Nitrosyl formate

For nitrosyl chloride (Entry 8) and nitrosyl formate (Entry 9), the electrophile is the nitrosonium ion NO+. The initially formed nitroso compounds can dimerize or isomerize to the more stable oximes. 

Nitrosyl formate may be generated in situ by treating isopentyl nitrite with anhydrous formic acid. This reagent evidently adds to olefins such as cyclohexene, styrene, norbomene, trans-3-hexene, and 2,3-dimethylbutene to give nitrosoformates. While the first three olefins were converted into dimeric products, 2,3-dimethylbutene produced a 50-50 mixture of the monomer and the dimer (as a blue oil). The product of the reaction with trans-3-hexene contained some of the corresponding oximino formate. 

Nitrosyl formate, 406 Nitrosylsulfuric acid, 388 preparation of, 389 Nitrous acid, acid strength, 388 NNO Convention, 345 Nomenclature of azo compounds, 289 of azoxy compounds, 345-346 of C-nitroso compounds, 387 NON Convention, 346... 

A number of reactions have been reported which occur at coordinated nitrogen-containing groups and lead to the isolation of nitrosyl complexes these will now be considered. Electrophilic attack at a nitro group, leading to nitrosyl formation, has been reported (see equation 11).M... 

Nitrosyl formate, generated in situ from 3-methylbutyl nitrite in excess formic acid, underwent addition in a trans manner to cyclohexene to yield 1,1 -azobisi7ra .v-2-l ormyloxycyclohexane) A, Af-dioxide (1) in satisfactory yield70. The trans configuration was demonstrated by reduction to /nmv-aminocyclohcxanol as the hydrochloride salt (2-HCl), identified by comparison with an authentic sample. Saponification of the formyl-nitroso dimer afforded l,l -azabis(fraiw-2-hy-droxycyclohexane) A, A"-dioxide in 92% yield. 

The steric course of additions of amines and alcohols to acetylene dicarboxylic ester was studied under various conditions. Secondary amines gave stereospecifically cis addition product. Nitrosyl formate can be generated in situ in the presence of an olefin to yield the nitrosoformate which on hydrolysis affords the hydroxynitroso compound in high yield. Transoximination gave the a-hydroxy ketone. Phosphorous tribromide can be added to olefins to yield 1 1 adducts with uv irradiation, peroxides, or heat as initiators ... 

Tocheva El, Rosell FI et al (2007) Stable copper-nitrosyl formation by nitrite reductase in either oxidation state. Biochemistry 46 12366-12374... 

A soln. of cyclohexene in isoamyl nitrite added at 5° with vigorous stirring during 2 hrs. to formic acid m 5 -l-formoxy-2-nitrosocyclohexane dimer. Y 59%. -Nitrosyl formate is prepared in situ. F. e. s. H. C. Hamann and D. Swern, Am. Soc. 90, 6481 (1968). 

Under nitrite-limited conditions, an increased catalytic activity occurred at -105 mV, close to the reduction potentials of heme 1 and 3 ca. -107 mV) and decreased ca. -320 mV, possibly due to a conformational change caused by reduction of hemes 4 and/or 5 ca. -323 mV), or inhibition due to ferrous nitrosyl formation . As the concentration of nitrite increased, the catalytic peak broadened and moved toward a lower potential under these enzyme-limited conditions. 

Beyond these general characteristics of electrophilic addition, certain of the reagents shown in Scheme 4.4 exhibit special features which should be noted. The addition of nitrosyl chloride or nitrosyl formate to alkenes is accompanied by subsequent reactions if the nitroso group is not tertiary. The nitroso compound may dimerize or rearrange to the more stable oxime tautomer. 

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