New Reaction Mode of the Horner-Wadsworth-Emmons Reaction for the Preparation of α-Fluoro-α,β-unsaturated Esters

Shigeki Sano; Tsuyoshi Ando; Kenji Yokoyama; Yoshimitsu Nagao

doi:10.1055/s-1998-1780

Synlett 1998; 1998(7): 777-779
DOI: 10.1055/s-1998-1780

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New Reaction Mode of the Horner-Wadsworth-Emmons Reaction for the Preparation of α-Fluoro-α,β-unsaturated Esters

Shigeki Sano^* , Tsuyoshi Ando, Kenji Yokoyama, Yoshimitsu Nagao

^*Faculty of Pharmaceutical Sciences, The University of Tokushima, Sho-machi, Tokushima 770-8505, Japan; Fax +81-8 86-33-95 03; E-mail: ynagao@ph.tokushima-u.ac.jp

Abstract

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Excellent E-selectivity was observed in the Horner-Wadsworth-Emmons (HWE) reactions of ethyl 2-fluoro-2-diethylphosphonoacetate 1 with alkyl aryl ketones 2a-f using Sn(OSO₂CF₃)₂ and N-ethylpiperidine. Mg(II)-promoted HWE reactions of 1 with aldehydes 2h,i afforded α-fluoro-α,β-unsaturated esters 3h,i in a Z-selective manner depending on the reaction temperatures.

Horner-Wadsworth-Emmons reaction - tin - magnesium α-fluoro-α,β-unsaturated ester - alkene

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