Tris silyl chloride

StericaHy hindered silyl ethers such as ferZ-hutyl dimethyl silyl, / fZ-butyldiphenylsilyl, and tricyclohexylsilyl have been proposed as alternatives to trityl ethers. Reaction of sucrose with 3.5 molar equivalents of ferZ-hutyl dimethyl silyl chloride produces the 6,1/6 -tri-O-silyl derivative in good yield (27). 

The tris(trimethylsilyl)silyl ligands can be easily modified by reactions with silyl chlorides, as shown with a series of phenylated species Mes Ph SiCl (n = 0-3). Furthermore, triisopropyl, thexyldimethylsilyl, or tert-butyldimethylsilyl substitution are all easily possible.190 The crystallographic characterization of some of the alkali metal derivatives indicates a direct correlation between ligand size and resulting structural parameters. 

The reaction of toluene solutions of indium trichloride and tris(trimethylsilyl)arsine resulted in the formation of a very fine dark-brown powder subsequently annealed up to 400°C to drive to completion the elimination of trimethyl-silyl-chloride. Nanocrystalline InAs was obtained. Similar reactions with InBr3 and Inl3 and P compounds have been discussed. Previously a similar reaction was described by Uchida et al. (1993) (reaction of indium acetylacetonate with tris(trimethylsilyl)arsine in refluxing triglyme). Subsequently the reaction with InCl3 was used by Guzelian et al. (1996) in the preparation of nano-crystal quantum dots. They compared different preparation methods and techniques useful to isolate specific size distributions. 

The trialkylstannyl derivatives are obtained directly by reaction of tri-methyltin chloride with 2-lithiooxazole (87S693), but in the case of the silyl compounds an extra step is required, involving the base-catalyzed thermal ring closure of the silylated ring-opened oxazole (Scheme 81)(84CC258 87JOC3413). 

Triphenylsilyl azide, a320 Tripropylsilyl chloride, c258 Tris(dimethylamino)silyl chloride, c257a... 

The direct reaction of (trichloromethyl)chlorosilanes was applied under the same reaction condition described in the direct reaction of elemental silicon with (dichloromethyl)chlorosilanes above. In this reaction, an admixed gases of hydrogen chloride and 40 wt% (trichloromethyl)chlorosilanes in toluene injected using a syringe pump in pre-heater zone was fed into a reactor charged with elemental silicon (90%) and copper catalyst (10%) (Fig. 1). This reaction afforded no tetrakis (chlorosilyl)methane instead, tris(silyl)methanes and bis(silyl)methanes were obtained, which were the same products derived from the reactions of (dichloromethyl)chlorosilanes or chloroform, and (chloromethyl)chlor-osilanes or methylene chloride, respectively. This result may be rationalized by decomposition of (trichloromethyl)chlorosilanes to (dichloromethyl)-chlorosilanes and (chloromethyl)chlorosilanes on silicon-copper contact mass during the reaction, followed by reaction with elemental silicon to afford the products or the decomposition tetrakis(silyl)methane products.16... 

Silyl esters are generally prepared from carboxylic acids and the corresponding silyl chlorides or silyl triflates in the presence of base, e.g. pyridine, TEA, imidazole, in CH2CI2, CHCI3, DMF, or A-Methyl-C)-(trimethylsilyl)acetamide or A,0-bis(tri-... 

TBDPS ether is visible under UV light and thus it is more advantageous than the corresponding TBDMS ether if there is no chromophore present in the alcohol. Selective protection of the primary alcohol can be achieved as shown below. Silyl chloride and cleavage by-product silylol are both lachrymators and therefore the reactions should be carried out in the hood. The procedures for protection and cleavage are applicable to other silyl ethers such as ferf-butyldimethylsilyl, trimethylsilyl, and tri-isopropylsilyl. 

We also attached three steroid substrates to an iodophenyl template in 16 (Scheme 6-7) using a tris-silyl ether link, and saw that the template could direct selective radical-relay chlorination to all three tethered substrate species in the same work we reported a similar finding when a thiophene ring was the triply tethered template [49]. Thus the sulfur atom of thiophene can perform radical relay. In these triple catalytic functionalizations, the more reactive sulfuryl chloride was the preferred reagent. 

Among other heteroatom nucleophiles, trimethylsilyl chloride is widely used [36-41] and tri(isopropyl)silyl chloride was also reported [42-44]. Tin derivatives include trimethyl- [33,45-48] and tributyltin chloride [34,49-51]. Several sulfur transfer reagents have been used (Table 1) [52], including a wide range of disulfides [23, 29, 34, 48, 53-55], succinimide derivatives [52], phenylsulfinyl chloride, [45,46,56-58], and elemental sulfur [52,59]. 

The magnesium-mediated reductive trifluoromethylation also works for other structurally diverse chlorosilanes. Chlorotriethyl-silane, f-hutyldimethylsilyl chloride, and tris(trimethylsilyl)silyl chloride have been applied to prepare corresponding trifluoro-methyl-containing silanes. However, the reductive trifluoromethylation did not take place with other electrophiles such as aldehydes, ketones, allyl bromide, benzyl chloride, or tributyltin chloride. Even tributyltin hydride and allyltrimethylsilane showed no reactivity The reason for such behavior is not clear. Probably, chlorosilanes play an important role during the reductive trifluoromethylation both as a silylating agent and a single-electron transfer promoter. 

A new preparation of trimethylsilyl ethers from alcohols employs bis(tri-methylsilyl) ether, often regarded as inert , in the presence of pyridinium tosylate these conditions are mildly acidic, in contrast to the more usual basic silylation media. t-Butyldimethysilyl perchlorate has been prepared [equation (10)] and is a more reactive reagent than the corresponding silyl chloride for the... 

A neat mixture of the /l-unsaturated ketone (10mmol), triethylsilane (11 mmol), and tris(triphenylphosphine)rhodium(i) chloride (0.01 mmol) was stirred at 50°C for 2h, and the product silyl enol ether was distilled directly (yields 90-98%). 

Rhodium-catalysed addition (10) of hydridosilanes (Chapter 17) to a/3-unsaturated carbonyl compounds can be performed regioselectively, to afford either the product of 1,2-addition, or, perhaps more usefully, that of 1,4-addition, i.e. the corresponding silyl enol ether this latter process is an excellent method for the regiospecific generation of silyl enol ethers. Of all catalyst systems investigated, tris(triphenylphosphine)rhodium(l) chloride proved to be the best. 

Benzene reacted with excess 3 in the presence of aluminum chloride at room temperature for 4 h to give peralkylated product," hexakis[2-(methyldichloro-sily I )ethyljbenzcne (4a) and other alkylated products pentakisl2-(mcthyldichloro-silyl)ethyl]benzenc (4b), tetrakis 2-(methyldichlorosilyl)ethyljbenzene (4c), tris 2-(methyldichlorosilyl)ethyl]benzene(4cl), and bis 2-(methyldichlorosilyl)ethylJ-benzene (4e) (Eq. (6)). The product distributions were plotted against mole ratios of 3/benzene in Fig. I. 

An alternative method of synthesis of N3P3Cl6 has been developed recently, based on the reaction of tris (trimethylsilyl) amine and phosphorus pentachloride (40). This reaction either preferentially leads to the formation of N3P3C16 or to an N-silylated phosphoranimine intermediate C13P - NSiMe3, depending on the reaction conditions used. Thus the reaction between tris (trimethylsilylamine) and PC15 in methylene chloride at 40° C affords a mixture of cyclo and linear phosphazenes, which has been shown by an NMR analysis to contain up to 76% of N3P3C16 (Eq. 2). 

Fluoride ion catalyzes the hydrosilylation of both alkyl and aryl aldehydes to silyl ethers that can be easily hydrolyzed to the free alcohols by treatment with 1 M hydrogen chloride in methanol.320 The most effective sources of fluoride are TBAF and tris(diethylamino)sulfonium difluorotrimethylsilicate (TASF). Somewhat less effective are CsF and KF. Solvent effects are marked. The reactions are facilitated in polar, aprotic solvents such as hexamethylphosphortriamide (HMPA) or 1,3-dimethyl-3,4,5,6-tetrahydro-2(l //)-pyrirnidinone (DMPU), go moderately well in dimethylformamide, but do not proceed well in either tetrahydrofuran or dichloromethane. The solvent effects are dramatically illustrated in the reaction of undecanal and dimethylphenylsilane to produce undecyloxyphenyldimethylsi-lane. After one hour at room temperature with TBAF as the source of fluoride and a 10 mol% excess of silane, yields of 91% in HMPA, 89% in DMPU, 56% in dimethylformamide, 9% in tetrahydrofuran, and only 1% in dichloromethane are obtained (Eq. 164).320... 

The 1,4-reduction of a,/3-unsaturated aldehydes is best carried out with diphenylsilane in the presence of zinc chloride and tetrakis(triphenylphosphine) palladium436 or a combination of triethylsilane and tris(triphenylphosphine) chlororhodium 437 Other practical approaches use phenylsilane with nickel (0) and triphenylphosphine438 and diphenylsilane with cesium fluoride.83 It is possible to isolate the initial silyl enol ether intermediate from the 1,4-hydrosilylation of o, /3-unsaturated aldehydes (Eq. 264).73,411 The silyl enol ethers are produced as a mixture of E and Z isomers. 

Organic sulfinylamines RNSO are typically prepared by the reaction of a primary amine or, preferably, a silylated amine with thionyl chloride. A recent example is the preparation of FcNSO (Fc=ferrocenyl).126 The important reagent Me3SiNSO is obtained by the reaction of thionyl chloride with tris(trimethylsilyl)amine at 70 °C in the presence of A1C13.127... 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

---