Synthese und Konformationsanalyse von Pyranophanonen und Pyrylophanium‐Verbindungen mit intraannularen Substituenten

Synthesis and Conformational Analysis of Pyranophanones and Pyrylophanium Compounds with Intraannular Substituents The synthesis of [3.3]dithiapyranophanone 6 and 11 is accomplished by use of the two‐components‐dilution‐principle. Pyrolysis of their bis(sulfones) 7 and 12 gives the [2.2]pyranophanones 8, 9 and 13. Under preservation of conformation the intraannular carbonyl‐function is used for the synthesis of methylpyranophanoles 14, 16 and 17. The synthesis of pyrylophanium compounds 15 and 18 is possible by elimination in trifluoroacetic acid. 6 exhibits anti‐conformation within its crystal‐structure and like 7 reveals temperature‐dependent behavior in solution. Using 6 as an example, a combination of ¹³C‐NMR‐spectroscopy, forcefield‐calculation and computer‐simulation is applied for the first time to give evidence for molecular‐dynamic processes of cyclophanes. 8 and 9 are the syn‐ and anti‐conformers of the desired product, as shown by X‐ray structural analysis. 13 reveals anti‐conformation within its crystal structure as well as in solution. The conformational analysis of other new phanes described here is based on the ¹H‐NMR‐spectra of these pyrolysis products. As expected the intraannular substituents of Pyrylophanium‐lons 15 and 18 show the characteristic upfield‐shift within their ¹H‐NMR‐spectra.