Trimethyloxonium tetrafluoroborate, 96%, Thermo Scientific Chemicals

General References:

1. Trialkyloxonium salts, also known as Meerwein's salts, are powerful alkylating agents under mild conditions. For general reactions of trialkyloxonium salts, see Triethyl oxonium tetrafluoroborate, A14420 . For a brief feature of their uses in synthesis, see: Synlett, 195 (2004).
2. Alkylation of ethylene thioacetals proceeds only to the monoalkyl salt unless water is added, when the thioacetal is cleaved to give the carbonyl compound and the tetraalkyl ethane bis-sulfonium salt: Synthesis, 135 (1981). Alkylation on S to promote leaving group ability has also been used in a synthesis of oxiranes from ß-hydroxy sulfides: J. Am. Chem. Soc., 95, 3429 (1973); J. Chem. Soc., Chem. Commun., 714 (1975).
3. N,N-Dialkyl arylcarboxamides, useful as substrates for directed metallation reactions, can be converted to methyl esters in high yield: Tetrahedron, 56, 9875 (2000).
4. Nortcliffe, A.; Moody, C. J. Seven-membered ring scaffolds for drug discovery: Access to functionalised azepanes and oxepanes through diazocarbonyl chemistry. Bioorg. Med. Chem. 2015, 23 (11), 2730-2735.
5. Lim, J. Y.; Cunningham, M. J.; Davis, J. J.; Beer, P. D. Halogen bonding-enhanced electrochemical halide anion sensing by redox-active ferrocene receptors. Chem. Commun. 2015, 51 (78), 14640-14643.