Diethyl silane

A novel and versatile method for preparing polymer-supported reactive dienes was recently developed by Smith [26]. PS-DES (polystyrene diethyl-silane) resin 28 treated with trifluoromethanesulfonic acid was converted to a polymer-supported silyl triflate 29 and then functionalized with enolizable a,jS-unsaturated aldehydes and ketones to form silyloxydienes 30 and 31 (Scheme 4.4). These reactive dienes were then trapped with dienophiles and the Diels Alder adducts were electrophilically cleaved with a solution of TFA. 

As discussed in Section III, however, the formation of 11 is not particularly strong evidence for silylenoid species 10. Phenylsilane and diethyl-silane also gave di- and trisilanes upon treatment with L3RhCI (24). 

Thermolysis of hexamethylsilacyclopropane at 60-80°C generates dimethylsilylene and tetra-methylethylene. The half-life of this reaction is greater than nine days at room temperature (75JA2273). Dimethylsilylene can be trapped by various substrates when the thermolysis is conducted in their presence. For example, interception of dimethylsilylene with diethyl silane gave disilane (42) in 48% yield, whereas trapping with 2,3-dimethyl-1,3-butadiene gave 1,1,3,4-tetramethyl-l-silacyclopent-3-ene (43) in 34% yield (Equations (6) and (7)) <75JA7162>. 

The upper two curves in Figure 224, illustrating lower effectiveness, are perhaps the exceptions. The upper curve represents diethyl silane added to the reactor along with a non-reduced Cr(VI)/silica catalyst. As with other cocatalysts, the silanes were most effective with Cr(II)/silica. The second highest curve in Figure 224 represents Cr(II) /silica, but the cocatalyst was a polymer, poly-methylhydrosiloxane. Its diminished effectiveness can perhaps be attributed to the inability of such a large molecule to diffuse into the catalyst pore structure or the polymer/silica matrix. 

Hydrolysis in the silicones is usually just a special case of the reaction with organic halides. The most important reaction is the preparation of siloxanes by the hydrolysis of chlorosilanes and the subsequent condensation to form the commercially important polysiloxanes (see Chap. 15). Diethyl silane diol, (CjHs)2Si(OH)s, and the corresponding di-n-propyl and di-n-butyl diols have been made by hydrolyzing the dichlorosilanes. The trimethyl and triethyl silicon hydroxides have been prepared by the hydrolysis of complex organic silicon compounds containing the aceto and the amino group, respectively. ... 

Related Reagents. Polymer-supported diethyl silane ... 

More recently, Wang and co-workers reported on a solid-phase total synthesis of 1-p-methylcarbapenem 97 because of interest in its potent broad-spectrum antibiotic activity. In this total synthesis (Scheme 3.19), azetidinone 92, bearing a chiral auxiliary, was loaded onto polystyrene-diethyl-silane resin 91 to give 93, which was condensed with allyl bromoacetate to give supported azetidinone 94. Treatment with TMSCl in the presence of NaN(TMS)2 and diphenyl phosphorochloridate (DPPC) promoted a Dieckmann-type cyclization to give supported vinyl phosphate 95 with concomitant release of the chiral auxiliary. Vinyl phosphate resin 95 was treated with thiophenol to give supported 1-P-methylcarbapenem 96, which was released from the solid support upon treatment with tetra-H-butylammonium fluoride (TBAF). 

When the chain bearing the allylsilane is one carbon longer, i.e., by the use of pentenylsilanes, cycloheptane rings can be formed. Both the (Z)- and (A )-isoiner of the (3-pentenyl)silanes can be synthesized selectively, but only the (Z)-(3-pentenyl)silane cyclized stereospecifically (complete 1,4-asymmetric induction). Both cthylaluminum dichloride and boron trifluoride diethyl ether complex promote the seven-membered ring formation35 43-48. 

Selenium oxide (SeO,) [7446-08-4], 25 Silane, tnchloro [ 10025-78-2], 83 Sodium azide [26628-22-8], 109 Sodium hydride [7646-69-7], 20 Stannane, tetrachloro- [7646-78-8], 97 Sulfuric acid, diethyl ester [64-67-5], 48 dimethyl ester [77-78-1], 62 Sulfuryl chloride isocyanate [1189-71-5], 41... 

The molar ratio of the III compound to the V compound is typically l/lO.t ] To obtain the desired semiconductor properties, dopants are added such as zinc (from diethyl zinc) or magnesium (from bis(cyclopentadienyl) magnesium) for p doping, and silicon (from silane) or selenium (from hydrogen selenide) for n doping. 

The monomer silane diol (5) was prepared by hydrolysis of the bis-chlorosilane (4) in the presence of sodium hydrogenocarbonate NaHCO at reflux of diethyl ether for 24 h. The hydrolysis was quantitative. The silane diol (5) was characterized by IR, where a narrow band at 3690 cm and a wide band between 3650 and 3050 cm were observed, respectively, for free t)=siOHand bonded t)= aoH Us H- and F-NMR spectra exhibited the expected signals and its Si-NMR spectrum showed a singlet at -i-16.4ppm characteristic for a 5 = siOH and no trace of the starting chlorosilane at -i-31 ppm. ... 

On the contrary, when bis(tributylstannomethyl)silane 100 is reacted with two eqniv-alents of w-butyllithinm in diethyl ether, only monohthiated compound 102 is formed . The donbly lithiated compound 101 is not accessible by this method (Scheme 35). 

The enantioselective deprotonation of the borane complex 248 of A-methylisoindoline was investigated by Simpkins and coworkers (eqnation 59) . Deprotonation with i-BuLi/(—)-sparteine (11) in diethyl ether at —78°C for 1 h, followed by quenching with chlorotrimethylsilane, yielded the silanes 251, ent-252, 252, ent-25 in a ratio of 86.3 0.4 6.3 7.0 after destroying the chiral centre at nitrogen by treatment of the whole mixture with triethylamine, an e.r. 253/ewf-253 of 86.7 13.3 is expected. 

Tuulmets, A. Nguyen, B. T. Panov, D. Sassian, M. Jarv, J. Kinetics of the Grignard Reaction with Silanes in Diethyl Ether and Ether-Toluene Mixtures. J. Org. Chem. 2003, 68, 9933-9937. 

The enantiomerically pure l-[(benzyl(dimethyl)silyl)methyl]pyrrolidine, obtained from ben-zyl(chloro)(dimethyl)silane and (5,)-2-(methoxymethyl)pyrrolidine , afforded after deprotonation and subsequent alkylation the diastereomerically pure (by NMR spectroscopy) (a-alkylben-zyl)silanes2. To obtain this high degree of diastereoselectivity, the alkylation had to be performed in the weakly complexing solvent diethyl ether. In THF a diastereomeric ratio of only 3 1 was found with iodomethane as alkylating agent. 

Suisse and co-workers have studied the asymmetric cyclization/silylformylation of enynes employing catalytic mixtures of a rhodium(i) carbonyl complex and a chiral, non-racemic phosphine ligand. Unfortunately, only modest enantioselectivities were realized.For example, reaction of diethyl allylpropargylmalonate with dimethylphenyl-silane (1.2 equiv.) catalyzed by a 1 1 mixture of Rh(acac)(GO)2 and (i )-BINAP in toluene at 70 °G for 15 h under GO (20 bar) led to 90% conversion to form a 15 1 mixture of cyclization/silylformylation product 67 and cyclization/ hydrosilylation product 68. Aldehyde 67 was formed with 27% ee (Equation (46)). 

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