Oxidation amide ions

The amination of 2-chloropyridine-A-oxide (53) with potassium amide in liquid ammonia yielded a mixture of 2-(55) and 3-amino-pyridine-A-oxide (56) in 5-10% total yield.This rearrangement might be explained by an aryne mechanism involving 2,3-pyridyne-A-oxide (54). Since the structure of 56, with its quaternary nitrogen atom, is more analogous to that of 3-methoxybenzyne (39) than to that of 2,3-pyridyne (26), an orientation effect directing the amide ion to C-3 can be expected here. 

Nitrosamines [115] probably afford the amide ion and nitrogen oxide. The latter accepts the second electron and is converted to hyponitrite ion ... 

Intermolecular animations of pyridine 1-oxides with amide ions have not been as well investigated as those of the neutral molecules. Most of the examples studied involve halo Af-oxides, where a competition between Type B behaviour and pyridyne reaction compete (Scheme 91) (67RTC655). 

With pyridine 7V-oxides the situation is reversed in that amide ion reacts at the 4-position by the AE mechanism but at the 2-position by the EA mechanism, albeit in poor yield (Scheme 137) (67RTC655). 

By the action of phenyllithium, pyridazine is converted to adduct 100 (Table XVI), resulting from nucleophilic attack at position 3.34 The structural assignment is based upon H- and 13C-NMR, starting with pyridazine and its 4,5-dideutero derivative. The site of attachment of the phenyl group is other than that observed with the amide ion in ammonia (C-4). Analysis of the products obtained after hydrolysis and oxidation indicates the presence of nearly 5-6% of 4-phenyIpyridazine. Although this finding implies the formation of a small amount of the isomeric adduct 101, there is no NMR evidence for it. However, both isomeric adducts can be detected when the reaction is carried out in the presence of TMEDA or tetrahydrofuran at a lower temperature. The chemical shift values of adduct 101 are closely similar to those of the amino analog 29. 

The oxidative amination procedure is simple, but varies depending on the structure of the substrate. The substrate is dissolved in liquid ammonia, containing the potassium amide, reacted for a short time, after which the potassium permanganate is added. The reaction is completed by adding ammonium chloride to decompose the amide ion. The ammonia... 

The mechanistic role of the oxidant can be understood as follows. After addition of the amide ion to the azine (for example pyrimidine in Scheme 2) an anionic a-adduct is formed, which is quite stable in this polar medium, as shown by NMR spectroscopy (see Section IY.A). 

In the oxidative amination of quinoline, using potassium amide in liquid ammonia and permanganate as oxidant, it was found that the site of ami-nation is strongly depending on temperature. When the amination is carried out at — 65 °C 2-aminoquinoline is isolated (52%) 4-aminoquinoline is formed (with some 2-aminoquinoline) when the amination is performed at room temperature. By NMR spectroscopy it was unequivocally observed that at — 65 °C addition of the amide ion occurs at position 2 of the quinoline ring, yielding the a-adduct 2-amino-1,2-dihydroquinolinide, which under the conditions of the reaction remained stable. When warming up the solution this C-2 adduct irreversibly converts into the... 

Nitropyridazine Af-oxides readily form (T-complexes (e.g., 205) in liquid ammonia in the absence of free amide ion.355 The activating effect of the... 

Another interesting sequence is the amidoselenenation of alkenes for the synthesis of allylic amides. The seleniranium ion is trapped by a nitrile group which is first converted to an iminium chloride and then hydrolyzed to the amide (similar to the Ritter amide synthesis). Several differing nitriles (e.g. methyl to phenyl) have been utilized and all provide good yields of amides. The stereochemistry of addition is always trans but mixtures of regioisomers occur with terminal and unsymmetrically substituted oleflns (equation 24). The -seleno amide is easily converted to the allylic amide by oxidation of the phenyl selenide using the standard conditions. ... 

Thus, oxide ions or amide ions cannot exist in measurable concentrations in water because the reactions... 

Lithium 1,2-dialkyl-1-(4-pentenyl)amide ions obtained from secondary pentenyla-mines may be anodically oxidized to form aminyl radicals which undergo cyclization to give regio- and stereoselectively c/5 -A/ -alkyl-2,5-disubstituted pyrrolidines [26] ... 

The last three, the NH2, NH , and N ions, are found in the salt-like amides, imides, and nitrides of the most electropositive metals, but with the exception of the amide ion the stereochemistry of nitrogen is based on N with no lone pairs and N with one lone pair. These two states of the nitrogen atom correspond to the classical trivalent and pentavalent states, now preferably regarded as oxidation rather than valence states. 

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