Ethyl 2-methyl-2-ethylmalonic acid

EHsubstituted (—)-a-methyl-a-ethyl-]3-thiolactone (IX) was synthesized by Jerman and Fles [7 ] from (+)-methyl-ethylmalonic acid monoethyl ester (V), which was prepared by fractional crystallization of diastereomeric quinine salt for the (+)-antipode and cinchonidine salt for the (—)-antipode. Monoester (V) was converted to a-methyl-a-ethyl-/3-bromopropionic acid (VI) using essentially the method described by Sweeney and Casey [4] for the racemic compound. Optically active a-methyl-a-ethyl-j3-fiiiolactone (IX) was synthesized either via the dehydration of the /3-mercapto derivative (VII) or by debenzylation of the jS-benzyl-... 

The diazo compound from methyl benzoylacetate gives phenylcarbo-methoxyketene in 70% jdeld when the final decomposition is carried out in refluxing xylene, but it is converted largely to the ester of phenyl-malonic acid by heating in the absence of a solvent. The ethyl ester of ethylmalonic acid is the principal product from the decomposition (in the absence of a solvent) of the diazo compoimd obtained from ethyl pro-pionylacetate. A small amoimt of the ketene evidently was formed also. The diazo compound obtained from ethyl ethoxalylacetate on decomposition in warm xylene gives 54% of dicarbethoxyketene. ... 

Fig. 14.2 Chromatogram of organic acids extracted using ethyl acetate and diethyl ether and separated as their methyl esters (diazomethane) on 5 per cent OV-1 using temperature programming from 70°C to 300°C at 4°C min Peak identifications are 1, ethylmalonate 2, methylsuccinate 3, adipate 4, hexanoylglycine 5, hippurate 6, n-pentadecanoate (internal standard). (Redrawn with modifications from Mantagos et al., 1979)...

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