Die massenspektrometrische Wasserabspaltung aus makrocyclischen Amino‐ketonen

The Mass Spectral Loss of Water from Macrocyclic Amino‐ketones Macrocyclic oxo‐lactams containing an N ‐alkylamino side chain are stable natural products. Their electron‐impact mass spectra are characterized by intensive [ M − H 2 O] + signals, the molecular ion signal itself is missing. Under electrospray ionization conditions, on the other hand, the [ M + 1] + ion is the only detected signal. The loss of water is explained in terms of an internal (thermal) Schiff ‐base formation, leading to a e.g. bicyclo[11.9.4]‐system. The alcohol corresponding to the macrocyclic ketones and/or lactams show an expected mass‐spectral behavior following well known rules.