Potassium Carbonate → Tert-butyl {2-[(1-ethylnaphthalen-2-yl)oxy]ethyl}carbamate

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To a solution of 1-ethylnaphthalen-2-ol (780 mg, 4.53 mmol) and K2CO3 (626 mg, 4.53 mmol) in 15 mL of acetonitrile was added tert-butyl (2-bromoethyl)carbamate (1.015 g, 4.53 mmol). The resulting mixture was heated at reflux overnight. After TLC control (n-hexane/ethyl acetate 7:3) showed the disappearance of 1-ethylnaphthalen-2-ol, solvent was evaporated in vacuo and the residue was dissolved in 15 mL of ethyl acetate and washed with water (3×5 mL), brine (5 mL) and dried over Na2SO4. The evaporation of solvent afforded tert-butyl {2-[(1-ethylnaphthalen-2-yl)oxy]ethyl}carbamate which was dissolved in 10 mL of 4M HCl in dioxane and stirred for 1 h. The solvent was removed under vacuum and the residue was diluted with n-hexane (20 mL) and triturated at room temperature for 2 h. The solid was filtered and dried under vacuum at 50° C. to afford 2-[(1-ethylnaphthalen-2-yl)oxy]ethanaminium chloride as brown solid (821 mg, 72% yield). To a solution of 2-[(1-ethylnaphthalen-2-yl)oxy]ethanaminium chloride (100 mg, 0.397 mmol) in 10 mL of MeOH, K2CO3 (65 mg, 0.47 mmol) was added. After 10 min, 48 μL (0.58 mmol) of furan-2-carbaldehyde were added. The resulting solution was stirred for 1 h at room temperature, added with sodium borohydride (15 mg, 0.397 mmol) and allowed to stir for further 2 h at room temperature. The solvent was evaporated under vacuum. The crude product was purified by flash chromatography on silica gel (CH2Cl2/MeOH 97:3) to afford 2-[(1-ethylnaphthalen-2-yl)oxy]-N-(furan-2-ylmethyl)ethanamine as a brown solid (91 mg, 78% yield).

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