Ethyl valerate reduction

DL-Isoleucine is synthesized in about 56% over-all yield by the method of Hamlin and Hartung (366). o-Oximino- -methyl-w-valeric acid (A) is prepared in 70% yield from ethyl sec.-bulyl acetoacetate, butyl nitrite and sulfuric acid. DL-Isoleucine is prepared in 80% yield by the reduction of (A) with hydrogen, palladium chloride and ethanol. This method is essentially the same as that originated by Bouveault and Locquin (117, 118, 525). By the comparable procedure of Feofilaktov (264, 265) the phenylhydrazone of methyl ethyl pyruvic acid, prepared from sec.-butyl acetoacetate and phenyldiazonium chloride (aniline and NaN02) in 68% yield, is reduced by means of rinc and alcoholic HCl to nearly the theoretical yield of a mixture of DL-isoleucine and DL-allo-isoleucine. Ehrlich (235) synthesized a mixture of isoleucine and allo-isoleucine from 2-methyl-n-butyraldehyde by the Strecker reaction. 

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