Pummerer rearrangement trimethylsilyl triflate

Use of trimethylsilyl triflate to bring about Piunmeier rearrangement requires the presence of a base such as a tertiary amine (vide supra equations 15 and 26). In some instances, involving attempts to alkylate Pummerer intermediates with silyl enol ethers under such conditions, the base has been found to compete as a nucleophile. In the absence of the silyl enol ether, amine addition can be very efficient. For example, treatment of methallyl phenyl sulfoxide with diisopropylethylamine and trimethylsilyl inflate in dichloromethane (equation 29) at 0 C yields the ammonium triflate indicated in 91% yield. Other tertiary amines which undergo this reaction include niethylamine and Af,Af-diethyltrimethylsiI-amine. In the latter case with allyl phenyl sulfoxide as the substrate and a mildly acidic wotk-up, the Mannich derivative shown in equation (30) can be obtained in 90% yield. ... 

Electrophilic reagents capable of bringing about Pummerer rearrangement include inorganic and organic aci, carboxylic anhydrides, acyl halides, isocyanates, carbodiimides, trimethylsilyl halides and triflate, sulfonyl and sulfenyl halides, phosphorus pentoxide and many typical Lewis acids such as boron... 

---