Synthesis 1989; 1989(2): 109-113
DOI: 10.1055/s-1989-27164
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Indoliziniumsalze und Heteroanaloga durch Anellierung heterocyclischer α-Methylimine mit 3-Alkoxyacroleinen

Roswitha Böhme* , Klaus Rotscheidt, Eberhard Breitmaier
  • *Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Str. 1, D-5300 Bonn 1, Federal Republic of Germany
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Publikationsdatum:
17. September 2002 (online)

Indolizinium Salts and Heteroanalogues by Annulation of Heterocyclic α-Methylimines with 3-Alkoxyacroleins Lithiated 2-Methyl-Δ1-pyrroline(1), 2-methyl-2-oxazoline(2), 2-methyl-2-thiazoline(3), and 1,2-dimethylimidazole (4) add to 3-alkoxyacroleins 5 to yield 3-alkyl-4-ethoxy-3-buten-2-ols 6, 7, 8, and 9 substituted by the starting heterocycles. These intermediates undergo cyclization with hydroiodic acid to afford dihydroindolizinium-, dihydrooxazolo[3,2-a]pyridinium-, dihydrothiazolo[3,2-a]pyridinium-, and imidazol[1,2-a]pyridinium iodides 10, 11, 12, and 14 in moderate to good yields. Thus a pyridinium ring is annulated on to a five-membered nitrogen heterocycle. 1H-NMR and 13C-NMR assignments are tabulated.