Phthalimido Malonic Ester

Phthalimide, 2, 75 7, 8, 78 Phthalimide synthesis, 7, 78 Phthalimido Malonic Ester, 7,78 Picric acid, 4,16... 

Just as the malonic ester synthesis gives substituted acetic acids, the A/-phthalimidoma-lonic ester synthesis gives substituted aminoacetic acids a-amino acids. A-Phthalimido-malonic ester is alkylated in the same way as malonic ester. When the alkylated A-phthalimidomalonic ester is hydrolyzed, the phthalimido group is hydrolyzed along with the ester groups. The product is an alkylated aminomalonic add Decarboxylation gives a racemic a-amino add. 

Method Nine, Booth et al. (114). Methionine is prepared in 40% overall yield from -chloroethylmethyl sulfide by, a modification of the phthalimido-malonic ester reaction of Barger and Weichselbaum (67, 68). According to Snyder et al. (739), 5% of pseudomethionine (two molecules of methionine joined by the loss of two hydrogen atoms) is present in methionine prepared by large-scale adaptation of the Barger-Weichselbaum synthesis. 

Carboxylic acids from malonic acid esters via malonic acids. A suspension of ethyl a-carbethoxy-y-oxo-5-phthalimidovalerate in 48%-HBr allowed to stand at room temp, overnight, then heated on a steam bath until dissolved, allowed to cool, and evaporated to dryness in vacuo a-carboxy-y-oxo-<5-phthalimido-valeric acid (Y 83.0%) heated to 170 /3-4 mm until gas evolution ceases -phthalimidolevulinic acid (Y 90.7%). D. P. Tschudy and A. Collins, J. Org. Chem. 24, 556 (1959). 

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