Methylamino radical

Dimethylamino. There are many more known sources of this radical than of the methylamino radical. Photolysis of dimethyl- and trimethylamine yields the radical by Reactions 10 and 11... 

The partial rate factors and the isomer distribution in the amination by di-methylamino radical cation of toluene, isopropylbenzene, -butylbenzene, biphenyl and naphtalene are reported in Table 7. These partial rate factors are far the highest ever observed in homolytic substitutions so that the general character of the homolytic amination allows a more relevant analogy to be drawn with the electrophilic substitutions than with the homol5rtic arylation, the only homol5rtic substitution for which numerous and accurate quantitative data exist in homo-cyclic aromatic series. 

Distortion of the chair conformation by substitution occurs in 2,2,6,6-tetramethyl-piperidin-4-one hydrochloride (45) (71AX(B)932), in which steric interaction between axial methyl groups leads to flattening of the ring. The resultant C(2)—C(6) intramolecular distance is 3.2 A, to be contrasted with 2.4 A in the non-methylated compound. A similar effect is to be found in other 2,2,6,6-tetramethyl derivatives (81AX(B)1771). In the related free radical nitroxide (46) the steric interactions are reduced by adoption of a symmetric twist chair form (74AX(B)790). 4-Chloro-5-methylamino-2,3,6-pyridinetrione monohydrate... 

Aminopyrazolo[3,4-d]pyrimidines 257 were converted into the corresponding 4-aryl substituted derivatives 259 via treatment with alkyl nitrites and boiling in aromatic solvent. The isomer distribution of 259 prepared by these route was that predicted for a radical intermediate (ortho, meta, and para). The structure of isomers was established by H-NMR. Unusual fragmentation products were isolated these probably result from collapse of the radical intermediate 258 (83JOC4605). Methylation of 257 takes place at either N-1 or N-2. Further methylation affords methylamino derivatives structures of the products were established by C-NMR as well as by chemical methods (75JOC1822). 

Preparation method of the chromophore involves the condensation of para-nitroaniline with thiocyanate in methanol and the bromine radical cyclization using bromine in acetic acid. In this case only one product - 2-(methylamino)-6-nitroben-zothiazole - was obtained, which is easily purified over column chromatography using neutral alumina [589],... 

The +NR+ spectrum of 8 showed a small survivor ion, but differed substantially from the spectra of other C2H5NO isomers, e.g., 6, 7, AT-methylamino(hy-droxy)carbene (9), and N-methylformamide (10). The low intensity of survivor ions in the NR mass spectra of enol imines is due to Franck-Condon effects in collisional reionization that result in vibrational excitation of the resulting cation radical followed by dissociation. Franck-Condon effects were studied for collisional ionization of acetimidic acid, CH3C(OH)=NH, which was one of the neutral dissociation products of 1 -hydroxy- 1-methylamino-l-ethyl radical, a hydrogen atom adduct to AT-methylacetamide [37]. The cation-radical dissociates extensively upon reionization, and the dissociation is driven by a 74 kj mol-1 Franck-Condon energy acquired by vertical ionization. 

For the hydrogenation of the racemic a-(A -benzoyl-/V-methylamino)propiophenone, (Scheme 9) polymers eontaining A-substituted DPEN were prepared by radical copolymerization of (R,R)-9 (Scheme 3) with various crosslinking agents (Scheme 10) [16]. 

Based on the early studies of radical generation from organotin hydrides and their addition to multiple bonds [1-3], particnlarly in cyclization [4-7], several groups applied this chemistry to the synthesis of indoles and indolines. For example, in 1975 Beckwith and colleagues found that < -(A -allyl-Af-methylamino)iodobenzene was converted to 1,3-dimethylindoline (78% yield) upon treatment with tri-n-butylstannane (prepared by the reduction of tri-n-butyltin chloride with LiAlH ) in the presence of AIBN (azobisisobutyronitrile) and benzene at 130°C in a sealed tube [4],... 

Balcerczyk, A. Soszynski, M. Bartosz, G. On the specificity of 4-amino-5-methylamino-2, 7 -difluoro-fluorescein as a probe for nitric oxide. Free Radical Biol Med. 2005, 39, 327-335. 

Proposals for the mechanism of PPS formation include nucleophilic aromatic substitution (Sj Ar) (2radical-cation (27), and radical-anion processes (28,29). Some of the interesting features of the polymerization are that the initial reaction of the sodium sulfide-hydrate with NMP affords a soluble NaSH-sodium 4-(N-methylamino)butanoate mixture, and that polymers of higher molecular weight than pi edicted by the Caruthers equation are produced at low conversions. Mechanistic elucidation has been hampered by the harsh polymerization conditions and poor solubility of PPS in common organic solvents. A detailed mechanistic study of model compounds by Fahey provided strong evidence that the ionic S]s Ar mechanism predominates (30). Some of the evidence supporting the S s(Ar mechanism was the selective formation of phenylthiobenzenes, absence of disulfide production, kinetics behavior, the lack of influence of radical initiators and inhibitors, relative rate Hammet values, and activation parameters consistent with nucleophilic aromatic substitution. The radical-anion process was not completely discounted and may be a minor competing mechanism. 

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