Alkenes dinitrogen trioxide

Pyrazine 1,4-dioxides are available by the direct self-condensation of 1,2-hydroxyaminooximes (70JOC2790). 1,2-Nitrooximes are obtained by the isomerization of alkene-dinitrogen trioxide adducts, which are reduced with palladium on charcoal to the hydroxyaminooximes which undergo acid-catalyzed auto-condensation to the pyrazine 1,4-dioxides (Scheme 19). 

The earliest reported Fxs were the result of the reaction of nitrous acid with naturally occurring alkenes being the identified intermediate a a-nitrooxime that suffers dehydration with cyclization. Apart from these conditions, the most recent Fxs synthesis descriptions have involved reactions between alkenes and dinitrogen trioxide (Fig. 3), nitroalkanes and aluminum trichlo-... 

Nitroso compounds are formed during the addition of nitrous oxide," " dinitrogen trioxide, and nitrosyl halides to alkenes, and in some cases, from incomplete oxidation of amines with peroxyacids like peroxyacetic acid. Quenching of carbanions with nitrosyl halides is also a route to nitroso compounds. A full discussion on this subject is beyond the scope of this work and so the readers are directed to the work of Boyer. ... 

Several nitrogen oxides dinitrogen trioxide, dinitrogen tetroxide and dinitrogen pentoxide can readily add to alkenes the resultant nitronitroso- dinitro- and... 

Pseudonitrosites and a-nitro ketone oximes were identified as intermediates in this process. This route has since been developed to provide access to mono- and poly-cyclic furoxans from readily-available alkenes and cycloalkenes. Treatment of the alkene with dinitrogen trioxide affords the nitro-nitroso adduct, which is readily isolated as its nitroso dimer (pseudonitrosite) thermal isomerization to the a-nitro ketone oxime, followed by dehydration with cyclization leads to the furoxan (Scheme 19). 

The reaction of alkenes with nitric oxide (NO), a mixture of nitric oxide and oxygen, or dinitrogen trioxide leads to /i-nitroso nitro compounds ( / -nitrosites or pseudo-nitrosites), which can convert to nitroso dimers79. Nitroalkenes are common byproducts in these reactions. The formation of /i-nitroso nitro compounds in the reaction between alkenes and nitric oxide is explained by the presence of nitrogen dioxide and dinitrogen trioxide in the nitric oxide. The reaction may be initiated by the attack of the N02 radical on the alkene to give a /i-nitroalkyl radical which then couples with nitric oxide. 

The type and the stereochemistry of the products depends on the structure of the alkene and the experimental conditions. The use of oxygen as a carrier gas for dinitrogen tetroxide affects the course of the reaction in various ways, depending on the alkene, but it especially prevents reduction of dinitrogen tetroxide to dinitrogen trioxide and thereby permits a cleaner product mixture to be obtained, or it can divert the reaction course toward the formation of /(-nitro nitrates115. 

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