C–N Bond Formation by the Oxidative Alkylamination of Azines: Comparison of AgPy 2 MnO 4 versus KMnO 4 as Oxidant

Reports on the successful oxidative alkylamination of azines by the S N H ‐reaction, with the use of alkylamines other than methylamine, are very scarce. Hitherto, the experimental limitation to extend oxidative amination of azines with NH 3 /KMnO 4 to oxidative alkylamination is solely ascribed to the low solubility of KMnO 4 in alkylamines and the increased sensitivity of alkylamines towards oxidation in comparison with ammonia. Our experimental data for the first time prove that there is also a substrate dependence in this type of reaction. 2‐Alkylamino‐5‐nitropyridines and 4‐alkylaminoquinazolines were smoothly obtained by the treatment of 3‐nitropyridine and quinazoline, respectively, with alkylamine/AgPy 2 MnO 4 . Although KMnO 4 still gives moderate to good results with 3‐nitropyridine, it is completely useless for reactions with quinazoline with the same alkylamines. The use of AgPy 2 MnO 4 was found to give equal or superior results to those of KMnO 4 depending on the alkylamine and the substrate used and therefore seems to be a promising general oxidant for successful oxidative alkylaminations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)