Dimethyl sulfonium trifluoromethanesulfonate

Frejd and co-workers utilized a different tactic for aniline cyclization by first employing a Heck-Jeffery protocol under solvent-free conditions to prepare o-amino dehydrophenylalanine derivatives from o-aminoaryl iodides with the former undergoing a spontaneous la cyclization-elimination sequence to afford 2-methoxycarbonyl indoles <06S1183>. Dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST) was used by the Okuma group to promote the cyclization of o-vinyl-A-p-toluenesulfonylanilide to N-tosylindole <06CL1122>. 

Fugedi, P, Dimethyl(methylthio)sulfonium trifluoromethanesulfonate. In e-EROS, Electronic Encyclopedia of Reagents for Organic Synthesis, Paquette, L A, Ed., Wiley Interscience, New York, 2002, http //www.mrw.interscience.wiley.com/eros/eros articles fs.html. 

Abbreviations Ac acetyl AIBN azobisisobutyronitrile All allyl Bn benzyl Bz benzoyl ClAc chloroacetyl DAST diethylaminosulfur trifluoride DBU l,8-diazabicyclo[5.4.0]-undec-7-ene DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTST dimethyl(methylthio)sulfonium trifluoromethanesulfonate Fmoc 9-fluorenyl-methoxycarbonyl HDTC hydrazine dithiocarboxylate IDCP iodonium di-collidine perchlorate Lev levulinoyl MBz 4-methylbenzoyl Me methyl MEK methyl ethyl ketone MP 4-methoxyphenyl NBS iV-bromosuccinimide NIS A-iodosuccinimide Pent n-pentenyl Pfp pentafluorophenyl Ph phenyl Phth phthaloyl Piv pivaloyl PMB 4-methoxybenzyl TBAF tetrabutylammonium fluoride TBDMS tcrt-butyldimethylsilyl TBDPS tert-butyldiphenylsilyl TCA trichloroacetyl TES triethylsilyl Tf trifluoromethanesulfonyl TMS trimethylsilyl Tol 4-methylphenyl Tr trityl Troc 2,2,2-trichloroethoxycarbonyl Ts tosyl. 

Notes and discussion. Coupling reactions that exploit the methylthioglycoside of a-(2 —> 3)sialyl-galactose derivative have produced a number of sialo-oligosacchar-ides to date. For glycosylations with less reactive acceptors, activation by the action of dimethyl(methylthio)sulfonium trifluoromethanesulfonate is considered to be more feasible. Recently the corresponding trichloroacetimidate donor has also been utilized. 

DMTST Dimethyl(thiomethyl)sulfonium trifluoromethanesulfonate (triflate) Et Ethyl... 

Related Reagents. Dimethyl(methylthio)sulfonium Trifluoromethanesulfonate (DMTST) 7V-Iodosuccinimide W Iodosaccharin 1-Benzenesulfinyl Piperidine Diphenyl Sulfoxide. 

Alternate Name dimethyl(methylthio)sulfonium triflate, dime-thylthiomethyl sulfonium trifluoromethanesulfonate, DMTST. 

Addition to Double Bonds. Compared with other alkylsul-fenylating agents, addition of dimethyl(methylthio)sulfonium trifluoromethanesulfonate to double bonds is less frequently used. Treatment of olefins with the reagent followed by the addition of triphenylphosphine gave 2-methylthioalkylphosphonium salts in high yields, which could be converted into vinylphosphonium salts or vinyl phosphine oxides (eq 9). ... 

Immediately after work-up the acetals were treated with dimethyl(methylthio)-sulfonium trifluoromethanesulfonate (DMTST) in CH2CI2 to give P-o-fructofur-anoside derivatives 19, both in 11% yield. 

Pyruvate ketals can be synthesized [161] by direct condensation of a pyruvate ester with a diol in the presence of a Lewis acid, but this is less preferred because of the electron-withdrawing effect of the adjacent carboxylate group [162,163]. Therefore, several indirect methods for the acetalization have been introduced including condensation with pyruvate derivatives [164,165] or generation of the carboxylate group by oxidation of a suitable precursor [166,167,168,169]. A more efficient route to pyruvic acid acetals starts from silylated diols [170] or by the reaction between diols and methyl pyruvate dialkyl dithioacetal [171,172] activated by methyl triflate, dimethyl(methylthio)sulfonium trifluoromethane sulfonate (DMTST), nitroso tetraflu-oroborate (NOBF4), S02Cl2-trifluoromethanesulfonic acid, or Al-Iodosuccinimide (NIS) and trifluoromethanesulfonic acid [173] (O Scheme 24). 

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