Lithium trimethylsilanolate

At first the reactions of monochlorosilanes and siloxanes with lithium trimethylsilanolate, lithium phenyldimethylsilanolate, and lithium isopropylate were followed by gaschromatography, H NMR spectroscopy, and by nephelometric measurements [3,4]. Di- and trichlorosilanes and -siloxanes were then investigated in order to study the influence of strongly electron attracting substituents at the reaction centre [5], To prevent multiple substitution lithium ferr-butylate was used as the nucleophile for these compounds. All reactions gave high yields of products and no by-products were formed. 

Heating perfluorbutylsulfonyl fluoride 1316 with HMDS 2 and CsF in DMF affords the N-nonaflylamidine 1317 in 62% yield, trimethylsilyl fluoride 71, and HMDSO 7 [90]. Di(fluorosulfonyl)phenoxysulfonylmethane 1318 reacts with excess lithium trimethylsilanolate 98 to give, via 1319, vvdth elimination of HMDSO 7, the lithium salt 1320 in 95% yield [91] (Scheme 8.35). 

On treatment of the silylated dichloromethyl alcohols 1585 with butyUithium, lithium trimethylsilanolate, MesSiOLi, 98 is ehminated and the 1,1-dichloroolefins 1586 are formed in 40-82% yields [5, 6]. Likewise, treatment of sulfoxide 1587 at -30 °C with excess LDA results in ehmination of trimethylsilanol 4 to afford nearly... 

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. 

In summary, we have examined several new methods for cleaving ester groups in poly(styrene-b-alkyl methacrylates). Short blocks of methyl methacrylate are very difficult to hydrolyze, but can be cleaved with reagents such as lithium iodide and potassium trimethylsilanolate. These latter reagents, however, result in side-reactions which appear to crosslink the polymer. 

The synthesis of poly(dimethylsiloxane)macromonomers was also carried out anionically. The cyclic trimer D3 of dimethylsiloxane may be polymerized anionically, using lithium trimethylsilanolate as the initiator. Deactivation of the silanolate end groups may be performed with chlorosilyl functions. Yamashita et al. 29) successfully applied the unsaturated deactivators I and II... 

Considering the imderlying mechanism we assume that the reaction process is determined mainly by the chemical behaviour of [lithoxy(2,4,6-trimethylphenyl)methylidene]trimethylsilylphosphane formed in analogy to Scheme 1. Provided that this intermediate is allowed to split off lithium trimethylsilanolate, the... 

Lithium trimethylsilanolate (trimethylsilanol Li salt) [2004-14-0] M 96.1, in 120 (dec in air). Wash it with Et20 and pet ether. It sublimes at 180°/lmm as fine transparent needles. [Tatlock Rochnow J Org Chem 17 1555 1952, Beilstein 4 IV 3992.] Suspected CARCINOGEN. 

Diazomethyltrimethylsilane, (CHa)3SiCHN2, can be used in this synthesis with comparable results. A possible mechanism for this reaction involving loss of nitrogen with Wolff rearrangement and then loss of lithium trimethylsilanolate from the initial adduct is shown in equation (III). 

The modification of the Peterson reaction using an N-trimethylsilylamide anion instead of an a-silyl carbanion offers a promising route to the corresponding imines. Treatment of N-(p-tolyl)-N-trimethylsilylamide anion with carbonyl compounds yields the corresponding ketimines [400]. In particular, LiHMDS has been utilized for the preparation of N-trimethylsilylimines, which are useful as masked imine derivatives in the synthesis of yS-lactam antibiotics [401-407]. Reactions of LiHMDS with non-enolizable aldehydes, enolizable aldehydes, ketones, a diketone, and a-keto esters give the respective imines (Scheme 2.153) [408-413]. Chloro-trimethylsilane is added to convert the generated lithium trimethylsilanolate into hexamethyldisiloxane. 

The intermediate formed upon addition of an organolithium onto the carbonyl group of the heterocyclic starting material collapses by Peterson-type elimination of lithium trimethylsilanolate (Scheme 1-163). ... 

Scheme 1-163. Alkyllithium addition onto 3,3-dimethyl-l-(trimethylsilyl)-2-piperidone followed by the spontaneous elimination of lithium trimethylsilanolate.

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