Iodotrimethylsilane

Oxiranes react with iodotrimethylsilane to give silylated halo alcohols e.g. 60) which can be converted to allylic alcohols (Scheme 53) (80JOC2579, 80TL2329) cf. other syntheses of allylic alcohols (Sections 5.05.3.2.2, 5.05.3.4.3(0 and Hi)). 

Boron tribromide is reported to be more effective than iodotrimethylsilane for cleaving aryl methyl ethers. ... 

Trimethylsilyl l//-azepine-f-carboxylate (4), prepared in 71 % yield by treating methyl 17/-azepine-1 -carboxylate with iodotrimethylsilane in chloroform at 20°C, with methanol in pentane solution at — 78 °C undergoes slow hydrolysis to the bright-yellow 17/-azepine-l-carboxylic acid (5),9 which is also obtained, as the potassium salt, by the action of potassium /ert-butoxide on ethyl 17/-azepine-l-carboxylate.139 The acid is stable at —78°C for several days but in chloroform solution at 20 °C undergoes decarboxylation to 17/-azepine (6) accompanied by some decomposition. 17/-Azepine is stable for a few hours at — 78 C and has been characterized by 3H and l3CNMR spectroscopy. 

Likewise, synthetic 2//-azepines isomerize to 3//-azepines in refluxing chloroform (2-3 h) or in tert-butyl methyl ether at room temperature.291 The isomers can be readily separated by chromatography on silica gel, as the more basic 2//-azepines30 have lower Rf values. In contrast, 7-butyl-2//-azepin-2-acetic acid (11), obtained by heating the tert-butyl ester 10 with iodotrimethylsilane, is stabilized by intramolecular hydrogen bonding and shows no tendency to rearrange to the 3//-isomer.291... 

If no aqueous workup, but anhydrous cleavage of the reaction product 11 is performed with iodotrimethylsilane, the titanium iodide 12 can be recovered or used again in the same flask36. 

Benzyloxy-2-propenylchromium reagents are formed by the action of iodotrimethylsilane and chromium(II) chloride on 3,3-bis(benzyloxy)-l-propene in the presence of aldehydes, affording derivatives of anti-diols with good diastereoselectivity13. 

THF THP TIPS TIPSOTf TMEDA TMS TMSC1 TMSCN TMS I TMSOTf Ts tetrahydrofuran tetrahydropyranyl tri-isopropylsilyl tri-isopropylsilyl trifluoromethanesulphonate AVV,N N -tetramethylethylenediamine trimethylsilyl trimethylsilyl chloride (chlorotrimethylsilane) trimethylsilyl cyanide (cyanotrimethylsilane) trimethylsilyl iodide (iodotrimethylsilane) trimethylsilyl trifluoromethanesulphonate tosyl (p-tolucnesulphonyl)... 

The structurally simplest silicon reagent that has been used to reduce sulphoxides is the carbene analog, dimethylsilylene (Me2Si )29. This molecule was used as a mechanistic probe and did not appear to be useful synthetically. Other silanes that have been used to reduce sulphoxides include iodotrimethylsilane, which is selective but unstable, and chlorotrimethylsilane in the presence of sodium iodide, which is easy to use, but is unselective since it cleaves esters, lactones and ethers it also converts alcohols into iodides. To circumvent these complications, Olah30 has developed the use of methyltrichlorosilane, again in the presence of sodium iodide, in dry acetonitrile (equation 8). A standard range of sulphoxides was reduced under mild conditions, with yields between 80 and 95% and with a simple workup process. The mechanism for the reaction is probably very similar to that given in equation (6), if the tricoordinate boron atoms in this reaction scheme are replaced... 

Dialkyl and alkyl aryl ethers can be cleaved with iodotrimethylsilane ROR -bMe3SiI — Rl-bMe3SiOR. A more convenient and less exjjensive alternative, which gives the same products, is a mixture of chlorotrimethylsilane and Nal. Alkyl aryl ethers can also be cleaved with Lil to give alkyl iodides and salts of phenols in a reaction similar to 10-73. Triphenyldibromophosphorane (Ph3PBr2) cleaves dialkyl ethers to give 2mol of alkyl bromide. ... 

Pyridine is added to neutralize small amounts of hydrogen iodide, which is often present in iodotrimethylsilane as a result of hydrolysis by contact with moisture. The amount of by-products, including cyclohexyl iodide, is reduced by the presence of pyridine. Hindered pyridine bases such as 2,6-di-terf-butyl-4-methylpyridine" have also been used for this purpose by the submitters. The pyridine bases do not appear to react with iodotrimethylsilane. 

When an insufficient amount of iodotrimethylsilane was used by the submitters, cyclohexyl methyl ether remained at the end of the reaction and was eluted from the silica gel column before cyclohexanol. When present in the crude product, cyclohexyl iodide was also eluted from the column before cyclohexanol. 

Alkyl esters are efficiently dealkylated to trimethylsilyl esters with high concentrations of iodotrimethylsilane either in chloroform or sulfolane solutions at 25-80° or without solvent at 100-110°.Hydrolysis of the trimethylsilyl esters serves to release the carboxylic acid. Amines may be recovered from O-methyl, O-ethyl, and O-benzyl carbamates after reaction with iodotrimethylsilane in chloroform or sulfolane at 50—60° and subsequent methanolysis. The conversion of dimethyl, diethyl, and ethylene acetals and ketals to the parent aldehydes and ketones under aprotic conditions has been accomplished with this reagent. The reactions of alcohols (or the corresponding trimethylsilyl ethers) and aldehydes with iodotrimethylsilane give alkyl iodides and a-iodosilyl ethers,respectively. lodomethyl methyl ether is obtained from cleavage of dimethoxymethane with iodotrimethylsilane. 

The use of iodotrimethylsilane for this purpose provides an effective alternative to known methods. Thus the reaction of primary and secondary methyl ethers with iodotrimethylsilane in chloroform or acetonitrile at 25—60° for 2—64 hours affords the corresponding trimethylsilyl ethers in high yield. The alcohols may be liberated from the trimethylsilyl ethers by methanolysis. The mechanism of the ether cleavage is presumed to involve initial formation of a trimethylsilyl oxonium ion which is converted to the silyl ether by nucleophilic attack of iodide at the methyl group. tert-Butyl, trityl, and benzyl ethers of primary and secondary alcohols are rapidly converted to trimethylsilyl ethers by the action of iodotrimethylsilane, probably via heterolysis of silyl oxonium ion intermediates. The cleavage of aryl methyl ethers to aryl trimethylsilyl ethers may also be effected more slowly by reaction with iodotrimethylsilane at 25—50° in chloroform or sulfolane for 12-125 hours, with iodotrimethylsilane at 100—110° in the absence of solvent, " and with iodotrimethylsilane generated in situ from iodine and trimcthylphenylsilane at 100°. ... 

Acenaphthylene, 58, 73 Acetaldehyde, 58, 157 Acetals, cleavage with iodotrimethylsilane, 59, 40... 

The selective and facile cleavage of the benzylic ether linkages of 1,2,3 or 4 is accomplished by treatment with iodotrimethylsilane to form the corresponding benzylic iodide. Further addition to these iodide derivatives of 1 affords dendrimers of generation 1 with phosphonium ion sites at the periphery. Such a strategy is conducted up to generation 3 with a phosphine or a phosphonium core (Scheme 3). 

Iodotrimethylsilane generated in situ from chlorotrimetylsilane and sodium iodide effects the reduction of nitroalkenes into ketones at 0 °C. This method is useful for the conversion of nitro steroids or nitro terpenoids to the corresponding ketones (Eq. 6.24).43... 

Iodotrimethylsilane formed in situ from the reaction of chlorotrimethylsilane and sodium iodide, also effects the conversion of 2-ene-l,4-diols to 1,3-dienes (equation 16)46. Allylic thionocarbonates on heating with triphenylphosphite undergo deoxygenation (Corey-Winter reaction) to generate olefins47. This procedure has been used for making hexatrienes (equation 17)47b. 

To 2,3-dioleoyloxy-l-iodopropane (3.65 g, 5 mmol) was added tris(tri-methylsilyl) phosphite (15.05 g, 50 mmol), along with a trace of butyl hydrogen phthalate. The reaction mixture was stirred under a static nitrogen atmosphere with heating at 125°C for 16 h. After this time, excess tris(trimethylsilyl) phosphite and iodotrimethylsilane were removed by high vacuum distillation (bath 100°C) to leave a colorless oil. The residue was dissolved in THF water (9 1, 50 ml) and allowed to stand in the dark at room temperature for 12 h. The solvent was... 

The reagent is similar to iodotrimethylsilane in reactivity. It also converts alcohols into iodides, but in contrast to ISi(CH,)j, it reacts more rapidly with secondary alcohols (with inversion) than with primary ones. It also cleaves ethers, and again it cleaves secondary alkyl ethers more readily than primary alkyl ethers. 

As with other non-metal derivatives, reactivity depends on chain-length, branching and degree of halogen substitution. Individually indexed compounds are f Chloromethylphenylsilane, 2810 f Chlorotrimethylsilane, 1304 f Cyanotrimethylsilane, 1665 f Dichlorodiethylsilane, 1683 f Dichlorodimethylsilane, 0902 f Dichloroethylsilane, 0903 f Dichloromethylsilane, 0470 f Dichloromethylvinylsilane, 1208 f Iodotrimethylsilane, 1306 f Methyltrichlorosilane, 0439 f Trichloroethylsilane, 0854 f Trichlorovinylsilane, 0746... 

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