1(2H)-Isoquinolinone, 3,4-dihydro-5-methyl-

24644-78-8

129075-56-5

General procedure for the synthesis of 5-methyl-3,4-dihydroisoquinolin-1-one from 4-methyl-2,3-dihydro-1H-inden-1-one: 4.7 g (32.2 mmol) of 2,3-dihydro-4-methyl-1H-inden-1-one was mixed with 53 g of trichloroacetic acid and heated to 65°C. To the reaction mixture was added 4.2 g (64.4 mmol) of azide Sodium azide was added to the reaction mixture and the reaction was kept at 65°C for 18 hours. Subsequently, 1.0 g of sodium azide was added and heating was continued for 4 hours. After completion of the reaction, the mixture was diluted with 200 ml of ice water and extracted with ether. The ether extract was washed sequentially with water and saturated sodium bicarbonate solution, dried over anhydrous magnesium sulfate and concentrated. The residue was purified by silica gel column chromatography (eluent: ether to ether/methanol 95/5). The resulting product was recrystallized from toluene to give 2.45 g (47% yield) of the target compound with a melting point of 141°C-143°C.