Other Acid-Labile Carbamates

Benzyl carbamate protection (Cbz or Z group see Table 10.15) was initially chosen by Merrifield for solid-phase peptide synthesis [255], The strongly acidic conditions required for its solvolysis (30% HBr in AcOH, 25 °C, 5 h) demanded the use of an acid-resistant nitrobenzyl alcohol linker. Z-protection of the a-amino group in solid-phase peptide synthesis was, however, quickly abandoned and replaced by the more acid-labile Boc protection. Benzyl carbamates can be cleaved by strongly ionizing 

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Although there are other convenient procedures for the conversion of sulphides into sulphoxides and sulphones, the phase-transfer catalysed reaction using Oxone has the advantage that the oxidation can be conducted in the presence of other readily oxidized groups, such as amines, alkenes, and hydroxyl groups, and acid-labile groups, such as esters and carbamates [6, 7], Hydrolysis of very acid-labile groups, such as ketals, can result in production of the keto sulphone. 

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