OXIDATIVE ADDITION-REACTIONS OF OMEGA-ALKENYL NITRONATE ANIONS

Anions are oxidatively added to nitronate anions to yield alpha-substituted nitroalkanes when potassium hexacyanoferrate(III) is used as oxidant. Oxidation of nitronate anions yields intermediate alpha-nitroalkyl radicals, which undergo addition by anions to give intermediate alpha-substituted nitroalkane radical anions, which are further oxidised to yield the alpha-substituted nitroalkanes. The nitronate anions used are derived from 5-nitrohex-1-ene, 6-nitrohept-1-ene, endo-5-nitro-exo-6-phenylbicyclo[2.2.1]-hept-2-ene, and 1-(bicyclo[2.2.1]hept-5-en-endo-2-yl)-2-nitropropane. The intermediate alpha-nitroalkyl radicals underwent addition of anions to form radical anions faster than intramolecular cyclisation onto the omega-alkenes. The alpha-nitroalkyl radical derived from 1-(bicyclo[2.2.1] hept-5-en-endo-2-yl)-2-nitropropane underwent cyclisation when the oxidation was carried out in the absence of an added anion. The addition of anions (thiocyanate, benzenesulfinate, 4-chlorobenzenethiolate, and nitrite) to the alpha-nitroalkyl radicals derived from endo-5-nitro-exo-6-phenylbicyclo[2.2.1]hept-2-ene occurred stereoselectively from the less hindered exo face. Oxidative addition of 4-chlorobenzene-thiolate to the nitronate from endo-5-nitro-exo-6-phenylbicyclo[2.2.1]hept-2-ene gave an unusual cyclisation via addition of a thiyl radical to the alkene.