Benzyl Bromide → Tert-butyl 4-(benzyloxy)phenethylcarbamate

Participants

Reaction Steps

To a suspension of potassium carbonate (K2CO3; 1.4 grams (g), 10.11 millimole (mmol)) in acetone (40 milliliters (mL)) was added bromomethylbenzene (1.73 g, 10.11 mmol) and tert-butyl 2-(4-hydroxyphenyl)ethylcarbamate (2 g, 8.4 mmol). The reaction mixture was heated at reflux for 15 hours (h) and then concentrated in vacuo. The residue was partitioned between diethyl ether (Et2O) and water (H2O), and the organic fraction was washed with brine, dried over sodium sulfate (Na2SO4), suction filtered, and concentrated in vacuo. The residue was purified by silica gel (SiO2) flash chromatography with 25% Et2O in hexane to afford [2-(4-benzyloxyphenyl)-ethyl]-carbamic acid tert-butyl ester as a white solid (2.4 g). This was dissolved in CH2Cl2 (50 mL) and trifluoroacetic acid (5 mL) was added. After stirring 16 h, the solvent was removed in vacuo, and the residue was redissolved in CH2Cl2, washed with 1M sodium hydroxide (NaOH), dried (Na2SO4) and filtered. The solvent was removed in vacuo to yield 2-(4-benzyloxyphenyl)-ethylamine (1.5 g). This was used without purification in the next step.

Provenance & Evidence