Beiträge zur Chemie der Pyrrolpigmente, 16. Mitt.: 5-5-Methyliden-(5H-pyrrolyl-2-methyliden)-3-pyrrolin-2-on — eine Partialstruktur von Gallenpigmenten

摘要

By investigation of model systems related to 5-5-methylidene-(5H-pyrrolyl-2-methylidene)-3-pyrrolin-2-one by means of pK- and Lanthanide induced shift measurements (usingPDIGM-calculations),1H-NMR-, IR-, and UV-spectroscopy andPPP-calculations an intramolecular hydrogen bond has been shown to be characteristic of this bile pigment partial structure. As a consequence of this bond the system is coplanar (in solution) in contrast to the recently studied pyrromethenones and arylmethylidenepyrrolinones which have a twisted conformation at the methine single bond.