Enolate of diethyl malonate

In this reaction the enolate of diethyl malonate adds to the p carbon of methyl vinyl ketone... 

Malonic ester synthesis (Section 21 7) Synthetic method for the preparation of carboxylic acids involving alkylation of the enolate of diethyl malonate... 

Magnesium enolates play an important role in C-acylation reactions. The magnesium enolate of diethyl malonate, for example, can be prepared by reaction with magnesium metal in ethanol. It is soluble in ether and undergoes C-acylation by acid anhydrides and acyl chlorides (entries 1 and 3 in Scheme 2.14). Monoalkyl esters of malonic acid react with Grignard reagents to give a chelated enolate of the malonate monoanion. 

One preparative procedure for achieving this reaction involves the acylation of the magnesium enolate of diethyl malonate with an acid chloride in benzene solution (cf. Expt 5.96), and the resulting aclymalonic ester is then heated to 200 °C with an arylsulphonic acid to effect the decarbethoxylation step. An illustrative example is the preparation of ethyl 3-oxopentanoate (ethyl propionyl-acetate, Expt 5.177). 

Treatment of the magnesium enolate of diethyl malonate with an aroyl halide, followed by decarboxylation... 

Either the tertiary amine or the quaternary ammonium salt can be stored as a stable equivalent of the exo-methylene compound. In our first example, the Mannich base with dimethylamine is first methylated with methyl iodide and then added to the conjugate addition reaction. Elimination of trimethylamine, which escapes from the refluxing ethanol as a gas, reveals the exo-methylene ketone in which the methylene group is exo to a chain. Fast conjugate addition of the stabilized enolate of diethyl malonate produces the product. 

The intermediacy of hydroxy ketone was invoked in the case of the addition of the enolate of diethyl malonate to dioxocin 219, which gave the trails-fused lactone 220 with high diastereoselectivity in good yield (65% Scheme 45) <2002JOC5307>. 

Nitro-l-(phenylsulfonyl)-l//-indole 829 undergoes nucleophilic addition reactions with enolates of diethyl malonate and cyclohexanone, lithium dimethylcuprate (Scheme 159), and indole anion (Equation 209) to afford the corresponding 3-substituted 2-nitroindoles in low to high yields <1997TL5603, 1999TL7615>. 

TV cirboxylic acid can best be made by a double alkylation of some specific enol(ate) equivalent. Ale enolate of diethyl malonate looks like a good bet. 

Exceptionally we have drawn the enolate of diethyl malonate as a carbanion. This is not generally recommended but you will see it and in this case, with the negative charge delocalized over the two ester groups, it is relatively harmless. 

The synthesis of barbiturate 36 (see Scheme 4.7) was performed next. The sodium enolate of diethyl malonate was reacted with 43, providing 44, which was converted to 2,2-disubstituted malonate 45 by reaction with allyl bromide. Reaction of 45 with urea in the presence of t-BuOK as base afforded the barbiturate 46, which was submitted to oxidative one-carbon demolition by the action of KMn04 to give carboxylic acid 47. Compound 47 was esterified with ethanol to give the target 36, but unfortunately in modest yields. 

Pelkey and Gribble showed that the enolate of diethyl malonate adds to 3-nitro-l-(phenylsulfonyl)indole (6a) at C-2 to form the trani-3-nitro-2-substituted indo-line 7 [7, 8]. The stereochemistry is confirmed on the basis of coupling constants. Other enolates also add to 3-nitroindoles 6 to form the tran -indolines 7 in moderate to good yields [8] (Table 1). 

The TT-allylpalladium intermediate 130, formed by the intramolecular carbopalladalion of 129, could be trapped with the enolate of diethyl malonate, with BusSnPh, with piperidine, or with phenol to afford a variety of cycloocta-1,3-diene derivatives 131-134 (Scheme 43).[ ii... 

This electrostatic potential map shows the enolate of diethyl malonate. This enolate has been used in a chemical synthesis of capsaicin, the substance most responsible for the fiery flavor of cayenne peppers. This synthesis is the basis of Problem 20.63 at the end of the chapter. 

A variation in this approach used the lithium enolate of diethyl malonate in a reaction with the allylic acetate moiety in 1.187. Malonate anion reacted with an intermediate 7c-allyl palladium species [formed from the allylic acetate moiety in 1.187, catalyzed hy the palladium (0) species] to give ethyl 6-(N-Boc amino)-7-(4-benzyloxypheny l)-2-carboethoxyhept-4-enoate, 1.188. ... 

High-dilution conditions for the intramolecular application of the malonic ester synthesis to the preparation of macrocyclic diesters have been reported yields between 9 and 50% are obtained. Dialklacyl phosphonates provide a new method for the acetylation of enolates including the sodium enolate of diethyl malonate. An alternative method for the generation of diester enolates involves the reductive a-deacetoxylation of an a-acetoxy diester (Scheme 30). The... 

Magnesium enolates play an important role in C-acylation reactions. The magnesium enolate of diethyl malonate, for example, can be prepared by reaction... 

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