title: Intramolecular Hydrogen Bonding and Linear Pentapyrrole Conformation.
abstract: Three new linear pentapyrrole rubinoid analogs: 2,3,7,8,17,18,22,23-octamethyl-12,13-bis-(2-carboxyethyl)-1,10,15,24,25,27,28,29-octahydro-27H-pentapyrrin-1,24-dione and 2,3,8,12,13,17,22,23-octamethyl-7,18-bis-(2-carboxyethyl)-1,10,15,24,25,26,27,28,29-octahydro-27H-pentapyrrin-1,24-dione, and its 7,18-dihexanoic acid analog were synthesized, respectively, from 2,3,7,8-tetramethyl-(10H)-dipyrrin-2-one, from 2,3,8-trimethyl-7-[2-(methoxycarbonyl)ethyl]-(10H)-dipyrrinone, and 2,3,8-trimethyl-7-[5-(methoxycarbonyl)pentyl]-(10H)-dipyrrinone.13C NMR and1H NMR measurements in (CD3)2SO confirmed the pentapyrrole structures, while1H NMR data indicate intramolecular hydrogen bonding between the CO2H and dipyrrinone groups. Molecular mechanics modeling studies suggest stable U-shape conformations capable of encapsulating small planar aromatic molecules.
authors.affiliation: Department of Chemistry, Northwest Nazarene University, Nampa, ID 83686.
authors.forename: D Timothy
authors.initials: DT
authors.lastname: Anstine
authors.affiliation: Department of Chemistry, University of Nevada, Reno, Nevada, 89557-0216 USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Lightner
keywords: Hydrogen Bonding; NMR; Pyrroles
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