title: Stereoselective synthesis of (E)-2-en-4-ynoic acids with ynolates: catalytic conversion to tetronic acids and 2-pyrones.
abstract: A highly torquoselective olefination of alkynoates to provide functionalized tetrasubstituted olefins, (E)-2-en-4-ynoic acids, is described. Addition of Brønsted acids dramatically switched the mode of the Ag(I)-catalyzed cyclization of the resulting enyne carboxylic acids to give either tetronic acids or 2-pyrones.
authors.affiliation: Interdisciplinary Graduate School of Engineering Sciences, Kyushu Unviersity, 6-1, Kasugako-en, Kasuga 816-8580, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Shindo
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011753:Pyrones / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D002264:Carboxylic Acids; D005663:Furans; D011753:Pyrones; C003422:tetronic acid