New β-Strand Templates Constrained by Huisgen Cycloaddition

New peptidic templates constrained into a beta-strand geometry by linking acetylene and azide containing P-1 and P-3 residues of a tripeptide by Huisgen cycloaddition are presented. The conformations of the macrocycles are defined by NMR studies and those that best define a beta-strand are shown to be potent inhibitors of the protease calpain. The beta-strand templates presented and defined here are prepared under optimized conditions that should be suitable for targeting a range of proteases and other applications requiring such a geometry.