Iodides trimethylsilyl

The Pd(0)-catalyzed addition of trimethylsilyl iodide to an alkyne, followed by capture with alkynylstannane, affords the stereo-defined enyne 186. The reaction is explained by the oxidative addition of iodosilane, the insertion of an alkyne to generate the vinylpalladium 185, and the capture of 185 with the alkynylstannane 184[102]. 

The chlorosilanes are clear Hquids that should be treated as strong acids. They react readily with water to form corrosive HCl gas and Hquid. Liquid chlorosilanes and their vapors are corrosive to the skin and extremely irritating to the mucous membranes of the eyes, nose, and throat. The nitrogen-functional silanes react with water to form ammonia, amines, or amides. Because ammonia and amines are moderately corrosive to the skin and very irritating to the eyes, nose, and throat, silylamines should be handled like organic amines. Trimethylsilyl trifluoromethanesulfonate and trimethylsilyl iodide form very corrosive acidic products. 

Trimethylsilyl iodide [16029-98-4] (TMSI) is an effective reagent for cleaving esters and ethers. The reaction of hexamethyldisilane [1450-14-2] with iodine gives quantitative conversion to TMSI. A simple mixture of trimethylchlorosilane and sodium iodide can be used in a similar way to cleave esters and ethers (8), giving silylated acids or alcohols that can be Hberated by reaction with water. 

JUNG OLAH - VORONKOV Etherdeavage Cleavage of ethers or esters, carbamates, phosphorates with trimethylsilyl Iodides. Oeoxygenation of sulfoxides. 

Me3SiCH2CH=CH2i TsOH, CH3CN, 70-80°, 1-2 h, 90-95% yield. This silylating reagent is stable to moisture. Allylsilanes can be used to protect alcohols, phenols, and carboxylic acids there is no reaction with thiophenol except when CF3S03H is used as a catalyst. The method is also applicable to the formation of r-butyldimethylsilyl derivatives the silyl ether of cyclohexanol was prepared in 95% yield from allyl-/-butyldi-methylsilane. Iodine, bromine, trimethylsilyl bromide, and trimethylsilyl iodide have also been used as catalysts. Nafion-H has been shown to be an effective catalyst. 

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)... 

Other thietane derivatives have been obtained by isomerization of nitrogen-containing heterocycles. The reaction of an acyl isothiocyanate (RCONCS) with diphenyldiazomethane gave 20 and this isomerized in solution to the tetraphenyl-3-thietanone 21 <96BSB253>. Additionally, the isoxazolidine 22 was converted into 23 by the action of trimethylsilyl iodide and zinc iodide <96H1211>. 

N-Acetals such as 429 react with silylated amines such as 294 at ambient temperature or on gentle heating in the presence of trimethylsilyl iodide 17 in diethyl ether to afford, e.g., the N,N-acetal 453 in 88% yield and HMDSO 7 [53]. The silylated tetrazole 454 reacts on heating to 160 °C with the 0,N-acetal 422 to... 

With trimethylsilyl iodide 17 the 0,N-acetal 457 gives the iminium iodide as reactive intermediate this converts the enol silyl ether 107 a in situ into the Man-nich-base 669, in 81% yield, and hexamethyldisiloxane 7 [195]. On treatment of the 0,N-acetal 473 (or the N-silylated Schiff base 489) with TMSOTf 20 (or Zny, the intermediate iminium triflate adds to the ketene acetal 663 to give mefhoxytri-methylsilane 13 a and silylated / -amino esters such as 670, which are readily transsilylated by methanol to give the free / -aminoester [70, 196] (Scheme 5.61). 

Trimethylsilyl iodide 17, which can be generated in situ by reaction of trimethyl-silyl chloride (TCS) 14 with Nal in acetonitrile [1], converts alcohols 11, in high yields at room temperature, into their iodides 773a, HI, and hexamethyldisiloxane (HMDSO) 7 [1-8, 12]. Likewise esters such as benzyl benzoate are cleaved by Me3SiCl 14/NaI in acetonitrile under reflux [Ij. Reactions of alcohols 11 with trimethylsilyl bromide 16 in chloroform or, for in situ synthesis of 16 from liBr and TCS 14 in acetonitrile and with HMDS 2 and pyridinium bromide perbromide, proceed only on heating in acetonitrile or chloroform to give the bromides 773 b in nearly quantitative yield [3, 8, 12] (Scheme 6.1). 

Dioxane reacts with trimethylsilyl iodide 17 to give 96% 1,2-bis-iodoethane, 53% l,2-bis(trimethylsilyloxy)ethane, and 32% HMDSO 7 ]5, 29]. 1,3-Dioxolane 840 furnishes, via 841, iodomethyl-2-iodoethyl ether 842 and HMDSO 7 ]5, 30] (Scheme 6.13). 2-Substituted 1,3-dioxolanes 843 are converted by trimethylsilyl iodide 17, via a series of postulated intermediates, into 1,2-diiodoethane, the ester 844, the alkyl iodide 845, and HMDSO 7 [5] (cf also Chapter 5, Scheme 5.67). 

Reactions of sulfoxides containing a- and /9-hydrogen atoms, for example n-dibutyl sulfoxide 1170, with trimethylsilyl iodide 17 in the presence of tertiary amines such as diisopropylethylamine (DIPEA) give, e.g., the vinylsulfide 1171 as an 1 1 E/Z mixture in 75% yield and HMDSO 7 [16] (Scheme 8.4). Analogously, the vinyl sulfoxide 1172 or the vinyl sulfoxide 1174 furnish the 1,3-dienyl sulfides 1173 and 1175 in 91 and 85% yield, respectively, and HMDSO 7 [16]. 

Reductions with Trimethylsilyl Iodide, Trimethylsilyl Azide, and Trimethylsilyl Cyanide... 

Trimethylsilyl iodide (TMSI) cleaves methyl ethers in a period of a few hours at room temperature.89 Benzyl and f-butyl systems are cleaved very rapidly, whereas secondary systems require longer times. The reaction presumably proceeds via an initially formed silyl oxonium ion. 

The direction of cleavage in unsymmetrical ethers is determined by the relative ease of O-R bond breaking by either SN2 (methyl, benzyl) or SW1 (r-butyl) processes. As trimethylsilyl iodide is rather expensive, alternative procedures that generate the reagent in situ have been devised. 

Tandem syn addition of alkyl and trimethylsilyl groups can be accomplished with dialkylzinc and trimethylsilyl iodide in the presence of a Pd(0) catalyst.79... 

Both ketals100 and enol ethers101 can be used as electrophiles in place of aldehydes with appropriate catalysts. Trimethylsilyl iodide can be used in catalytic quantities... 

Our requirements for certain applications called for the preparation of block copolymers of styrene and alkali metal methacrylates with molecular weights of about 20,000 and methacrylate contents of about 10 mol%. In this report we describe the preparation and reactions of S-b-MM and S-b-tBM. In the course of our investigation, we have found several new methods for the conversion of alkyl methacrylate blocks into methacrylic acid and/or metal methacrylate blocks. Of particular interest is the reaction with trimethylsilyl iodide. Under the same mild conditions, MM blocks are completely unreactive, while tBM blocks are cleanly converted to either methacrylic acid or metal methacrylate blocks. As a consequence of this unexpected selectivity, we also report the preparation of the new block copolymers, poly(methyl methacrylate-b-potassium methacrylate) (MM-b-MA.K) and poly(methyl methacrvlate-b-methacrylic acid) (MM-b-MA). 

Materials. Methyl methacrylate was a product of Rohm and Haas, and t-butyl methacrylate was obtained from Polvsciences, Inc. Potassium trimethylsilanolate (PTMS) was obtained from Petrarch Systems, Inc. Anhydrous lithium iodide, trimethylsilyl iodide (TMSI), and n-butyllit.ium (in hexanes) were purchased from Aldrich Chemical Co. 

Reaction of S-b-MM with Trimethylsilyl Iodide. The reaction was carried out under nitrogen in a 250-mL, round-bottom flask equipped with a magnetic stirrer. To a solution of S-b-MM-94/6-wt (5.01 g, 2.9 meq MM) in dichloromethane (50 mL) was added TMSI (1.3 g, 6.3 mmol) via syringe. The solution was refluxed for 22 hr. It was cooled, precipitated from methanol, washed with methanol, and dried, yielding 4.39 g. NMR, IR, and GPC analyses were virtually identical to those of the starting material. 

Reaction of S-b-tBM with Trimethylsilyl Iodide. The reaction was carried out under conditions similar to that employed for the reaction of S-b-MM with TMSI. A mixture of S-b-tBM-87/13-wt (10.0 g, 9.3 meq tBM) in dichloromethane (100 mL, dried over 3 A sieves) was treated with TMSI (5.0 g, 25 mmol) and was stirred for 4 hr at room temperature, resulting in a dark red solution. The solvent was partially evaporated, and the residue was precipitated from methanol. The precipitate was washed with several portions of methanol and was dried. It was redissolved in 1 9 water-THF (300 mL), 3 mL of cone. HC1 was added, and the mixture was refluxed for 2 hr. The solvents... 

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