Characterization of Quinoline Derivatives. Part 3. Mass Spectrometry and X-ray Crystallography of Biologically Interesting Arylquinolines

The structural characterization of a novel series of biologically interesting arylquinolines based on four-ring fused heterocyclic systems is carried out. Chlorinated precursors 1-5 as well as final products 6-8, active as potent and selective 5-HT3 receptor antagonists, are characterized in the gas phase by low- and high-resolution mass spectrometry and tandem mass spectrometry. For the 4-methyl-1-piperazinylbenzophenanthridine derivative 6 the crystal and molecular structures were also determined. These data, compared to those obtained for its analogous benzopyrane (7) and benzoxepine (8) derivatives, allow for an evaluation of the influence exerted by the ring fused at the face c of the quinoline on the conformational properties of the molecule. (C) 1998 Elsevier Science B.V. All rights reserved.