348165-62-8

348165-61-7

348165-62-8

Compound 15 (0.885 g, 2.51 mmol) was dissolved in methanol (5 mL) followed by addition of tetrahydrofuran (5 mL) and 2N sodium hydroxide solution at room temperature. The reaction mixture was stirred for 30 min, poured into water and extracted with ethyl acetate. The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give compound 13 (0.52 g, 100% yield) as a colorless solid.