[68734-62-3] · C7H9F9O3SSi · Trimethylsilyl Nonaflate · (MW 372.32)
(Lewis acid capable of generating enol silyl ethers from ketones;1 selective Friedel-Crafts catalyst for nucleoside formation from silylated heterocycles and peracylated sugars;2 catalyzes cis/trans equilibration of substituted cyclopropanes;3 used in the formation of mixed iodonium sulfonates4)
Physical Data: bp 70-72 °C/12 mmHg.5
Solubility: sol most organic solvents.
Preparative Methods: can be conveniently generated in situ by the addition of Chlorotrimethylsilane to a suspension of potassium nonaflate.1 Other methods of preparation exist;5,6 however, the aforementioned method appears to be the most efficient.
Handling, Storage, and Precautions: should be used as prepared.
It has been shown that enolizable ketones can be efficiently converted to their corresponding enol silyl ethers by the reaction of trimethylsilyl nonaflate and Triethylamine at the temperature of refluxing cyclohexane (eqs 1 and 2).1
Trimethylsilyl nonaflate as well as Trimethylsilyl Trifluoromethanesulfonate and Trimethylsilyl Perchlorate have been shown to be selective and efficient Friedel-Crafts catalysts for the formation of nucleosides from silylated heterocycles and peracylated sugars. They are also useful catalysts for the rearrangement of persilylated protected nucleosides.2 The aforementioned catalysts are more advantageous to the typically employed Tin(IV) Chloride owing to their reduced Lewis acidity.
Trimethylsilyl nonaflate is also an effective Lewis acid catalyst for the low-temperature cis/trans equilibration of methyl 2-trimethylsiloxycyclopropanecarboxylates via heterolytic cleavage of a carbon-carbon bond (eq 3).3
Mixed iodonium sulfonates of the type PhI(CN)OSO2C4F9 can be generated in a one-pot procedure by the reaction of PhIO and trimethylsilyl nonaflate followed by the addition of Cyanotrimethylsilane.4
Nicholas J. Sisti
SmithKline Beecham Pharmaceuticals, King of Prussia, PA, USA