Pd-catalyzed allylic substitution of purin-8-yl(allyl) acetate: Route to (E)-alkenylpurines

Abstract

C8-Alkenylpurines were synthesized starting from purin-8-yl(allyl) acetates using Pd-catalyzed allylic substitution. The described protocol allows, by reaction of purin-8-yl(allyl) acetates with stabilized nucleophiles, an access to novel (E)-8-alkenylpurine derivatives under Pd2dba3·CHCl3 catalysis in dry THF in yields ranging from 31 to 76%. A wide range of nucleophiles showed exclusive E-alkene formation, however, ethyl nitroacetate gave mixture of E/Z-alkenes. On contrary, purin-2-yl(allyl) acetates reacted smoothly only with dimethyl malonate.