Insight into the Reactions of Trifluorovinylsilanes with Aromatic Aldehydes

The conditions for the selective addition of trialkyl(trifluorovinyl)silanes to the C=O bond of aromatic aldehydes in the presence of cesium fluoride to give the corresponding“silylated” alcohols in high yields was performed. The reactivity of the “silylated” alcohols in the presence of nucleophilic reagents and Brönsted acids was studied. On the basis of isolated compounds and of intermediates detected by NMR spectroscopic methods, several reaction pathways are proposed. Significant differences between the reaction behaviour of triethyl(trifluorovinyl)silane and trimethyl(trifluoromethyl)silane under comparable conditions are pointed out; the differences can be attributed to the highly reactive trifluorovinyl group. The reactions of the “silylated” alcohols proceed with high stereoselectivity to give propenes, acid fluorides and acids of the ( E ) isomers in better than 98 % purity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)