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Snowden, Roger L.; Eichenberger, Jean‐Claude; Linder, Simon; Sonnay, Philippe

Internal Nucleophilic Termination in Acid‐Mediated Polyene Cyclizations. Part 3 : Synthetic Access to Didehydro and Methyl Didehydro Analogues of (±)‐Ambrox® : Synthetic Access to Didehydro and Methyl Didehydro Analogues of (±)‐<i>Ambrox</i><sup>®</sup>

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  • Medientyp: E-Artikel
  • Titel: Internal Nucleophilic Termination in Acid‐Mediated Polyene Cyclizations. Part 3 : Synthetic Access to Didehydro and Methyl Didehydro Analogues of (±)‐Ambrox® : Synthetic Access to Didehydro and Methyl Didehydro Analogues of (±)‐<i>Ambrox</i><sup>®</sup>
  • Beteiligte: Snowden, Roger L.; Eichenberger, Jean‐Claude; Linder, Simon; Sonnay, Philippe
  • Erschienen: Wiley, 2004
  • Erschienen in: Helvetica Chimica Acta
  • Sprache: Englisch
  • DOI: 10.1002/hlca.200490155
  • ISSN: 0018-019X; 1522-2675
  • Schlagwörter: Inorganic Chemistry ; Organic Chemistry ; Physical and Theoretical Chemistry ; Drug Discovery ; Biochemistry ; Catalysis
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  • Beschreibung: <jats:title>Abstract</jats:title><jats:p>Treatment of the unsaturated allenic alcohols (<jats:italic>E</jats:italic>)‐<jats:bold>7</jats:bold>, (<jats:italic>Z</jats:italic>)‐<jats:bold>7, 10, 13</jats:bold>, and <jats:bold>19</jats:bold> with an excess of FSO<jats:sub>3</jats:sub>H in 2‐nitropropane at −90° to −30° afforded, in 68–85% yield, diastereoisomer mixtures of racemic tricyclic ethers <jats:bold>14a</jats:bold>–<jats:bold>d</jats:bold> and <jats:bold>20a</jats:bold>–<jats:bold>d</jats:bold>, respectively (<jats:italic>Schemes 3</jats:italic> and <jats:italic>5</jats:italic>), with high stereoselectivity (see <jats:italic>Table</jats:italic> and <jats:italic>Scheme 6</jats:italic>). These stereospecific transformations represent the first reported examples of an acid‐mediated polyene cyclization, in which an alkene is the initiating group and an allenic alcohol serves as the internal terminator. In close analogy to our earlier work, a nonsynchronous process is postulated, whereby the stereochemical course of cyclization is directed by the conformational structure of an intermediate cyclohexyl cation (see <jats:italic>Schemes 3</jats:italic> and <jats:italic>6</jats:italic>). In addition, the organoleptic properties of <jats:bold>14c</jats:bold> and <jats:bold>20c</jats:bold>, racemic didehydro and methyl didehydro analogues, respectively, of the known odorant <jats:italic>Ambrox</jats:italic><jats:sup>®</jats:sup> ((−)‐<jats:bold>4f</jats:bold>), are briefly discussed.</jats:p>