[Synthesis]
GENERAL METHODOLOGY: Step 4: To a solution of compound 60 (3.0 g, 8.0 mmol) in methanol (100 mL) was added a methanol solution of 3N hydrochloric acid (8.0 mL, 24 mmol). The reaction mixture was stirred at room temperature for 1 hour and then concentrated under reduced pressure by rotary evaporator. The concentrate was diluted with ethyl acetate (30 mL) and subsequently filtered to collect the solid. The solid was washed with ethyl acetate (20 mL) to afford compound 62a (880 mg, 57% yield) as a white solid. The product was characterized by 1H NMR (500 MHz, CD3OD): δ 7.50 (m, 1H), 7.32-7.28 (m, 2H), 7.19 (m, 1H), 7.41 (m, 1H), 3.93 (m, 1H), 3.82 (m, 1H). lcms (ESI) m/z: 156.1 [M+H]+. |