Preparation, structural characterization, and acid-catalyzed isomerization of 3-, 7-, and 9-benzyl-6-benzylthiopurines

Article abstract of DOI:10.1002/jhet.5570310669

Benzylation of 6-benzylthiopurine was examined. Structural assignments of the products were determined by 1-D and 2-D nmr spectroscopy (HMQC, HMBC, and nOe). In the presence of base, the isomeric N3-, N7-, and N9-benzylated products 4, 3, and 2 were isolated; however, only 9-benzyl-6-benzylthiopurine (2) was obtained in the absence of base. In the latter case, the initially formed N3- and N7-isomers were, in the presence of acid, converted to 9-benzyl-6-benzylthiopurine (2) via a 6-benzylthiopurine intermediate as evidenced by analysis of the reaction over time using reversed-phase hplc.