A New Robust and Versatile Tetradentate Linker for Amides To be Cleaved under Mild Conditions by Unusual Complexation of the Amide Nitrogen to Cu++

Abstract The concept of weakening amide bonds by the rather unusual forced complexation of nitrogen to Cu++ is not limited to tridentate ligands and was extended in this work to tetradentate ligands as well. The use of cyclic tetradentate ligands was to no avail, but an open‐chain and more‐flexible tetradentate ligand allowed mild cleavage by methanolysis after complexation. The principle was applied to the development of a new linker for solid‐phase chemistry, which was proven to be extremely robust, yet allowed mild cleavage after activation by Cu++ complexation. Its stability and versatility was demonstrated by the successful application to a whole plethora of different types of reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)