Ethyl lithio acetate

Lead tetraacetate, oxidation of a hydrazone to a diazo compound, 50, 7 Lithio ethyl acetate, 53, 67 Lithium, reductions in amine solvents, 50, 89 Lithium aluminum hydride, reduction of exo-3,4-dichloro-bicyclo-[3.2.l]oct-2-ene to 3-chlorobicyclo[3.2.l]oct-2-ene, 51, 61... 

B. Lithio Ethyl Acetate. The reaction flask is immersed in a dry ice-acetone bath, and the solution is stirred for 15 minutes to achieve temperature equilibration. After this time, 22.1 g. (0.250 mole) of ethyl acetate is added dropwise over a 10-minute period. Stirring is continued for an additional 15 minutes to complete the formation of lithio ethyl acetate (Note 6). 

Solutions of lithio ethyl acetate prepared by this method are stable indefinitely at —78°, but decompose rapidly if allowed to reach room temperature. 

Preparation. Lithio ethyl acetate is prepared in essentially quantitative yield by the reaction of ethyl acetate with lithium bis(trimethylsilyl)amide2 in THF at —78°. It has been prepared also but in about 15% yield by the addition of ethyl... 

Lithio ethyl acetate, 53, 67 Lithium, reductions in amine solvents, 50, 89... 

B. Lithio Ethyl Acetate. The reaction flask is immersed in a dry ice-acetone bath, and the solution is stirred for 15 minutes to achieve temperature equilibration. After this time,... 

Regio- and stereoselective ring opening of 283 with Et2AlN(CH2Ph)2, prepared in situ from Et2AlH and dibenzylamine, furnishes in 78% yield the amino alcohol 287, which is converted in four steps to aldehyde 288. An aldol reaction of 288 with lithio ethyl acetate proceeds by a nonchelated Felkin-Anh pathway to provide predominantly the a /-selective a-hydroxy ester (89 11 diastereomeric mixture), which is tosylated and separated chromatographically to afford 289. This compound is converted in four steps to (+ )-e/7/-castanospermine (290) (Scheme 67). 

Lithio ethyl acetate is prepared in quantitative yield by reaction of LHMDS with ethyl acetate in THF at —78 °C. Reaction with carbonyl compounds leads to condensation products in high yield (eqs 3 and 4). No racemization of the a-silyloxy esters occurs (eq 4). 

This procedure illustrates the use of lithio esters for the preparation of /3-hydroxy esters. Isopropyl and /-butyl /3-hydroxy-/8,/3-diphenylpropionate may be prepared in approximately 80% yields by using isopropyl or /-butyl acetates in place of ethyl acetate.2 This procedure is generally more convenient than the Reformatsky reaction for the preparation of such esters. Under similar conditions ethyl acetate may conveniently be condensed with various aldehydes or ketones to give the corresponding /8-hydroxy esters.4... 

Peterson olefination. This reaction usually shows little or no selectivity. In contrast, the reaction of ethyl lithio(trimethyIsilyl)acctate with cn-substituted cyclohexanones can show moderate to high (Z)-selectivity. (Z)-Sciectivity is somewhat higher in reaction with ethyl potassio(trimethylsilyl)acetate or t-butyi lithio(trimethylsilyl)acetate, but yields... 

A study carried out by Kocienski and Lythgoe flrst demonstrated the trans selectivity of the Julia coupling process. The authors found the i uctive elimination could best be carried out with the acet-oxy or benzoyloxy sulfones. If the lithio sulfone derivative is used for addition to the carbonyl, the reaction can be worked up with acetic anhydride or benzoyl chloride to obtain the alkene precursor. In cases where enolization of the carbonyl is a complication, the magnesium derivative can frequently be used successfully. A modification of the reductive elimination was found to be most effective. Methanol, ethyl acetate/methanol or THF/methanol were the solvents of choice and a temperature of -20 C was effective at suppressing the undesired elimination of the acetoxy group to produce the vinyl sulfone. With these modifications of the original procedure, the ability of the reaction to produce dienes as well as rran.r-disubstituted alkenes was demonstrated, llie diastereoisomeric erythro- and threo-acetoxy sulfones could be separated and it was demonstrated that both isomers were converted to the rrans-alkene. It... 

The optimum conditions for the formation of the 3-lithio derivative of diazepam involved the use of 2 equivalents of LDA in THE at 25 °C. The anion so formed reacted with alkyl halides (e.g., Mel) and esters (e.g., ethyl acetate) to give the 3-alkyl and 3-acyl derivatives (Scheme 12) (77 R = alkyl, acyl). The reaction with aldehydes and ketones furnished carbinols and in the case of benzaldehyde the initially formed carbinol (78 R = Ph) dehydrated to the alkylidene derivative (79) on longer reaction times <81JOC3945>. A similar dehydration was noted also with cyclohexanone. 

Related Reagents. t-Butyl Q -Lithiobis(trimethylsilylacetate Ethyl Lithioacetate Ethyl Lithio(trimethylsilyl)acetate Ethyl Trimethylsilylacetate Triethyl Phosphonoacetate Trimethylsilyl-... 

Many of the reactions of ethyl trimethylsilylacetate and its analogues involve the ester enolate these are discussed in Ethyl Lithio(trimethylsilyl)acetate. 

Related Reagents. t-Butyl a-Lithiobis(lrimethylsilyl)acetate t-Butyl Trimethylsilylacetate Dilithioacetate Ethyl Bromozin-cacetate Ethyl Lithioacetate Ethyl Lithio(trimethylsilyl)acetate Ketene Bis(trimethylsilyl) Acetal Ketene t-Butyldimethylsilyl Methyl Acetal l-Methoxy-2-trimethylsilyl-l-(trimethylsilyloxy)-ethylene Methyl (Methyldiphenylsilyl)acetate Trimethylsilyl-acetic Acid. 

Related Reagents. f-Butyl a-Lithiobis(trimethylsilyl)acetate t-Butyl Trimethylsilylacetate Dilithioacetate Ethyl Lithio-(trimethylsilyl)acetate Ethyl Trimethylsilylacetate. 

Related Reagents. r-Butyl Trimethylsilylacetate N,N-T>i-methyl-2-(trimethylsilyl)acetamide Ethyl Lithio(trimethylsilyl)-acetate Ethyl 2-(Methyldiphenylsilyl)propanoate Ethyl Trimethylsilylacetate Lithioacetonitrile... 

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