Rearrangement of Some Oximes

It was discussed by Neber and co-workers (294-298) that some oximes (34) can be rearranged to a-amino ketones (36). The oxime was first converted into its /7-toluenesulfonic ester (35), which rearranged with sodium or potassium ethoxide to produce the amino ketone, which in most cases underwent further condensation to the dihydropyrazine (or pyrazine). The mechanism has been studied carefully in the reaction of 2,4-dinitrobenzyl methyl ketone and the unstable intermediate isolated from the reaction has been assigned (299, 300) the structure (37). The method was not always successful but literature preparations (294-298) are recorded in Table II.6. 

TABLE 11.6 REARRANGEMENT OF OXIMES TO PYRAZINES AND DIHYDRO-PYRAZINES 

Methyl o-nitrobenzyl ketoxime 2,5-Dimethyl-3,6-di(o-nitrophenyl)-3,6- dihydro 294,297 

Methyl phenethyl ketoxime 2 4-Dibenzy 1-3,6-dimethy 1-2,5 -dihydro 295 

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