L1???(CH2)n???L2???(II) where L1 and L2 may be same or different and represent a leaving group such as Cl, Br, I, methanesulfonate, trifluoromethanesulfonate, p-toluenesulfonate and the like or L2 may also represent a hydroxy or a protected hydroxy group which may be later converted to a leaving group; n represents an integer ranging from 1-4.