Effects of preorganization and hydrogen bonding on intramolecular chemical ligation of (N)-and (O)-acyl isopeptides

The ease of intramolecular N-to N-and O-to N-acyl transfers in (N)-acyl isopeptides and (O)-acyl isopeptides was found to be governed by preorganization rationalized in terms of geometrical and energetic characteristics of the linear isopeptide backbone, which depends on the chain length. Intramolecular hydrogen bonding was found another important factor of reactivity able to stabilize the chemical ligation transition state.