Comparative studies of Nsc and Fmoc as N-alpha-protecting groups for SPPS

2-(4-Nitrophenyl)sulfonylethoxycarbonyl (Nsc) is an alternative base-labile N-alpha-protecting group to 9-fluorenylmethoxycarbonyl (Fmoc) for amino ac ids. The UV spectrum of the Nse group exhibits moderate absorption at 380 n m which is excellent for real-time monitoring of the deprotection process. It also decreases the rearrangement of X-Asp, which can be a serious proble m in SPPS. Copyright (C) 1999 European Peptide Society and John Wiley & Son s, Ltd.