title: Fluorescent penta- and hexaene fatty acids by a Wittig-Horner/elimination strategy.
abstract: Molecular fluorescent probes have revolutionized biochemical and biophysical studies in the last decades, but with regard to lipids there has been a lack of combining the slim shape of saturated acyl chains with fluorescent properties. Our strategy to pentaene and hexaene fatty acids builds upon commercially available 4-(E)-decenal, which is subjected to a Wittig-Horner reaction after chlorination in α-position. DBU-mediated β-elimination of HCl proceeding the olefination establishes a highly conjugated system to which a salt-free Wittig reaction adds a final double bond leading to a good (Z)-selectivity of 83-86%. The double bond geometry can be optionally isomerized with I(2) to furnish the all-(E)-species. The five conjugated alkene moieties result in a longest-wavelength absorption maximum of about 350 nm. A red-shift to 380 nm was realized by addition of another double bond employing a common Wittig-Horner prolongation sequence. Stokes shifts of about 7300 and 7800 cm(-1), respectively, were observed.
authors.affiliation: Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077 Göttingen, Germany.
authors.forename: Lukas J
authors.initials: LJ
authors.lastname: Patalag
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Werz
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D005227:Fatty Acids; D005456:Fluorescent Dyes