Polyfluoroalkyl derivatives of nitrogen. Part 49. Ene reactions of trifluoronitrosomethane : formation of N-trifluoromethylhydroxylamines

Abstract

Trifluoronitrosomethane is a versatile and reactive enophile, forming N-alkenyl-N-trifluoromethylhydroxylamines, by transfer of allylic hydrogen to oxygen and bonding of olefinic carbon to nitrogen, with the olefins : propene, [1-²H]propene, but-1-ene, (E)-but-2-ene, 2-methylpropene, (Z)-pent-2-ene, 2-methylbut-1-ene, 2-methylbut-2-ene, (Z)-4-methylpent-2-ene, 2,3-dimethylbut-2-ene, cyclopentene, cyclohexene, 1-methylcyclohexene, ppinene, and allyl bromide, chloride, and cyanide. Cyclo-octa-1,5-diene gives an ene-adduct, while the initial ene-adduct from cyclohexa-1,4-diene undergoes rapid Diels–Alder addition of further trifluoronitrosomethane. Cyclohepta-1,3,5-triene undergoes Diels–Alder addition by way of its bicyclo[4.1.0]hepta-2,4-diene isomer. Acetylacetone givesthe compound CF₃·N(OH)·CH(CO·CH₃)₂. In these ene reactions, nitrogen becomes bonded to the least substituted carbon atom. At –78 °C, the following relative rates of reaction were observed:[graphic omitted].

The hydroxylamines are easily oxidised to nitroxides, and those from the compound CF₃·N(OH)·CMe₂·CMe:CH₂ and its reduction product, CF₃·N(OH)·CMe₂·CHMe₂, are stable; their ¹H n.m.r. spectra have been examined.