[0552] p is 1 or 2, with 2 being preferred; and [0553] R4 is a hydroxyl group, or a protected hydroxyl group. [0554] The present invention also provides compositions comprising a compound of formula XIIIA-D wherein X3 has the formula XI and p is 2, said composition being substantially free of a compound of formula XIVA, XIVB, XIVC, or XIVD: [0555] wherein: [0556] W14 has the formula: [0557] Also