloxycarbonyl-protected lactam 105 using Pearlman s catalyst gave saturated lactam 196 in 99% yield (Scheme 96 <1996J(P1)123>). 

---