title: Homorubins and Homoverdins.
abstract: The syntheses are described for centrally expanded bilirubin analogs:b-homorubins with propionic and butyric acid groups in the positions corresponding to the propionic acids of bilirubin. Their syntheses were accomplished by coupling two equivalents of a reactive monopyrrole (5-(bromomethylene)pyrrolin-2-one) to a dipyrrylethane. The correspondingb-homoverdins and dehydro-b-homoverdins were prepared by dehydrogenating the rubins or their dimethyl esters using DDQ. As supported by NMR measurements and molecular mechanics calculations, the homorubins are found to engage in conformation-determining intramolecular hydrogen bonding between the dipyrrinone and carboxylic acid moieties. Likewise, the homoverdins are believed to favor intramolecularly hydrogen-bonded conformations.
authors.affiliation: CIMA Labs, Inc., Eden Prairie, MN 55344 USA.
authors.forename: William P
authors.initials: WP
authors.lastname: Pfeiffer
authors.affiliation: Milliken & Company, P. O. Box 1926, Spartanburg, SC 29304 USA.
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Dey
authors.affiliation: Institut für Organische Chemie, Abteilung für Organische Chemie, Johannes Kepler-Universität Linz, Altenbergerstr. 69, A-4040 Linz, Austria.
authors.forename: Heinz
authors.initials: H
authors.lastname: Falk
authors.affiliation: Department of Chemistry, University of Nevada, Reno, Nevada, 89557-0216 USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Lightner
keywords: Bilirubinoids; Conformational Analysis; Molecular Structure; Synthesis
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