Synlett 1991; 1991(12): 881-884
DOI: 10.1055/s-1991-20910
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An Approach to the Skeleton of Yohimbine-Type Alkaloids via Mannich-Michael Reactions with Indolylethylimines

Herbert Waldmann* , Matthias Braun, Markus Weymann, Markus Gewehr
  • *Universität Bonn, Institut für Organische Chemie and Biochemie, Gerhard-Domagk-Str. 1, D-5300 Bonn, Germany
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Publication History

Publication Date:
07 March 2002 (online)

Schiff bases derived from tryptophane methyl ester and tryptamine react with Danishefsky's diene [1-methoxy-3-(trimethylsiloxy)-1,3-butadiene] in the presence of zinc(II) chloride to give enaminones (1-[2-(indol-3-yl)ethyl]-4-oxo-1,2,3,4-tetrahydropyridines), which are subsequently transformed into indolo[2,3-a]quinolizidin-2-ones (1,2,3,4,6,7,12,12b-octahydro-2-oxoindolo[2,3-a]quinolizines) by acid-catalyzed cyclization.