Chromium(II) chloride-promoted reductive β-elimination of 1,1-dihalo alditols. Synthesis of highly functionalized alk-1-enyl halides

A new general synthetic route to obtain highly functionalized (Z)- and (F)-alk-1-enyl halides is described, where the halogen can be indistinctly F, Cl, Br, and I. The procedure involves Crcl(2)-promoted reductive elimination of beta-O-substituted gem-dihalo alditols easily accessible from carbohydrates. The simplicity and mildness of the reaction conditions and their compatibility with different functional groups increase the synthetic potential of this methodology. (C) 2008 Elsevier Ltd. All rights reserved.