Radicals nitrosoamides

Amidyl Radical Cyclizations from A-Halo- and A-Nitrosoamides. 35... 

Similar reactions occur with TV-nitrosoamines R2-NNO and /V-nitrosoamides RC0(R )NN0.70 Apart from the intramolecular hydrogen atom transfer, diverse intramolecular radical additions (cyclizations) and other rearrangements have also been used to obtain cross-reaction products between NO and the radicals resulting from the transformation of the primarily formed R to another radical R. 69 70 Giving evidence for the persistent radical effect, the yields of the desired products are large and those of the selftermination of the transient intermediates are low,... 

Other methods, among which thermolysis or photolysis of tetrazene [59], photolysis of nitrosoamines in acidic solution [60], photolysis of nitrosoamides in neutral medium [61], anodic oxidation of lithium amides [62], tributylstannane-mediated homolysis of O-benzoyl hydroxamic derivatives [63, 64], and spontaneous homolysis of a transient hydroxamic acid sulfinate ester [65] could have specific advantages. The redox reaction of hydroxylamine with titanium trichloride in aqueous acidic solution results in the formation of the simplest protonated aminyl radical [66] similarly, oxaziridines react with various metals, notably iron and copper, to generate a nitrogen-centered radical/oxygen-centered anion pair [67, 68]. The development of thiocarbazone derivatives by Zard [5, 69] has provided complementary useful method able to sustain, under favorable conditions, a chain reaction where stannyl radicals act simply as initiators and allow transfer of a sulfur-containing... 

The initial rate for the accumulation of C=0 groups of nitrosoamides in the NO concentration range of 4 x 10 - to 4 x 10 mol/1 is proportional to [NO ]", where n 2. This fact confirms the participation of nitrosyl nitrate in PCA conversions. In reaction (Equation 7.42), an unstable intermediate nitrite is initially generated. The latter gives the detectable acylalkylaminoxyl radicals with an anisotropic triplet spectrum (.<4 =1.94 mT, gj, = 2.003) (Figure 7.7). 

The known free-radical decomposition of aryl nitrosoamides (ArN(NO)COR ) and the report that nitrosoamides of 0-alkyl-hydroxylamines decompose by a free-radical pathway indicate that free-radical processes might occur in the normal nitrosoamide decomposition. In fact, the aliphatic nitrosoamides have been used as initiators at elevated temperatures for the polymerization of styrene and other olefins At, or near, room temperature, however, it appears that free radicals are not formed in the nitrosoamide decomposition. It has been found, for example, that (1) COj (a product of the decarboxylation of carboxyl radicals) is not formed in the decomposition (2) the scavenger nitric oxide has no effect on the reaction (3) normal products and no polymer are formed in the decomposition of A -(i-butyl)-A -nitrosobenzamide ° ° and N-nitroso-7V-(l-phenylethyl)acetamide -in styrene and (4) no difference in acetate yields is observed when A -nitroso-A-(1-phenyl-ethyl) acetamide is decomposed in benzene in the presence or absence of 0-1 m Styrene and 1-phenylethyl acetate react with... 

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