General procedure for the synthesis of N-(2-dimethylphenyl)-2-piperidinecarboxamide from N-(2-dimethylphenyl)pyridine-2-carboxamide: Example-2 Preparation of pyridine-2-carboxylic acid-2',6'-dimethylphenylamine; To a stainless steel reaction flask equipped with a mechanical stirrer were added 25 g of pyridine-2-carboxylic acid-2',6'-dimethylphenylamine, 625 ml methanol, 63 ml acetic acid and 15 g of Raney nickel. Subsequently, argon was passed into the mixture for 5 minutes to displace the air, the reaction flask was sealed and charged with 18 kg/cm2 (260 psi) of hydrogen. The reaction mixture was heated to 50°C and maintained at the same pressure and temperature for 28-30 hours until the reaction was complete. After completion of the reaction, the reaction mixture was filtered to remove the catalyst and the filtrate was concentrated in a rotary evaporator. The crude product was dissolved in 250 ml of toluene, transferred to a partition funnel, 250 ml of water was added and alkalized with 50 ml of 20% aqueous sodium hydroxide. The organic layer was separated and the aqueous layer was extracted twice with 100 ml of toluene. The organic layers were combined and dried with anhydrous magnesium sulfate and subsequently concentrated in a rotary evaporator. The resulting crude solid was recrystallized with 70 ml of toluene to give 18.5 g of slightly pink piperidine-2-carboxylic acid-2',6'-dimethylbenzenemethanamine solid in 72% yield with a melting point of 115.7-116.2 °C. 1H NMR (CDCl3, 300 MHz): δ=8.31 (s, 1H), 7.00 (m, 3H), 3.32 (dd, J=3.2 ,9.7Hz, 1H), 3.0 (m, 1H), 2.68 (m, 1H), 2.14 (s, 6H), 1.98 (m, 1H), 1.93 (s, 1H), 1.77 (m, 1H), 1.59-1.50 (m, 2H), 1.47-1.37 (m, 2H) ppm; 13C NMR (CDCl3, 75MHz) : δ=172.1, 134.7, 133.4, 127.6, 126.5, 59.9, 45.3, 30.0, 25.6, 23.6, 18.1 ppm.
