Step 1) Preparation of compound B: Compound B: 2-(allyloxy)phenol
Anhydrous potassium carbonate (K2CO3) (6.36 g, 0.046 mol) (6.36 g, 0.046 mol) was added to an anhydrous acetone (20 mL) solution of catechol (Compound A) (5 g, 0.045 mol) in batches over 30 minutes. The reaction mixture was stirred at room temperature for 1 hour. Subsequently, 3-bromo-1-propene (3.84 mL, 0.045 mol) was added slowly and dropwise to the above mixture over 30 minutes. The reaction mixture was heated to 60-70 °C and refluxed for 5 hours. After completion of the reaction, the K2CO3 was removed by filtration. the filtrate was concentrated, extracted with chloroform (3 x 75 mL), the organic phases were combined and washed with brine (1 x 50 mL) and dried with anhydrous sodium sulfate. The crude product was purified by silica gel column chromatography (silica gel; 60-120 mesh) with the eluent being a gradient increasing solvent mixture of chloroform/petroleum ether. The petroleum ether eluate containing 4% chloroform was collected and concentrated to give pure compound B as a viscous orange liquid. Yield: 5.8 g (85%).
1H NMR (300MHz, CDCl3): δ 4.59 (d, J=4.29Hz, 2H), 5.35 (qt, J=17.2,10.46Hz, 2H), 5.69 (s, 1H), 6.04-6.08 (m, 1H), 6.81-6.96 (m, 4H).
Mass spectrum (ESI) m/z: 149 [M-H]-.
