Occurrence of the SNANRORC Mechanism in the Amination of 2-Substituted Purines with Potassium Amide in Liquid Ammonia

Article abstract of DOI:10.1021/jo01303a004

The reactions of 2-chloro-, 2-fluoro- and 2-(methylthio)purine with potassium amide in liquid ammonia lead to the formation of 2-aminopurine.When these reactions are carried out with ¹⁵N-labeled potassium amide, ring-labeled 2-aminopurine is found.This demonstrates that a ring opening occurs during the amination.Formation of an anionic ? adduct at position 6 is proven by low-temperature NMR spectroscopy, and evidence is obtained for the formation of an open-chain intermediate, although this intermediate could not be isolated in a pure state.Reaction of the open-chain intermediate with hydriodic acid gives the thus far unknown 2-iodopurine. 2-Chloro-6-phenylpurine also reacts via ring opening into 2-amino-6-phenylpurine.However, 2-chloro-6-methyl- and 2-chloro-6,8-di-tert-butylpurine are found to be unreactive.