A new strategy based upon the intramol. SNAr reaction was developed for the synthesis of I, the 14-membered F-O-G macrocyclic ring system of teicoplanin. Thus, treatment of acyclic precursor II (X = F) with CsF or K2CO3/18-crown-6 in DMF at room temp. for 6-20 h gave 62-82% I. Chloride II (R = Cl) gave 80% I on treatment with K2CO3 in DMF at 80 Deg for 6 h. The reason for the easy macrocyclization was advanced and supported by computational studies. [on SciFinder (R)]