Related reagents silyl ketene acetals

Related Electrophilic Silyl Ketene Acetal Reagents. A... 

Following from the examples of allyltrichlorosilanes 21.5, Denmark introduced the related eno)g4 richlorosilanes 21.97 (Scheme 21.13) to cany out Mukaiyama-lype nucleophilic additions to carbonyl compounds. " According to Mayr s nucleophilicity scale, silyl enol ethers derived from aldehydes and ketones and, in particular, silyl ketene acetals are even more powerful nucleophilic reagents than the respective allyl silanes. Indeed, the aldol-type addition of trichlorosilyl enol ethers 21.97a-d to aldehydes 21.4 proceeds readily at room temperature without a catalyst exhibiting simple first-order kinetics in each component (Scheme 21.13), which contrasts with the lack of reactivity of allyl silanes in the absence of a catalyst. 

Related Reagents. For comparison and more details, see also those entries that deal with other silyl ketene acetals, in particular 1-f-butylthio-l-f-butyldimethylsilyloxypropene, ketene t-butyldimethylsilyl methyl acetal, and analogs. 

Related Reagents. f-Butyl a-Lithiobis(trimethylsilyl)acetate f-Butyl Trimethylsilylacetate Ethyl Bromozincacetate Ethyl Lithioacetate Ethyl Trimethylsilylacetate Ketene Bis(trimethyl-silyl) Acetal Ketene f-Butyldimethylsilyl Methyl Acetal l-Methoxy-2-trimethylsilyl-l-(trimethylsilyloxy)ethylene Methyl (Methyldiphenylsilyl)acetate Methyl 2-Trimethylsilyl-acrylate Triethyl Phosphonoacetate Trimethylsilylacetic Acid. 

Related Reagents. Methoxy(phenylthio)(trimethylsilyl)-methane (7) is prepared by metalation-silylation of phenyl-thiomethyl methyl ether.[Methoxy(phenylthio)(trimethylsilyl)-methyl]lithium (8), prepared from (7) by metalation with s-butyllithium in the presence of TMEDA, undergoes clean and efficient Peterson alkenation with aldehydes to give ( )-ketene-0,5-acetals stereoselectively, which can then be hydrolyzed to thioesters (eq 10). ... 

Full details have appeared of application of the C-silylated ester Me3 iCH2C02Et to silylations of alcohols mediated by fluoride ion (cf. 1,170)." In an extension of earlier work with the TMS enol ethers of esters (4,154), ketene methyl TBDMS acetal (50) has been advocated as a stable readily available reagent for conversion of alcohols to TBDMS ethers under mild conditions." In a related approach the O-silylated derivatives (51) and (52), readily formed from acetylacetone (R = Me) or methyl acetoacetate (R = OMe), have been found to be effective reagents for the transformation of alcohols to their TBDMSand TMS ethers," respectively reagents (51) require acid catalysis whereas (52) react without catalyst. Some further details have appeared... 

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