General procedure for the synthesis of (S)-N,N-dimethyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine oxalate from 1-fluoronaphthalene, oxalic acid and R-3-(dimethylamino)-1-(2-thiophenyl)-1-propanol: R-3-(dimethylamino)-1-(2-thiophenyl)-1-propanol (2.0 g, 0.011 mol) was was dissolved in dimethylacetamide (100 mL) and a suspension of 60% sodium hydride (463 mg, 0.012 mol) was added slowly and dropwise. The reaction mixture was heated at 70°C with stirring for 20 minutes. Subsequently, 1-fluoronaphthalene (1.27 mL, 0.012 mol) was added dropwise to the reaction system and heating was continued with stirring at 110 °C for 60 min. After completion of the reaction, the reaction mixture was diluted with water and extracted twice with ether. The organic phases were combined, washed sequentially with water and saturated sodium chloride solution, and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure to give the oily product (S)-N,N-dimethyl-3-(naphthalen-1-yloxy)-3-(thiophen-2-yl)propan-1-amine (3.28 g, 75.6% yield).
