Synthesis and Evaluation of the β-Turn Properties of 4-Amino-1,2,4,5-tetrahydro-2-benzazepin-3-ones and of Their Spirocyclic Derivative

A series of 4-amino-tetrahydro-2-benzazepin-3-one derivatives (Ac–Aba–Xxx–NHMe) were prepared as tetrapeptide mimetics. Considering the structural resemblance with the so-called Freidinger lactams, their propensity to adopt a β-turn conformation was investigated by NMR spectroscopy (solvent and temperature dependence) and molecular modeling. Interestingly, most of these lactams adopt extended conformations, only the spiro-benzazepinone 9 has a strong preference for the formation of a β-turn. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)