DMTST 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>. 

Resin bound monosaccharide 5 was glycosylated with pivaloate donor 6a in the presence of dimethyl(methylthio)trifluoromethanesulfonate (DMTST, Fig. 6). 

Silver trifluoromethanesulfonate, methylsilyl trifluoromethanesulfonate, dime-thylmethylthiosulfonium-trifluoromethane sulfonate (DMTST), and boron trifluoride diethyl etherate were obtained from Sigma-Aldrich. 

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. 

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). 

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. 

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. 

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