26198-11-8

10439-77-7

1. Preparation of N-methyl-2-methyl-4-nitroaniline from N-formyl-2-methyl-4-nitroaniline: 18 g (0.1 mol) of N-formyl-2-methyl-4-nitroaniline was dissolved in 500 ml of dry tetrahydrofuran. 200 ml of tetrahydrofuran solution of 1 mole of borane/tetrahydrofuran complex was slowly added dropwise at 0 °C for 45 min. The reaction mixture was gradually warmed up to room temperature and subsequently refluxed for 1 hour. Upon completion of the reaction, the mixture was cooled to 0°C and hydrolyzed by adding 130 ml of water. Tetrahydrofuran was removed by evaporation and the residue was dissolved in 300 ml of 6N hydrochloric acid and refluxed for 2.5 hours. After cooling, the solution was poured into 1 liter of ice water and the yellow precipitate was obtained by filtration. The precipitate was washed with water, dried under reduced pressure at 50 °C and finally recrystallized from ethanol to give 15.8 g of N-methyl-2-methyl-4-nitroaniline (yield: 95%). The recrystallized product was suitable for further preparation of target compounds I-8.