Liquid ammonia-potassium permanganate

As discussed before, in liquid ammonia/potassium permanganate nucleo-phugal substituents at C-2, such as ones present in the naphthyridines (84c, 84e, 84h, 84i, 841, and 84m), could not be replaced by the amino group only SnH substitution takes place. However, it has been observed that in the reaction of the 2-chloro-3-nitro-l,8-naphthyridine (92c) with liquid methylamine/potassium permanganate S H substitution as well as methylamino-dechlorination takes place, yielding 2,4-bis-(methylamino)-3-nitro-l,8-naphthyridine (93c). 

An unusual ring contraction of 1,6- and 1,7-naphthyridinium salts was observed when treated with liquid ammonia/potassium permanganate (85JOC3435). Thus, 163 gave the azaindolone 164, whose structure was confirmed by X-ray analysis, and 165. 

Oxidative amination of 4-nitropyridazine does not require the use of potassium amide. With liquid ammonia/potassium permanganate at —45 °C 5-amino-4-nitropyridazine is obtained, although, in a rather low yield (88JHC831). The 3-aryl- and 3,6-diaryl-4-nitropyridazines are however aminated in very high yield into the corresponding 5-amino compounds (Scheme 26). 

As expected 3-aminocarbonyl-l,6-dimethylpyridinium iodide does not undergo imination in liquid ammonia/potassium permanganate, as position 6 is blocked for addition. Surprisingly, however, an oxo-demethylation... 

Amination of azaaromatic compounds using liquid ammonia-potassium permanganate (85S884 86MI1) has been found to be a successful method for preparing a number of 5-amino-l,2,4-triazines (Scheme 73). This SNH reaction is based on the ability of 3- and 6-substituted triazines to form amino adducts 22 at C-5 in liquid ammonia (see Section III,A,2 and Scheme 18). These adducts can be oxidized into 5-amino-1,2,4-triazines 126. A number of 1,2,4-triazines containing substituents at C-3 and C-6,... 

The amination of quinazoline (241) with sodium amide in DMA has been described to give 4-aminoquinazoIine (242) in 40% yield (60YZ245). In the potassium amide/liquid ammonia/potassium permanganate system of van der Plas, quinazoline gave 62% 242 and 2% 4,4 -diquinazolylamine (243) (Scheme 80) (82JHC1285). 

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... 

The NMR spectrum of 1,7-naphthyridine in liquid ammonia/potassium amide at —40°C showed the presence of the C-2 and the C-8 a-adducts. Increasing the temperature of this mixture from —40°C to +10 °C the mixture irreversibly converts into the C-8 adduct. Addition of potassium permanganate gives 8-amino- 17-naphthyridine. The allylic contribution in the C8-adduct accounts for its higher stability. 

In a Chichibabin-type reaction (see Section 2.4.2), quinoline reacts with potassamide (KNH2) in liquid ammonia at -70 °C to give 2-amino-1,2-dihydroquinoline and this is oxidized by potassium permanganate [manganate(VII)] at the same temperature to yield 2-aminoquinoline (Scheme 3.6). If the temperature is allowed to increase to -45 °C the adduct rearranges into 4-amino-1,4-dihydroquinoline, and upon oxidation this product gives 4-aminoquinoline. 

H. C. van der Plas, Janssen Chim. Acta 3, 23-28 (1985) . .Potassium Permanganate in Liquid Ammonia a Useful Reagent for Chichibabin Animation". 

In the animation of quinoline in liquid ammonia, the initially formed cr-complex (242) on heating is fully isomerized to the more stable cr-complex (243). This transformation is used in preparative work. Adding potassium permanganate to the cr-complex formed under kinetic or under thermodynamic control allows either 2-amino- or 4-amino-quinoline to be obtained in good yield. 

Chichibabin amination refers to a reaction in which a hydrogen of an azaheteroarene is replaced by an amino group. The reaction is usually carried out by heating the heterocycle with a metal amide at elevated temperatures in an aprotic inert solvent. Potassium amide or sodium amide in liquid ammonia have also been found to be appropiate reagents for amination the presence of an oxidant seems to promote the reaction. Potassium nitrate is usually employed as an oxidant, 9 16 but other work shows that potassium permanganate can also successfully be used as an oxidizing agent in liquid ammonia.IO-20 17... 

Other work has been carried out concerning the amination of 3-nitro-1,5-naphthyridine (46a) with liquid ammonia containing potassium permanganate.27 The 4-amino-3-nitro- 1,5-naphthyridine (50) is obtained in 50% yield. Its precursor, the covalent rr-adduct (47a), has been detected by NMR spectroscopy (see Section II,B,3). 

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