Ketoximes from nitro compounds

Nitration studies on a series of 3-methyl- and 3-ethylindoxazenes have been recorded.12 3-Methyl- and 3-ethylindoxazene yield a mixture of the 5-nitro and 5,7-dinitro derivatives. If the 5-position is blocked (e.g., by chloro or alkyl groups) then, surprisingly, nitration takes place at the 4-position. As expected, the 7-chloro-3-alkyl and the 3,7-dialkyl derivatives are nitrated exclusively at the 5-position, whereas the 3,6-dialkyl and 3-alkyl-6-chloro derivatives yield a mixture of the 5-nitro and 5,7-dinitro compounds. The structures of the nitro compounds were confirmed by H-NMR spectroscopy and, in some instances by synthesis from the nitro-substituted ketoxime acetates (see Section II,A,2). 

The nitroparaffins are condensed with aldehydes to yield nitro alcohols (70-80%), which on acetylation and treatment with an aqueous methanolic solution of sodium bicarbonate are converted to nitroolefins (80-84%). These compounds are reduced to the corresponding ketoximes by zinc and acetic acid (50-60%). Reduction with iron and dilute hydrochloric acid gives good yields of either ketones or ketoximes, depending upon the amount of hydrochloric acid used. The ketoximes can be hydrolyzed to ketones by refluxing with dilute sulfuric acid in the presence of formalin, which acts as a hydroxylamine acceptor (80%). The over-all yields from the nitroolefins are 40-60%. In this manner, certain otherwise difficultly obtainable ketones are prepared. Semicarbazones have been converted to ketones by treatment with sodium nitrite in glacial acetic acid, with aqueous oxalic acid, or with phthalic anhydride. ... 

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