Two new beta-strand mimics.

In a previous report, Nowick and co-workers described beta-strand mimic A, which duplicates the structure and hydrogen-bonding pattern of one edge of a tetrapeptide in a beta-strand conformation (Nowick, J. S.; Pairish, M.; Lee, I. Q.; Holmes, D. L.; Ziller, J. W. J. Am. Chem. Soc. 1997, 119, 5413). Beta-strand mimic A is composed of a 5-amino-2-methoxybenzoic acid unit linked to a 5-hydrazino-2-methoxybenzamide unit by means of an acylhydrazine group. This paper introduces two related beta-strand mimics (B and C) and reports their comparison to beta-strand mimic A. Beta-strand mimic B is composed of a 5-amino-2-methoxybenzoic acid unit linked by a diacylhydrazine group to a fumaramide unit; beta-strand mimic C is composed of a 5-amino-2-methoxybenzoic acid unit linked by a diacylhydrazine group to a peptide. Beta-strand mimics A-C were connected to tripeptide (Phe-Ile-Leu) groups by means of 1,2-diaminoethane diurea turn units to form artificial beta-sheets 1-3. 1H NMR studies, involving ROESY, chemical shift, coupling constant, and variable temperature experiments, reveal that 1-3 adopt hydrogen-bonded antiparallel beta-sheet conformations and establish that all three templates are viable beta-strand mimics.