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Conducting the amination of 182 at room temperature in liquid ammonia with potassium nitrate as oxidant afforded a 56% yield of I94(68JOC1384). The amination of 1,8-naphthyridine (183) with potassium amide in liquid ammonia gave, according to NMR spectroscopy, the C-2 adduct (196)at -40°C and at +lO"C, indicating that this is both the kinetically and thermodynamically controlled product (8 1JOC2134). At - 40°C, oxidation with potassium permanganate afforded a 10% yield of 2-amino-1,8naphthyridine (197)(Scheme 68).
Work has also been done on the amination of alkoxypyridazines. Treatment of 3,6-dimethoxypyridazine (162) and 3-methoxypyridazine (163) with potassium amide in liquid ammonia, followed by the addition of potas- Sec. C] ADVANCES IN THE CHICHIBABIN REACTION 49 sium permanganate, afforded 4-amino-3,6-dimethoxypyridazine(164) and 4-amino-3-methoxypyridazine (165), respectively (86JHC621). The latter reaction gave 3,3'-dimethoxy-4,4'-bipyridazine(166) as a side product (Scheme 61). Substituted pyrimidines undergo amination when treated with potassium amide in liquid ammonia and oxidized with potassium permanganate.
Halogen derivatives of naphthyridines have also been found to undergo the Chichibabin reaction. When 5,8-dichloro-1,7-naphthyridine(200)was added to liquid ammonia containing potassium amide and followed with potassium permanganate, a 52% yield of 2-amino-5,8-dichloro-1,7-naphthyridine (201) was obtained (Scheme 70). Similarly, for the 5,8-dibromo derivative, the yield was 33% (83RTC359). Amination of 5-bromo- 1,7-naphthyridine with potassium amide in liquid ammonia gave a small yield of a normal Chichibabin product, 8-amino-5bromo- 1,7-naphthyridine, along with tele-aminated products 8-amino- and 2amino-l,7-naphthyridine.