Semipermanent p-nitrobenzyloxycarbonyl ( pNZ) protection of Orn and Lys side chains: prevention of undesired α-Fmoc removal and application to the synthesis of cyclic peptides

Abstract

Semipermanent side-chain protection of Orn and Lys with p-nitrobenzyloxycarbonyl ( pNZ) for Fmoc/ t Bu chemistry does not result in the unwanted removal of α-Fmoc that occurs when groups such as Alloc are used for the same application. Furthermore, pNZ can be used in conjuction with p-nitrobenzyl ester ( pNB) to prepare cyclic peptides.