General procedure. TBDMS deprotection

The substrate (0.3 g) was dissolved in 6 mL (1:1) solution of methanol:hydrochloric acid (6N) and refluxed for 5 h. The reaction mixture was cooled to 0°C and neutralized with saturated aq. sodium bicarbonate. The organic layer was extracted with ethyl acetate (3 × 20 ml), washed with water (2 × 25 mL), brine (25 mL), dried over magnesium sulfate and evaporated to obtained crude product which was purified by flash chromatography using methanol:dichloromethane:ammonium hydroxide (2:97.5:0.5).