Ninhydrin, oxidative degradations

Hydrolysis of the labeled compound with 2 N sulfuric acid furnished 3-amino-4-methyl-2-hexanone which, on treatment with iodine in the presence of sodium hydroxide, furnished isoleucine and iodoform. The iodoform was oxidized to carbon dioxide, while treatment of isoleucine with ninhydrin furnished 2-methylbutanal, isolated as its 2,4-dinitrophenylhydrazone. Kuhn-Roth oxidation of the aldehyde gave acetic acid which was degraded by the Schmidt procedure to carbon dioxide and methylamine. The 2-methylbutanal was also degraded stepwise by the method of Strassman. Determination of the radioactivity of the various degradation products showed that 94% of the activity was equally shared between the lactam C(2) and side-chain C(10) carbonyl atoms. The remaining activity was shared between C(4) of the lactam ring and the a> carbon atom of the ec-butyl side chain. The results are consistent with derivation of tenuazonic acid from isoleucine and two molecules of acetic acid. However, the direct incorporation of isoleucine into tenuazonic acid was not investigated. 

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