The compound of formula VII can be converted into the corresponding compound of formula IB by reacting it with a compound of the formula R17Z, wherein R17 is defined as R10 is defined above, and Z is a leaving group such as a halo or sulfonate (e.g., chloro, bromo, mesylate or tosylate), in the presence of a base such as an alkali metal hydride, hydroxide or carbonate, preferably potassium hydroxi