To 16 mg of the product of Example 1 in 1,4-dioxane (1 mL) was added 0.5 mL of 1 M aqueous HCl solution. The reaction stirred at 50° C. for 5 hours. LC/MS indicated little product forming and an additional 0.2 mL of concentrated HCl solution was added. The temperature was increased to 90° C. for 4.5 hours at which point the reaction was cooled to room temperature and diluted with EtOAc. The solution was washed with saturated aqueous NaHCO3 solution before drying with Na2SO4 and concentrating. The residue was purified by preparative TLC (silica gel) eluted with 20% EtOAc in CH2Cl2 affording the title compound. HPLC/MS: 471.9 (M+1), 473.9 (M+3); Rt=4.32 min.
