Ketene f-Butyldimethylsilyl Methyl Acetal

Preparative Method obtained by reaction of methyl acetate with lithium diisopropylamide in THF/HMPA and subsequent trapping with f-butyldimethylchlorosilane (72% yield).  

Handling, Storage, and Precautions should be stored in the absence of moisture at —15 °C. 

Silylation. The reagent silylates a variety of substrates (alcohols, acids, thiols, phenols, imides) under mild conditions (a catalytic amount of p-toluenesulfonic acid is occasionally added) with excellent yields (91-100%).  

Pummerer Reaction. The reagent transforms sulfoxides in the presence of catalytic amounts of zinc iodide into the corresponding a-silyloxy sulfides (eq 1). Vinyl sulfoxides undergo a Michael-Pummerer type reaction to give y-silyloxy-y-phenylthio esters (eq 2).  

As an extention of this reaction, the reagent promotes the intramolecular Pummerer-type rearrangement of ffl-carbamoyl 

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Related Reagents. For comparisons and more details, see also those entries that deal with other silyl ketene acetals, in particular 1-f-Butylthio-l-f-butyldimethylsilyloxyethylene, ketene f-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. t-Butyl a-Lithioisohutyrate Dilithio-acetate Ethyl Lithioacetate Ketene Bis(trunethylsilyl) Acetal Ketene f-Butyldimethylsilyl Methyl Acetal l-Methoxy-l-(tri-methylsilyloxy)propene l-Methoxy-2-trunethylsilyl-l-(tri-methylsilyloxy)ethylene Tris(trimethylsilyloxy)ethylene. 

SILYLATION Bis(trimethylsilyl)urea. t-Butyldimethylchlorosilane. t-Butyldimethylsilyl trifluoromethanesulfonate. Chlorotrimethylsilane. Dimethyl(2,4,6-tri-f-butylphenoxy)chlorosilane. Ethyl trimethylsilylacctate. Ketene t-butyldimethylsilyl methyl acetal. N-Methyl-N-(/-... 

The silyl ketene acetal rearrangement can also be carried out by reaction of the ester with a silyl triflate and tertiary amine, without formation of the ester enolate. Optimum results are obtained with bulky silyl triflates and amines, e.g., f-butyldimethylsilyl triflate and (V-methyl-Af, /V-dicyclohcxylaminc. Under these conditions the reaction is stereoselective for the Z-silyl ketene acetal and the stereochemistry of the allylic double bond determines the syn or anti configuration of the product.243... 

O-Methyl-0-f-butyldimethylsilyl ketene acetal undergoes a i yn-selective addition to the same nitrone in the presence of TBDMS triflate (eq 38). awh -Selectivity is observed with Bp3 OEt2. Additions of O-methyl-0-f-butyldimethylsilyl ketene acetal to other chiral nitrones promoted by TBDMS triflate have also been reported. ... 

Ketene silyl acetals. The enolsilylation of esters is highly dependent on the bases used. Contrasting stereoselectivities in the silylation of methyl a-f-butyldi-methylsiloxyacetate are found with respect to the reaction conditions The ( )-isomer is obtained in the trimethylsilylation promoted by lithium tetramethylpiperidide, and the (Z)-isomer from the reaction with t-butyldimethylsilyl chloride in the presence of LHMDS and HMPA. 

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