ZnCl2 (2.0 eq.) was added to the reaction mixture. The reaction mixture proceeded under microwave conditions (100 W, 300 psi, 160 °C) for 5 min. After completion of the reaction (observed by TLC), the reaction mixture was extracted between 2M NaOH (100 mL) and DCM (3 × 100 mL). The organic phases were combined, dried over anhydrous Na2SO4, and filtered. The filtrate was concentrated under reduced pressure, and the reaction mixture was purified by flash chromatography using DCM/MeOH/25% aqueous NH3 (20:1:0.1) as the mobile phase. Compound 3 was obtained as a free base with a 92% yield.