Preservation of the Fmoc protective group under alkaline conditions by using CaCl2.: Applications in peptide synthesis

CaCl2 is shown to dramatically increase the lifetime of the Fmoc protective group in alkaline iPrOH-H2O bur has little effect on hydrolytic processes. This enables efficient preparation of Fmoc-protected peptide segments by saponification of the corresponding C-terminal methyl or benzyl esters. Similarly, protected peptide segments prepared by Fmoc/tBu solid-phase synthesis can be, selectively released from the support by CaCl2-catalyzed alkaline hydrolysis of an N-acylurea-based linker. (C) 1998 Elsevier Science Ltd. All rights reserved.