The Schmidt reaction of some alphabeta-unsaturated ketones

Benzylideneacetone has been subjected to the Schmidt reaction in sulphuric acid under various conditions, and the only amide isolated was N-methylcinnamamide. Benzylideneacetons p-methoxy-, p-nitro- and m-nitro-benzylideneacetones were subjected to the Schmidt reaction in hydrochloric acid and in polyphosphoric acid. In hydrochloric acid each ketone gave a good yield of the N-methylcinnamamide. In polyphosphoric acid the nitrobenzylideneacetones gave a mixture of the N-styrylacetamide and the N-methylcinnamamide, benzylideneacetone gave mainly N-methylcinnamamide, only a trace of N-styrylacetamide being isolated in some runs of shortened duration, and the N-methylcinnamamide was the only amide isolated from p-methoxybenzyl-ideneacetone. The formation of aniline and p-anisidine during the reactions of benzylideneacetone and p-methoxybenzylidene-acetone in polyphosphoric acid has been explained. A mechanism has been proposed to explain the exclusive production of the N-methylcinnamamides in hydrochloric acid, and the novel variation of the amide ratio with solvent observed in the reactions with the nitrobenzylideneacetones. The Beckmann rearrangements of the alpha-oximes of benzylideneacetone, p-nitro- and m-nitro-benzylideneacetones have been re-examined. Methyl vinyl ketone, methyl isopropenyl ketone and mesityl oxide were subjected to Schmidt reaction conditions in hydrochloric acid. Ammonia was isolated from each reaction and, in addition methyl vinyl ketone gave diacetyl, methyl isopropenyl ketone gave methyl ethyl ketone, and mesityl oxide gave methylamine and acetone. Addition of hydrazoic acid to the olefinic bond of the ketones yielded azidoketones, decomposition of which in acids gave ammonia in each case, diacetyl and ethylenediamine from the azide of methyl vinyl ketone, shown to be 1-azidobutan-3-one, and methylamine from the azide of mesityl oxide. A mechanism for the decomposition of 1-azidobutan-3-one has been proposed.