The product of step (a) (2.0 g, 5.26 mM) was dissolved in THF (30 mL), methanol (10 mL), and water (10 mL). The mixture was treated with lithium hydroxide (882 mg, 21.04 mM) and the mixture was stirred at room temperature for 3 hours. The mixture was concentrated to 15 mL and the pH was adjusted to about 3.0 with 1 N HCl. The mixture was extracted 3 times with ethyl acetate (25 mL). The ethyl acetate fractions were combined, dried over MgSO4, filtered and concentrated to provide the title compound.
