Compound of Formula IIe (Formula IIa where R15, R16 and R17 are H, R41 is P, R43 is M1(CH2)1-3R1 where M1 is O or NR57) is prepared by reacting compound of Formula IId (Formula IIa where R15, R16 and R17 are H, R41 is P, and R43 is a halogen, R59, e.g. chloro) with a compound of Formula R1???(CH2)1-3???OH or R1???(CH2)1-3???NR57 in the presence of a base (e.g. sodium hydride, potassium carbonate)