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Paper | Special issue | Vol 95, No. 2, 2017, pp.1106-1120
Published online, 16th February, 2017
DOI: 10.3987/COM-16-S(S)82
Toward the Synthesis of (‒)-Codeine by Chiral Auxiliary-Mediated Nitrone Cycloaddition

Julia Rautschek and Peter Metz*

*Department of Chemistry, Organic Chemistry I, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany

Abstract

Application of a C2-symmetric dioxolane moiety as chiral auxiliary for an asymmetric intramolecular nitrone cycloaddition was studied as a possible key step for the enantioselective synthesis of (–)-codeine. A cycloaddition precursor bearing a 1,2-diphenylethylene acetal was selected that was readily accessible in ten steps from isovanillin. It underwent nitrone cycloaddition and after a consecutive transformation, an isoxazolidine intermediate with the absolute and relative configuration required for (–)-codeine was obtained.