PYRIDINIO-ISOALLOXAZINOPHANES AS MODEL SYSTEMS FOR ACTIVE-SITE COMPLEXES IN FLAVOENZYMES - SYNTHESES, X-RAY STRUCTURE ANALYSES AND SPECTROSCOPIC PROPERTIES

As model systems for active site complexes in flavoenzymes, flavin and nicotinamide analogues were linked together in cyclophane skeletons o f specific sterical structures. Elaborating this concept, we prepared [4]metacyclo[3](10,6)isoalloxazinophane (3), [4](3,1)pyridino[3](10,6) isoalloxazinophane (4), as well as the 16-methoxycarbonyl and the 16-c arboxy-late derivatives (2 and 34, resp.), of 4 by multistep syntheses . For the isoalloxazinophanes 2, 3, 4, and 34 X-ray structure analyses were performed and are discussed with regard to intramolecular intera ctions. Preliminary UV/Vis-spectroscopic results related to pi...pi in teractions in these isoalloxazinophanes are reported.