A nitrogen bound to both a good electrofuge and a good nucleofuge is known as a nitrenoid (for its resemblance to a nitrene). Nitrenes lack a full octet of electrons are thus highly electrophilic; nitrenoids exhibit analogous behavior and are often good substrates for electrophilic amination reactions. Nitrenoids can be generated from O-alkylhydroxylamines containing an N−H bond via deprotonation or from O-alkyloximes via nucleophilic addition. These intermediates react with carbanions to give substituted amines. Other electron-deficient, sp amination reagents react by similar mechanisms to give substitution products.
In aminations involving oxaziridines, nucleophilic attack takes place on the nitrogen atom of the three-membered ring. For some substrates (α-cyano ketones, for example), the resulting alkoxide reacts further to afford unexpected products. Straightforward β-elimination of the alkoxide leads to the formation of an amine.
Additions across pi bonds appear to proceed by typical nucleophilic addition pathways in most cases. Alkyl-, aryl-, and heteroaryllithium reagents add to azides to afford triazene salts. Reduction of these salts leads to amines, although they also may be converted to azides upon acidic workup with overall elimination of sulfinic acid.