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Stereoselective Preparation of (E)- and (Z)-α-Fluorostilbenes via Palladium-Catalyzed Cross-Coupling Reaction of High E/Z Ratio and (Z)-1-Bromo-1-fluoroalkenes

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journal contribution
posted on 2006-05-12, 00:00 authored by Jianjun Xu, Donald J. Burton
A highly stereoselective method to prepare both (E)- and (Z)-α-fluorostilbenes is described. 1-Bromo-1-fluoroalkenes (E/Z ≈ 1:1), a readily available starting material, isomerizes to high E/Z ratios by storage at −20 °C or by photolysis at 254 nm. Stille coupling between these high E/Z 1-bromo-1-fluoroalkenes and aryl stannanes gave (Z)-α-fluorostilbenes in high stereoselectivity. (Z)-1-Bromo-1-fluoroalkenes, which were kinetically separated from 1-bromo-1-fluoroalkenes (E/Z ≈ 1:1), can participate in Suzuki coupling reactions to give (E)-α-fluorostilbenes stereoselectively.

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