کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5219703 | 1383365 | 2012 | 6 صفحه PDF | دانلود رایگان |
We describe a biomimetic approach to (Z)-β-fluoroallyl alcohols based on the two carbon homologation of aromatic aldehydes to α-fluorocinnamic thioesters by Horner–Wadsworth–Emmons reaction with 2-(diethoxyphosphinyl)-2-fluoro-ethanethioic acid, S-ethyl ester, followed by reduction with sodium borohydride in mild conditions. The α-fluorothioesters were obtained in a good yield by condensing the aldehydes with the lithium anion of 2-(diethoxyphosphinyl)-2-fluoro-ethanethioic acid, S-ethyl ester in THF at −78 °C. The (E,Z)-α-fluorocinnamic thioester mixtures were then cleanly reduced with double bond isomerisation to the corresponding (Z)-β-fluoroallyl alcohols by NaBH4 at room temperature. This methodology may be applied to highly functionalized aldehydes as exemplified by the straightforward access to (Z)-β-fluoroconiferin, a strong inhibitor of lignin polymerization from O-glucosylated vanillin.
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Journal: Tetrahedron - Volume 68, Issue 15, 15 April 2012, Pages 3225–3230