On the Mechanism of Alkaline Hydrolysis of Methylthiopurines

Di- and trimethylthiopurines, which can form anions, are resistant to alkaline hydrolysis. After introduction of an N-methyl substituent, these compounds are incapable of forming anions and become susceptible to attack by hydroxyl ion. The course of these reactions can be predicted satisfactorily by Fukui's superdelocalizabilities for nucleophilic attack; the same order of reactivities is derived for analogous methylthio- and chloropurines, in accordance with the limited experimental observations.