Acetoxy silanes

Tetra(alkoxy) silanes such as tetra(methoxy)silane 58 [50, 64], tetra(ethoxy)silane 59 [50], tetra(acetoxy)silane Si(OAc)4 113 [51], tetra(dimethylamino)silane Si(NMe2)4 114 [52, 53], or tetrakis(l-pyrrolidino)silane 115 [53] are readily prepared from SiCh 57 and are available in any amounts. 

On heating with tetra(acetoxy)silane Si(OAc)4 113 in AcOH in the presence of catalytic amounts of ZnCl2 uridine 1 is converted via 136, in 54% yield, into O-peracetylated 2,2-anhydrouridine 137 [70] (Scheme 3.12). 

Another direct method reports the use of anhydrous sodium acetate and silicon tetrachloride to prepare acetoxy silanes (Scheme 3.2). The main drawback of the... 

They conclude that the copolymers with higher molecular weights are obtained with ureidosilanes, while those with the lower molecular weights are obtained with chloro and acetoxy silanes, because in both these cases, degradation side reactions occur with the acids formed (HCl and CH3COOH). 

The term silanes is often loosely used to denote organofunctional silanes. Such molecules are of the type Y-(CH2)3-Si-(OX)3, in which Y is an organofunctional group and OX is an ethoxy or methoxy group. In this example, the silane is a trialkoxy silane. Di-and mono alkoxy silanes and acetoxy silanes are also available commercially. This... 

H3C—SiCl3 H3C—COOH In hexane Methyltris- (acetoxy) silane 92 261... 

Der intramolekulare RingschluB von 1 -Acetoxy-2-nitro-ethan mit Chlor-trimethyl-silan/ Triethylamin in Benzol fuhrt ebenfalls in guten Ausbeuten zu 3-Acetoxymethyl-5-trime-thylsilyloxy-4,5-dihydro-l,2-oxazol (65%)3 ... 

Upon addition of boron trifluoride etherate, acetoxylactam 8 eliminates an acetoxy group to produce A-acyliminium ion 9. The indo-lizidinone 10 is formed diastereomerically pure in an iminium-ion-ini bated cyclization reaction of the Overman type ending in a vinyl-silane.14... 

Tris(2-hydroxyphenyl)amine reacts with organyltrichlorosilanes, e.g. phenyltrichloro-silane, more slowly and at higher temperature than with the acetoxy derivative402. 

Silan (2-Acetoxy-l-methyl-ethyl)-dimethyl- E18/1, 705 [Kat. Hydrosilylier.]... 

Preparation of the temporary connection was achieved by reaction of acetoxy lactam 316 with allyl(chloro)silane 317, generating the A -silyl species 318. Exposure to TMSOTf at 0 °C effected in situ formation of the /V-acyliminium species, which was trapped by the pendant allyl nucleophile, providing two out of the possible four dia-stereoisomeric cyclized products, 319 and 320 in a 4 1 ratio (Scheme 10-102). Formation of the two products may be accounted for by cyclic T. S.s where addition occurs onto the re face of the azetinone, anti to the sterically demanding silyl ether group through a chair-like or boat-like conformation. 

PI, the acetoxy end capped Dexsil polymer, reacts on exposure to moisture to form acetic acid and silanol end groups which self condense. The coatings were not transparent because some crystallization occurred before cure was completed. To correct for this, a highly functionalized coating was synthesized by reaction of methyltriacetoxy silane and 1,7 bis(hydroxydimethylsilyl)—m earborane which produced a prepolymer with one acetoxy crosslinking site per repeat (Scheme 1). 

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