General procedure for the synthesis of 7-nitro-3,4-dihydro-2H-1-naphthalenone from 1-tetralone: Concentrated sulfuric acid (60 mL) was cooled to 0 °C in an ice bath. 1-Tetrahydronaphthalenone (8 g, 54.7 mmol) was added with stirring, and then potassium nitrate (6 g, 59.3 mmol, 1.08 eq.) dissolved in concentrated sulfuric acid (18 mL) was slowly added dropwise through a dropping funnel, controlling the reaction temperature to no more than 15 °C. The reaction was carried out at a controlled temperature of 15 °C. The reaction was completed with the addition of potassium nitrate (6 g, 59.3 mmol, 1.08 eq.). After the dropwise addition was completed, the reaction mixture was continued to be stirred for 1 hour. The reaction was quenched by pouring the reaction solution into crushed ice, the precipitate was collected by filtration and washed with distilled water. After drying, recrystallization was carried out through a solvent mixture of ethanol/water (1:1) to give 7-nitro-3,4-dihydro-2H-1-naphthalenone (8.5 g, 81% yield) as a light yellow solid with a melting point of 104-106 °C. The product was analyzed by infrared spectroscopy (IR, film) showing characteristic absorption peaks located at 1675 cm?1, 1500 cm?1 and 1340 cm?1. The nuclear magnetic resonance hydrogen spectroscopy (1H NMR, 400 MHz, CDCl3) data are as follows: δ 2.18-2.25 (2H, m, CH2), 2.75 (2H, t, J = 6.8 Hz, CH2), and 3.10 (2H, t, J = 6.1 Hz, CH2), 7.45 (1H, d, J = 8.4 Hz, ArH), 8.30 (1H, dd, J = 2.4 Hz, 8.4 Hz, ArH), 8.86 (1H, d, J = 2.4 Hz, ArH).
