55 New Synthetic Approach to 1-Fluorocyclopropane Derivatives

Wednesday, November 4, 2009
Ballroom A+B (Camino Real Hotel)
Timo Weide , Department of Chemistry, The Scripps Research Institute, La Jolla, CA
Benjamin Fraser , Department of Chemistry, The Scripps Research Institute, La Jolla, CA
Valery V. Fokin , Department of Chemistry, The Scripps Research Institute, La Jolla, CA

New Synthetic Approach to 1-Fluorocyclopropane Derivatives

Cyclopropane derivatives have attracted considerable attention as important pharmacophores. The conjugate addition of stabilized sulfonium ylides to a,b-unsaturated ketones and esters to give cyclopropane-1-carboxylate derivatives with high diastereo- and enantioselectivity has been extensively studied in both catalytic and stoichiometric modes. Despite these advances, preparation of functionalized 1-fluorocyclopropane-1-carboxylate derivatives remains a significant and daunting challenge.

Herein we would like to present a convenient one-pot synthesis of fluorocyclopropanes wherein the cyclopropane moiety is assembled using by a modified conjugate addition with a fluorinated sulfonium ylide. The cyclopropanation is achieved using an novel fluoro-substituted ethyl-(dimethylsulfuranylidene)-acetate generated in situ from the corresponding ylide and a fluorinating reagent in THF at -78C.

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