2- -3-methyl-5-methylthio- tetrafluoroborate

The synthesis of a-methylthionitriles in high yield by cyanosulfenylation , i.e. addition of di-methyl(methylthio)sulfonium tetrafluoroborate to alkenes, followed by reaction with a CN donator, e.g. alkali metal cyanide/HBp4 or TMS-CN (equation 15), was recently described by TrostJ ... 

Cis- and fra s-di-/-butylthiiranium tetrafluoroborates (14) and (15) were generated from cis- and tra .v-di-/-butylcthylcnc respectively (Scheme 7), on reaction with methyl-bis(methylthio)sulfonium tetrafluoroborate in liquid SO2 at —78 °C. Then reaction with water was studied and different reaction modes were found.32... 

The ring-opening reaction on 4-methyl-2-thia-7-aza-tricyclo[5.3.0.01,4]decan-8-one 39 was carried out by treatment with dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) <20010L1781, 2004JOG33>. Methylthiolation of the thietane sulfur produces a transient alkylthiosulfonium salt which easily dissociates to the iV-acyliminium ion 40. Once formed, 40 readily undergoes loss of a proton to give the product 40 (Equation 11). 

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. 

In the same program, phenyldiazonium tetrafluoroborate was allowed to react with two molecules of a nitrile (RCN) at 20°-50°C to obtain 2,4-disubstituted (phenyl or benzyl) quinazolines in good yields. The nitrilium salt 58 was thought to be the first stage 41,42 Somewhat similarly, phenyldiazonium tetrafluoroborate reacted with methyl isothiocyanate to give 2,4-di(methylthio)quinazoline.41... 

Alkylation of 1,4-benzothiazepin-5(4//)-one (82) with methyl iodide/silver tetrafluoroborate gave the sulfonium salt, which rearranged to l-methoxy-4-(methylthio)isoquinoline (83) on heating in acetonitrile (Scheme 27) <88CB2147>. 

Albery et al. [39, 49] prepared poly(3-thiopheneacetic acid) and its copolymer with thiophene by electrochemical polymerization. Bartlett et al. [50] electrochemically synthesized conducting poly(3-thiophene-acetic acid) films in dry acetonitrile containing tetraethyl ammonium tetrafluoroborate. These films are redox active in acetonitrile, however, stability was reportedly poor in comparison with poly(3-methylthio-phene) and poly(methyl 3-thiopheneacetate) due to traces of water. In dry acetonitrile, the polymer can be electrochemically oxidized and reduced. Upon oxidation in water and methanol, poly(3-thiopheneacetic acid) film converted into a passive film. Based on the electrochemistry and an FT-IR study, Bartlett et al. postulate the mechanism for the electrochemical passivation shown in the Figure 4.33. In the mechanism, passivation of the polymer involves the formation of an intermediate cyclic lactone and subsequent breakdown by reaction with solvent. This process does not destroy the conductivity of the polymer so the process can continue until all the monomer units within the film are converted to a lactone form (Figure 4.33, IV). The electrochemical passivation is not observed... 

Equilibration of A -methyl-2-pyridinethione (XII-74S) with 2-methylthio-pyridine in the presence of y/-methyl-2-methylthiopyridinium tetrafluoroborate showed that the thioether is the more stable in the liquid phase [/iTeq. 14.4 (188 ), 10.7(145°)]. ... 

Related Reagents. Methyl Iodide Methyl Sulfate 1-Benzene-sulfinyl Piperidine Diphenyl Sulfoxide Dimethyl(methylthio) Sulfonium Tetrafluoroborate. 

Lithium tetrafluoroborate in wet acetonitrile has been described as an effective combination for the hydrolysis of acetals under mild weakly acidic conditions. Dithians were unaffected. Methods for the hydrolysis of thioacetals continue to appear. Reagents that have been described include a polystyryl-mercury(n) trifluoroacetate combination, which retains the metal on the resin, lead(iv) dioxide and boron trifluoride etherate, aqueous hydrochloric acid in dioxan containing dimethyl sulphoxide, methyl-bis(methylthio)sulphonium hexa-chloroantimonate, and iodoxybenzene, catalysed by toluene-p-sulphonic acid. Dithioacetals derived from ethane-1,2-dithiol may be cleaved with dimethyl sulphoxide in combination with either t-butyl or trimethylsilyl bromides and iodides. Regeneration of ketones from ethanediyl-S S -acetals via the lithium-di-isopropylamide-promoted fragmentation to the thioketone and subsequent hydrolytic work-up only gives satisfactory yields for aryl methylketone derivatives. Dithioacetal SS-dioxides are rapidly cleaved in hot methanolic hydrochloric acid solution. ... 

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