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The reaction mixture should be cooled as soon as hydrogen decreases. Prolonged heating will often cause decomposition and loss of yield (73MI1). Higher reaction temperatures are required for diamination, however, yields are usually lower than for monoaminations (420R91). IV. The Chichibabin Reaction under Pressure Surprisingly, well-known Chichibabin reactions, conducted under typical heterogeneous conditions, often gave unexpected results when run under pressure. This phenomenon was discovered during an investigation of the amination of 3-picoline (83USP4386209).
Position 6 of 88 has a considerable positive charge; however, the 2- and 6-positions of 111 and 112 have acquired excess negative charge, making them unsuitable substrates for amination. NHka Pozharskii continued the investigation with dialkylaminopyridines (73CHE1119). No significant amount of 2-amino-6-dimethylaminopyridine was found, suggesting that the dimethylamino moiety is displaced prior to amination. It is interesting to find that 4-dimethylaminopyridine was aminated to 2-amino-4-dimethylaminopyridinesince it represents 40 CHARLES K.
Thus, at room temperature with potassium nitrate oxidant, 197 was obtained in 30% yield (68JOC1384), and the yield increased to 78% at 50°C (74YGK602; 75YZ1492). For 2,6-naphthyridine (184)and 2,7-naphthyridine (185),the C-1 a-adducts are both kinetically and thermodynamically stable (70JHC419; 8 1JHC 1349). At room temperature, 184was aminated with potassium amide and potassium nitrate in liquid ammonia in 54% yield, but the yield was only 18% from lowtemperature amination with potassium amide and potassium permanganate in liquid ammonia (Scheme 69).