Aldehydes silanes

Another example concerns the immobilization of a biocatalyst—the enzyme glucose oxidase (GOD)—to the silica nanotubes [4]. GOD was immobilized, on both the inside and outside surfaces, via the aldehyde silane route. These GOD-nanotubes (60 nm diameter) were dispersed into a solution containing 90 mM glucose and also the components of the standard dianisidine-based assay for GOD activity. A GOD activity of 0.5 0.2 units per milligram of nanotubes was obtained. These studies also showed that protein immobilized via the Schiff base route is not leached from the nanotubes, where GOD activity ceased when the nanotubes were filtered from the solution. 

Scientific aldehyde silane or epoxide Poly-L-lysine Amino-modified oligonucleotides and PCR products, or proteins PCR products or proteins ... 

Tl mediated Inter or intramolecular addition of allytic silanes to ouMnsaiurated ketones or to aldehydes. 

In a cross-coupling benzoin condensation of two different aldehydes, usually a mixture of products is obtained, with the ratio being determined by the relative stabilities of the four possible coupling products under thermodynamic control. If, however, an acyl silane, e.g. 5, is used as the donor component, the a-silyloxy-ketone 6 is obtained as a single product " ... 

Butenyl(trimethyl)silane reacts with aldehydes in the presence of titanium(IV) chloride to give sj/77-products with excellent stereoselectivity. Reactions of the (Z)-2-butenylsilane are less stereoselective although jyn-products are still preferred23. 

In contrast, ( )- and (Z)-2-butcnyl(trifluoro)silanes undergo stereoselective fluoride-induced reactions with aldehydes to give anti- and. sy -products, respectively37. 

Trimethyl(l-phenyl-2-propenyl)silane of high enantiomeric excess has also been prepared by asymmetric cross coupling, and reacts with aldehydes to give optically active products in the presence of titanium(IV) chloride. The stereoselectivity of these reactions is consistent with the antiperiplanar process previously outlined75. 

Aldehyde 106-110, 121f., 125, 144-147, 181-195, 232-236, 347ff 487f., 498, 521, 524, 5261, 544ff 557/1, 560, 599, 603ff. aus Acyl-malonsaure-diathylestcr durch re-duktive Spaltung mit Natriumboranat 195 aus N-Alkyl-nitrilium-Salzcn und Triathyl-silan 122... 

Dihydropyrans [71] and 4-dihydropyranones [72] have been prepared by BF3 or Me2AlCl catalyzed Diels-Alder reactions of alkyl and aryl aldehydes with dienes 72 and 73 (Equations 3.20 and 3.21). Allylic bis-silanes are useful building blocks for synthesizing molecules of biological interest [73], 4-Pyra-nones have been obtained by cerium ammonium nitrate (CAN) oxidation of the cycloadducts. 

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. 

Allylic silanes react with aldehydes, in the presence of Lewis acids, to give an allyl-substituted alcohol. In the case of benzylic silanes, this addition reaction has been induced with Mg(C104)2 under photochemical conditions. The addition of chiral additives leads to the alcohol with good asymmetric induction. In a related reaction, allylic silanes react with acyl halides to produce the corresponding carbonyl derivative. The reaction of phenyl chloroformate, trimethylallylsilane, and AICI3, for example, gave phenyl but-3-enoate. ... 

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