To a solution of example 5-1 (7.2 mg, 0.0144 mmol) in anh. MeOH (1 mL) and anh. CH2Cl2 (2 mL), at r.t., under N2, was added 25% NaOH (40 μL). The reaction mixture was stirred at r.t. for 30 min. It was then poured into sat.aq. NaHCO3 and CH2Cl2 was added. The phases were separated and the aqueous layer was further extracted with CH2Cl2 (2×10 mL). The combined organic extracts were dried over anh. Na2SO4, the solids were filtered and the solvent evaporated to give the title compound (6.4 mg, quantitative yield) as a white solid.
