Trimethylsilyl phosphates

The first pure P-O-Si organic compound to be isolated was tris(trimethylsilyl) phosphate, bp = 232-234°C, which was made from hexamethyl disiloxane and phosphorus pentoxide (9.260). Other tris(alkylsilyl) phosphates can be made in a similar way, but alternative methods of preparation... 

Triphenylphosphoranylidene) Ethylene DMA Tris(hexafluoro-iso-propyl) Tris(trimethylsilyl)phosphate sucdnic anhydride dioxythiophene phosphate... 

Zhang J, Wang J, Yang J, NuLi Y (2014) Artihcial interface deriving from sacrificial tris (trimethylsilyl)phosphate additive for lithium rich cathode materials. Electrochim Acta 117 99-104. doi 10.1016/j.electacta.2013.11.024... 

Sulfonyldipropionitrile, cf. Figure 2.20, is structurally different from commonly used compoimds as additives for an LiMn204 cathode, e.g., tiis(pentafluorophenyl) borane (76), vinyl ethylene carbonate (77), fluoroethylene carbonate (78), hexamethyldisilaz-ane (79), tris(trimethylsilyl) borate (80), or tris(trimethylsilyl) phosphate (81). 

Transformation of the brominated polyethersulfones to the phosphonated polyethersulfones was carried also using Ni catalysts. Mulhaupt et al. [71 ] have prepared phosphonated polyethersulfones via the treatment of the brominated polyethersulfone with tris-(trimethylsilyl)phosphate (TMSP) catalyzed with NiCl2 and subsequent methanolysis of the reaction product (Scheme 13). 

The reaction of N-heterocyclic chlorosilylene (LSiCl, L = PhC(NtBu)2) (5) with lithiumphosphide LiP(SiMe3)2 (6) leads to generation of the N-heterocyclic bis(trimethylsilyl)phosphino-silylene by virtue of phosphanylation of the chlorosilylene (Scheme 6.4.3.1) (7). The low-valent silicon functionality is retained and the phosphorus atom possesses labile TMS groups that can enable additional transformations. The starting materials, silylene chloride [LSiCl] (5) and lithium bis(trimethylsilyl) phosphate [LiP(SiIVIe3)2] (6) can be prepared according to the literature procedures. 

Lithium bis(trimethylsilyl)phosphate, LSiCl, toluene, hexane. 

Lebreton et al. have developed an efficient and simple one-pot synthesis for 1-hydroxy-l,l-bis(phosphonic acid) (453) starting from commercial or synthetic carboxylic acid (451), catechol borane (452), tris(trimethylsilyl) phosphate (Scheme 112). ... 

If alkyl groups are attached to the ylide carbon atom, cis-olefins are formed at low temperatures with stereoselectivity up to 98Vo. Sodium bis(trimethylsilyl)amide is a recommended base for this purpose. Electron withdrawing groups at the ylide carbon atom give rise to trans-stereoselectivity. If the carbon atom is connected with a polyene, mixtures of cis- and rrans-alkenes are formed. The trans-olefin is also stereoseiectively produced when phosphonate diester a-carbanions are used, because the elimination of a phosphate ester anion is slow (W.S. Wadsworth, 1977). 

The most general method for the simultaneous analysis of oxyanions by gas chromatography is the formation of trimethylsilyl derivatives. Trimethylsilyl derivatives of silicate, carbonate, oxalate, borate, phosphite, phosphate, orthophosphate, arsenite, arsenate, sulfate and vanadate, usually as their ammonium salts, are readily prepared by reaction with BSTFA-TMCS (99 1). Fluoride can be derivatized in aqueous solution with triethylchlorosilane and the triethylfluorosilane formed extracted into an immiscible organic solvent for analysis by gas chromatography [685). 

In this context, it is interesting to note that the first synthesis of 2, 3 -0,0-cyclic phosphorothioate 22a was reported by Eckstein in 1968 [25], He also isolated pure Rp diastereomer by fractional crystallization of the triethylammonium salts [26] and used it as reference to determine the absolute configurations of the other phosphorothioate analogues [27], 2, 3 -0,0-Cyclic H-phosphonate 20a was used as a key substrate for the synthesis of uridine 2, 3 -0,0-cyclic boranophosphate 27. Silylation of H-phosphate 20a gave the phosphite triester 25 (two diastereomers). Its boronation, with simultaneous removal of the trimethylsilyl group, was achieved by its reaction with borane-A.A-diisopropylethylamine complex (DIPEA-BH3). 

A novel synthesis of iodothiazole 38 takes advantage of Wiemer s protocol for the synthesis of vinyl iodides from ketones <06JOC5031>. The thiazolyl phosphate 37, prepared from 2-isopropylaminothiazoline-4-one 36, is converted to the desired iodothiazole 38 upon treatment with in situ generated trimethylsilyl iodide. This iodide is a key intermediate in the synthesis of the quinolone substructure of the protease inhibitor BILN 2061. 

Attack on Oxygen. Nitrones have been deoxygenated to the parent imine with trimethyl phosphite under vigorous conditions.45 Virtually quantitative yields of the enol-phosphates (54) and (55) were obtained from the reaction of tris(trimethylsilyl) phosphite with a-diketones and /j-benzoquinone. 4 6... 

The phosphitylation procedure activated by tetrazole led to the phosphite structure (step a) which was effectively oxidized by TBHP to yield the corresponding phosphate (step b). Finally all 2-cyanoethyl protecting group were removed by the action of DBU in the presence of the silylating reagent bis(trimethylsilyl)acetamide BSA (step c). The latter is indispensable to secure total deprotection. 

The etiolate intermediate, generated by the addition of higher-order cyanocuprates to enones, has been trapped with several electrophiles. Thus the addition of trimethylsilyl chloride, diethyl or diphenyl phosphorochloridate and iV-phenyltrifluoro methane-sulphonamide affords the corresponding vinyl silyl ethers, vinyl phosphates and vinyltri-flates. " ... 

The introduction of the allylic silane moiety required for the intermolec-ular Hosomi-Sakurai reaction is depicted in Scheme 16. Following the formation of the enol triflate 97, a Stille coupling provided excess to the allylic alcohol 98 [51]. The allylic alcohol (98) was endowed with a phosphate leaving group for the subsequent allylic substitution. Utilizing a trimethylsilyl cuprate as nucleophile for the 5 2 reaction, the allylic phosphate was converted into the allylic silane 89. A useful substrate-induced diastereoselectivity in favour of (14i )-89 was encountered at small scale but decreased significantly upon up-scaling. 

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