Methyl sulfonium hexachloroantimonate

Methylaluminum dichloride, 7 a-Methylamino acids, 192 Methyl a-arylacetates, 268 Methyl a-arylalkanoates, 471 a-Methylbenzylamine, 411 Methyl bis(methylthio)sulfonium hexachloroantimonate, 335-336 N-Methyl-N-(t-butyldimethylsilyl)acetamide, 336... 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

Methyl(bismethylthio)sulfonium hexachloroantimonate, (CH3 8)2 SCH3 SbClg (1). Mol. wt. 475.76. 

ENYNES Diacetatobis(triphenylphosphine)paIladium(II). Tetrakis(triphenylphosphine)-palladium(O). Tetramethylethylenediamine. 1 -TrimethyIsilylpropynylcopper. EPISULFONIUM SALTS Methyl(bismethylthio)sulfonium hexachloroantimonate. EPOXIDES Bromomethyllithium. Diphenyl selenide. Methaneselenol. 

THIIRANES 3-Methylbenzothiazole-2-thione. 2-Thiomethyl-4,4-dimethyl-2-oxazoline. THIIRENIUM SALTS Methyl(bismethylthio)sulfonium hexachloroantimonate. THIOACYL CHLORIDES Hydrogen chloride. 

CH3SCH2+SbCle-] + S(CHs)2 SbClg added dropwise with Dry Ice-acetone cooling under N2 during 20 min. to a stirred soln. of dimethyl sulfide, chloromethyl methyl sulfide, and methylene chloride, stirred 1 hr. at -78°, and warmed to room temp. -> dimethyl(methyl-thiomethyl)sulfonium hexachloroantimonate. Y 92%. F. e., also with BF3, s. D.W. Hansen, Jr., and R. A. Olofson, Tetrahedron 27, 4221 (1971) cf. ibid. 27, 4209. 

A soln. of antimony pentachloride in dry methylene chloride added dropwise at 0° to a well-stirred soln. of dimethyl disulfide in the same solvent methyl-bis(methylthio)sulfonium hexachloroantimonate. Y 92%.R. Weiss and C.Schlierf, Synthesis 1976, 323. 

Scheme 5.1 Mechanism of thioglycoside activation (a) by thiophiles X1 such as /V-bromosuccinimicle (NBS), 11,12 methyl triflate,13 dimethyl(methylthio)sulfonium triflate (DMTST),14 phenylselenyl triflate (PhSeOTf),17,18 iV-iodosuccinimide/triflic acid (MS/TfOH),19 20 and iodonium di-sym-collidine perchlorate (IDCP)21 (b) by tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA,+)25 and (c) via anomeric sulfoxides.26 The stereochemical outcome of these glycosylations follows the same general trends as with many other glycosyl donor/promoter combinations (m-CPBA = mcta-chloroperbenzoic acid).

Sulfonium salts of thiepanes are readily formed by electrophilic attack of alkyl halides on the cyclic thioether. Thus, thiepane (35) was found to yield a sulfonium iodide (123), which at elevated temperatures and in the presence of excess methyl iodide underwent ring cleavage to yield 1,6-diiodohexane (isolated as the 1,6-diphenoxy derivative Scheme 24) (53M1206). The alkoxysulfonium salt (124) formed by reaction of (35) with t-butyl hypochlorite (equation 23) was characterized as a stable hexachloroantimonate (67JOC2014). Reduction of thiepane 1-oxide (115) to thiepane has been achieved using an aqueous solution of NaHSC>3 (72JOC919). A hydroxysulfonium salt intermediate (125) has been proposed in the latter reduction reaction which provides a general method for sulfoxide reductions under mild conditions (equation 24). 

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