Nsc and Fmoc Nα-amino protection for solid-phase peptide synthesis:: a parallel study

The 2-(4-nitrophenylsulfonyl)ethoxycarbonyl (Nsc) group is an alternative to Fmoc for N-alpha-protection in solid-phase peptide synthesis. Nsc-amino acids may be particularly suitable for automatic synthesizers, in which the amino acids are stored in solution, and the incorporation of residues prone to racemization such as Cys and His. Owing to the hydrophilicity of the Nsc group, these derivatives are useful for the preparation of protected peptides in convergent solid-phase peptide synthesis strategies.