title: The Stille reaction in the synthesis of the C37-norcarotenoid butenolide pyrrhoxanthin. Scope and limitations.
abstract: The sequential Stille cross-coupling reactions of the dihalogenated gamma-alkylidenebutenolide 7 with stannanes 9 and 6 afforded the carbon skeleton of pyrrhoxanthin, a highly functionalized C7'-C8' acetylenic C37-norcarotenoid butenolide. Although the first halogen-selective Stille coupling takes place in 90% yield at ambient temperature, double isomerization of the Z,E- to the E,Z-C7'-C10' enyne, likely induced by the catalyst, accompanyied the bond formation, leading to 9'Z-20 and, ultimately, to 9'Z-pyrrhoxanthin 9'Z-1.
authors.affiliation: Departamento de Química Organica, Facultade de Química, Universidade de Vigo, Lagoas Marcosende, E-36310, Vigo, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Vaz
authors.forename: Marta
authors.initials: M
authors.lastname: Domínguez
authors.forename: Rosana
authors.initials: R
authors.lastname: Alvarez
authors.forename: Angel R
authors.initials: AR
authors.lastname: de Lera
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002338:Carotenoids / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure
chemical_list: C520451:pyrrhoxanthin; D002338:Carotenoids; D002244:Carbon; C004511:butenolide; D015107:4-Butyrolactone