Versatile Stereocontrol in Asymmetric Horner-Wadsworth-Emmons Resolution of a Racemic Diphenylphosphoryl-Protected a-Aminoaldehyde

Reinhard Kreuder, Tobias Rein, Oliver Reiser

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    Abstract

    In kinetic resolutions of the racemic aldehyde 1 by reaction with chiral phosphonates of type 2, all of which contain the same chiral auxiliary in the same enantiomeric form, any of the four diastereomers 3a, 3b, 4a or 4b can be obtained as the main product by an appropriate choice of reaction parameters (geometric selectivities from 66:34 to 98:2, diastereomer ratios between 93:7 and *99:1). The switch in stereoselectivity observed when KHMDS or NaHMDS is used as base instead of KHMDS/18-crown-6 is rationalized as resulting from a change in influence of the aldehyde a-stereocenter from Felkin-Anh-Eisenstein to chelation control.
    Original languageEnglish
    JournalTetrahedron Letters
    Volume38
    Issue number52
    Pages (from-to)9035-9038
    Publication statusPublished - 1997

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