Synthesis of Nucleoside Libraries on Solid Support. II. 2,6,8‐Trisubstituted Purine Nucleosides Using 8‐Bromoguanosine as Precursor

A series of 2,6,8‐trisubstituted purine nucleoside libraries was prepared by parallel solid‐phase synthesis using 8‐bromoguanosine as a common synthetic precursor. Polystyrene‐methoxytrityl chloride resin was linked to the N2 or O5′ position of the guanosine analogues. 8‐Bromoguanosine was derivatized at the C8 position via carbon‐carbon bond formation. Nucleophilic aromatic substitution at C2 and/or C6 positions with various amines produced two series of purine nucleoside libraries with very diverse substitution. †In honor and celebration of the 70th birthday of Professor Leroy B. Townsend.