Ethyl acetate (0.94 g, 7.8 mmol) was slowly added to a solution of sodium ethoxide (1.1 g, 15.6 mmol) in anhydrous ethanol (8 mL) at 0 °C. Subsequently, 1-chloro-3,4-dihydronaphthalene-2-carbaldehyde (1.5 g, 7.8 mmol) was added dropwise to the above reaction mixture and the reaction system was stirred at room temperature overnight. After completion of the reaction, the mixture was refluxed for half an hour and then poured into pre-cooled brine and extracted with ethyl acetate (3 x 60 mL). The organic phases were combined, washed with saturated brine (2 x 50 mL) and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the crude product was purified by recrystallization from ethanol to give 1.3 g of the yellow solid product ethyl 4,5-dihydronaphtho[1,2-b]thiophene-2-carboxylate in 66.3% yield.
