Reactions

First, hydroxylamine and the ketone (or aldehyde) react to form an oxime, following the same mechanism described for imine formation. The latter is then protonated, converting the hydroxyl group into a good leaving group. Then, the group in the anti position relative to the leaving group migrates from the carbon to the nitrogen atom, simultaneously with the departure of a molecule of water. A water molecule subsequently attacks the resulting nitrilium ion, forming a tetrahedral intermediate. After successive deprotonation and proton transfer, the amide is recovered from this intermediate.