Trimethylsilyl chlorosulfonate

By an interesting reaction involving trimethylsilyl chlorosulfonate and hexamethyldisilane, two methanesulfonates containing the silicon-silicon bond have recently been prepared (13). 

Both pyrrole and furan can be sulfonated with the pyridinesulfur trioxide complex. The pyrrole product is now known to be the 3-sulfonic acid (Scheme 25) <2000TL6605>. The reaction of l-methyl-2-tri- -butylstannylpyrrole with trimethylsilyl chlorosulfonate, followed by quenching with aqueous NaHC03 generates sodium l-methylpyrrole-3-sulfonate. Furan-2-sulfonic acid can be further sulfonated with pyridineS03 to give the 2,5-disulfonate. 

Adducts of iodosylbenzene with sulfur trioxide (183 and 185) (Section 2.1.7) react with alkenes under mild conditions to give the respective cyclic sulfate esters, such as 184,186 and 187 (Scheme 3.78) [218, 244]. Likewise, phenyliodine(in) sulfate 185, generated from iodosylbenzene and trimethylsilyl chlorosulfonate... 

Figure 2.7 shows the different steps of the synthesis procedure. The commercial polysulfone Udel (Amoco) was dissolved in chloroform at a temperature of 25 °C and subsequently treated with trimethylsilyl chlorosulfonate (Aldrich) to produce a silyl sulfonate polysulfone. The amount of the intermediate product was cmitrolled by the molar ratio of the sulfonating agent to the polymer repeating unit and varied from 2 to 2.3. The reaction time was 24 h at a temperature of 25 0.1 °C. The obtained silyl sulfonate polysulfone polymer was then treated with a 30 wt% sodium methoxide/ methanol solution (2.26 mmol g of polysulfone) at 25 °C for 1 h, which was used to cleave the sUyl sulfraiate moieties, yielding the sodium... 

An equimolar mixture of hexamelhyldisiloxane and trimethylsilyl chlorosulfonate refluxed several hrs. after the initial exothermic reaction has subsided bis (trimethylsilyl) sulfate (Y 94.5%) and trimethylchlorosilane (Y 93.4%).—Silyl chlorosulfonates are highly reactive compounds and very strong sulfating agents. F. e. s. M. Schmidt and H. Schmidbaur, B. 9A, 2446 (1961). 

Propargylic Anion Equivalent. (TMS)allene reacts with electrophiles at the C-3 position in an Se2 process analogous to electrophilic substitution reactions of allyl- andpropargylsilanes. For example, upon treatment with trimethylsilyl chlorosulfonate or sulfur trioxide-1,4-dioxane, (TMS)allene yields silyl esters of sulfonic acids (eq 3). (TMS)allene undergoes conjugate addition with a, 8-unsaturated acyl cyanides to yield 5,e-acetylenic acyl cyanides. ... 

Polysulfone (PSU, Fig, 11,4) is an interesting polymer for its low cost, commercial processability and availability. Two different procedures for the sulfonation of polysulfone are reported. In the first, a sodium-sulfonated group is intfoduced in the base polysulfone via the metalation-sulfination-oxidation process [90], and in the other, the trimethylsilyl chlorosulfonate is used as the sulfonating agent. However, following either of these two procedures, the result remains the same The proton conductivity of the sulfonated PSU membrane is lower than Nafion membrane, because the C-F chains in Nafion have high hydrophobicity and large-phase separation. 

Chlorosulfonic acid reacts with tetramethylsilane 458 to give trimethylsilyl chlorosulfonate 459 (Equation 143). ... 

Trimethylsilyl chlorosulfonate 459 is useful as a mild sulfonating agent and it reacts with a range of organic compounds containing the trimethylsilyl group as illustrated by Equations 144-146. " It was by this synthetic route that cyclopropanesulfonic acid 460 was first prepared (Equation 145). The general mechanism of these reactions is depicted in Scheme 14. 

The mechanism involves initial nucleophilic attack by the trimethylsilyl compound on the electrophilic sulfur atom of trimethylsilyl chlorosulfonate 459 with loss of trimethylsilyl chloride. In the second step, the initially formed trimethylsilyl sulfonate is hydrolysed to the corresponding sulfonic acid (Scheme 14). Chlorosulfonic acid reacts as a nucleophile with certain trimethylsilylmethyl compounds with regioselective cleavage of the silicon-carbon (sp hybridized) bond. For instance, trimethylsilylmethyl chloride 461 with chlorosulfonic acid afforded the compound 462, which on heating gave the compounds 463-465 (Scheme 15). °... 

The reaction involves initial insertion of sulfur trioxide into the nitrogen-silicon bond of anilinotrimethylsilane 466 the sulfamic acid 467 was, however, contaminated with small amounts of anilinium salts. It was discovered that the reaction of anilinotrimethylsilane 466 with trimethylsilyl chlorosulfonate 459 gave improved yields of the pure sulfamic acid 467. Trimethylsilyl chlorosulfonate 459 will effect the sulfosilation of aromatic hydrocarbons to give the trimethylsilyl arenesulfonates 468 (Equation 148). 

An improved simple synthesis of cyclic sulfates from trimethylsilyl chlorosulfonate 291... 

An Improved Simple Synthesis of Cyclic Sulfates from Trimethylsilyl Chlorosulfonate... 

Trimethylsilyl chlorosulfonate can be prepared by reaction of tetramethylsilane with chlorosulfonic acid (Chapter 4, Section 12.8). The reaction of trimethylsilyl chlorosulfonate (21) with iodosobenzene (22) in dichloromethane at —78°C under nitrogen, followed by warming to RT, removal of solvent and trimethylsilyl chloride, yields phenyliodosulfate (23) (Equation 3). Phenyliodosulfate, without further purification, reacts with alkenes to give cyclic sulfates (24, 50-76% yield) (Equation 4). 

Sulfonation of the aromatic ring of l, 2, 2 -trifluorostyrene below 0 C does not give satisfactory yields with chlorosulfonic acid or a sulfur trioxide-dioxane complex Tar forms on heating In contrast, under similar conditions ipso substitution IS facile at the position of a trialkylsilyl or -stannyl group Thus, 4-trimethyl-silyl-T 2, 2 D-trifluorostyrene affords the corresponding trimethylsilyl sulfonate [20] (equation 9)... 

---