Dialkylmalonates

Where R and R are identical, the dialkylmalonic ester may be prepared in one operation by treating 1 mol of ethyl malonate with 2 mots each of sodium ethoxide and the alkyl halide (usually bromide or iodide). 

Thus, decarboxylation of dialkylmalonic acid is a more complicated reaction compared to that of phenylmalonate and requires ATP and recycling of coenzyme... 

C. (Z)-3-Tributylstannylmethylene-4-iaopropyl-l, 1-eyclopentanediear-boxylie aoid, dimethyl ester (3). A flame-dried, 100-mL, round-bottomed flask equipped with a magnetic stirring bar is charged with argon, and 23.8 g (0.100 mol) of dialkylmalonate diester (2), 30.2 g (< 0.104 mol) of tributyltin hydride (Note 11), and 40 mg (0.25 mmol) of azobisisobutyronitnle (AIBN) (Note 12) are added neat (Notes 13, 14). The entire assembly is lowered into an oil bath maintained at 75-85°C, and the mixture is stirred. After an induction period of less than 30 min, an exothermic reaction occurs which produces a small amount of gas and a rise in the temperature of the oil bath (as much as 20°C for a small bath). After this point TLC shows that the reaction is essentially complete (Notes 15, 16, 17). Unpurified 3 thus obtained is suitable for protodestannylation. 

The results summarised in Table 4 show clearly that good yields of the 1 1 Michael adducts can be obtained in cathodically initiated reactions. It is not clear, however, why the reaction should fail for acrylonitrile even if dimerisation of the initially formed radical-anion is much faster thaq,protonation the resulting dimeric dianion should still be sufficiently basic to deprotonate dialkylmalonate esters. A feature of especial significance is the usefulness of esters of ethenetetracarboxylic acid. Apart from their use in EGB catalysed reactions they have been much used in stoichiometric amount. 

The monosubstituted malonie ester still possesses an activated hydrogen atom in its CH group it can be converted into a sodio derivative (the anion is likewise mesomeric) and this caused to react with an alkyl halide to give a C-disubstituted malonie ester. The procedure may accordingly be employed for the synthesis of dialkylmalonic and dialkylacetic acids ... 

Bis(crown ethers) connected by a flexible spacer are a source of intramolecular sandwich-type complexes with alkali metal ions <1992MI1>. A conformational analysis (based on a combination of semiempirical and ab initio methods) performed on 12-crown-3 38 and 12-crown-4 39 predicted that, in the case of sandwich-type complexation, the nucleophilic cavity of 12-crown-3 rather than that of 12-crown-4 is more prone to complexation with the Na+ ion. Accordingly, ion-selective electrodes based on bis(12-crown-3) derivatives with dialkylmalonate spacers displayed the highest selectivity for Na+ ions among the alkali and alkaline earths investigated, and superior to the Na+ selectivity reached with the bis( 12-crown-4) analogue <2003ANA(480)291>. 

Certain dialkylmalonates may be partially saponified to the acid esters, which decarboxylate to esters upon heating, Decarbethoxylation of dialkylmalonic esters may also be effected by heating at 220-230° with sodium ethoxide,... 

The alkylmalonic ester still contains one ionizable hydrogen, and on treatment with sodium ethoxide it, too, can be converted into its salt this salt can react with an alkyl halide—which may be iKe same as, or different from, the first alkyl halide— to yield a dialkylmalonic ester ... 

The acidity of malonic ester thus permits the preparation of substituted malonic esters containing one or two alkyl groups. How can these substituted malonic esters be used to make carboxylic acids When heated above its melting point, malonic acid readily loses carbon dioxide to form acetic acid in a similar way substituted malonic acids readily lose carbon dioxide to form substituted acetic acids. The monoalkyl- and dialkylmalonic esters we have prepared are readily converted into monocarboxylic acids by hydrolysis, acidification, and heat ... 

Carboxamides containing alkylamine arms like (34), synthesized from dialkylmalonate and ethylene-diamine, act as chelating dianionic N4-donors,44,45 whereas the geometric isomer (35) was prepared from 1,3-diaminopropane and chloroacetyl chloride.46 The hexadentate bis(pyrazine)-carboxamides (36) and (37) can be obtained by the addition of 1,3-propanediamine to the appropriate carboxylic acid.47 Compound (36), in the dianionic form, can be used to obtain homo- and hetero-metal bridged complexes, whereas (37) has been shown to yield tetranuclear copper(II) complexes involving opened-up dianionic ligand molecules.47... 

Dialkylmalonic anhydrides can be converted into dialkylketenes by heating them under diminished pressure at 100-200° 24... 

Dialkylmalonic acids. Dianions of carboxylic acids have been prepared using LDA in THF-HMPT (4,301-302). Krapcho reports that trianions (2) of monosubstituted malonic acids (1) can be prepared with 3 equiv. of n-butyl-lithium in THF at 0°. These can be alkylated by primary halides to give dialkylmalonic acids (3). Alkylation cannot be achieved with secondary halides. This procedure is not applicable to malonic acid itself. 

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