Alkyne-Linked 2,2-Disubstituted-indolin-3-one Oligomers as Extended β-Strand Mimetics

The design, synthesis, and structural analysis of a new foldamer that mimics an extended beta-sheet are presented. The nonpeptidic mimetic is based on a series of 2,2-disubstituted-indolin-3-one groups linked through their 4,7-positions by an alkyne spacer. An intramolecular hydrogen bond between the carbonyl of one indolinone subunit and the proximal. NH of another subunit imposes a conformation that mimics the side chain positioning on a beta-strand. X-ray crystallographic studies support the presence of this intramolecular hydrogen bond. The described approach allows extension of the scaffold to longer oligomers that will form the basis of new mimetics for the disruption of therapeutically relevant protein-protein interactions that rely on the contacts of side chain residues on two beta-strands.