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Über Umwandlungen der Iboga‐Alkaloide Voacangin und Conopharyngin 154. Mitteilung über Alkaloide
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Titel: |
Über Umwandlungen der Iboga‐Alkaloide Voacangin und Conopharyngin 154. Mitteilung über Alkaloide |
In: | Helvetica Chimica Acta, 58, 1975, 1, S. 211-230 |
veröffentlicht: |
Wiley
|
Umfang: | 211-230 |
ISSN: |
0018-019X 1522-2675 |
DOI: | 10.1002/hlca.19750580130 |
Zusammenfassung: | <jats:title>Abstract</jats:title><jats:p>The reduction products voacanginol (<jats:bold>3</jats:bold>) and conopharynginol (<jats:bold>4</jats:bold>), obtained from the indole alkaloids voacangine (<jats:bold>1</jats:bold>) and conopharyngine (<jats:bold>2</jats:bold>) respectively, gave, by the treatment of their tosylates <jats:bold>5</jats:bold> und <jats:bold>6</jats:bold> with triethylamine, two fragmentation products, voaenamine (<jats:bold>7</jats:bold>) (70–80%) and conoenamine (<jats:bold>8</jats:bold>) (25–45%) respectively (<jats:italic>Scheme 1</jats:italic>). The structures of <jats:bold>7</jats:bold> and <jats:bold>8</jats:bold> were derived from spectroscopic evidence and some chemical transformations.</jats:p><jats:p>Conopharynginol tosylate (<jats:bold>6</jats:bold>) gave with tertiary base, besides <jats:bold>8</jats:bold>, the quaternary aziridinium salt <jats:bold>12</jats:bold> (58%) (<jats:italic>Scheme 3</jats:italic>). This salt could undergo nucleophilic attack, giving compounds of the A‐series with a C‐homo‐conopharyngine skeleton (due to attack at C(<jats:bold>18</jats:bold>)) and compounds of the B‐series with a spiro‐centre (due to attack at carbon(5)) (<jats:italic>Scheme 3</jats:italic>). The structures of these compounds were elucidated using D‐incorporation experiments, <jats:sup>1</jats:sup>H‐ and <jats:sup>13</jats:sup>C‐NMR. and mass spectra. On heating to 230°, acetylated spiroalcohol <jats:bold>22</jats:bold> was converted, probably <jats:italic>via</jats:italic> the ion pair <jats:bold>23</jats:bold>, into the base <jats:bold>16</jats:bold>, which on catalytic reduction gave <jats:bold>13</jats:bold>, a member of the A‐series.</jats:p><jats:p>The reactions mentioned above constitute interesting skeletal isomerisations of the conopharyngine skeleton.</jats:p> |
Format: | E-Article |
Quelle: | Wiley (CrossRef) |
Sprache: | Englisch |