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A number of nitrosonium and nitronium salts were probed as reagents for the heterocyclization of 1-bromo-1-fluorocyclopropanes in the presence of organic nitriles to give pyrimidine N -oxides. Nitronium triflate, either preformed or generated in situ from nitric and triflic acids, was shown to be the most efficient reagent for this reaction, affording a mild and convenient procedure for the synthesis of 4-halogenopyrimidine derivatives. X-ray crystallography was used to confirm the ionic structure of nitronium triflate (NO 2 + )(CF 3 SO 3 − ).

An efficient aza-Diels–Alder reaction of N-arylimines with N-vinylpyrrolidinone was achieved using nitrosonium tetrafluoroborate as a cation radical initiator, giving cis-4-(2-oxopyrrolidin-1-yl)tetrahydroquinolines in various yields.

A 2:1 mixture of chlorotrimethylsilane and sodium nitrite or nitrate was found very effective for deoximation. Trimethylsilyl nitrate or nitrite seems to be initially formed, which further reacts with chlorotrimethylsilane to produce a nitrosonium or nitronium chloride. The deoximation reaction can also be successfully performed by t-butyl nitrite and chlorotrimethylsilane.

Peroxynitrite (ONOO − ) has been found to react with the title amine 1 and quinone 5 to form N -nitrosoamine 2 and 2,3-epoxide 6 , respectively, in accord with the in situ generation of the nitrosonium and hydroperoxide ions as the respective reactive species.

Anilines were easily diazotized and efficiently converted to aryl halides in an one-pot reaction using sodium nitrite and halotrimethylsilane in carbon tetrachloride. Halotrimethylsilanes are used for both generating nitrosonium donor from sodium nitrite, and the halogen substitution of diazonium group.

Oxidation of tetrakis-diethylaminocyclopentadienone iron tricarbonyl (1) electrochemically or with nitrosonium hexafluorophosphate afforded the dication of tetrakisdiethylaminocyclopentadienone (3). Oxidation of 1 with bromine and aqueous workup gave diethylaminocyclobutenedione-N,N-diethylcarboxamide (4), which was also formed by the hydrolysis of 3. The structures of the products were confirmed by X-ray crystallography.

Simple Hammett studies, hydrogen isotope effects, and attempted preparation of proposed transient intermediates are used to probe the mechanism of oxidation of alcohols by 2,2,6,6-tetramethylpiperidine nitrosonium ion.

Reactions of nitrosonium hexafluorophosphate or tetrafluoroborate with olefins having aryl groups at an olefinic carbon atom at low temperature in acetonitrile afforded 4H-5,6-dihydro-1,2-oxazines with two aryl groups at C-4 and C-6 in fair to good yields.