Purines. VI. Reactions of 2-Chloro-and 2- (Methylsulfonyl) -9-phenyl-9H-purines with Nucleophiles

The reactions of 2-chloro-9-phenyl-9H-purine (1) with sodium methoxide, ethoxide, and phenoxide as O-nucleophiles, with butylamine and piperidine as N-nucleophiles, and with sodium methylsulfide as an S-nucleophile, afforded 2-methoxy- (3a), 2-ethoxy- (3b), 2-phenoxy- (3c), 2-butylamino- (4a), 2-piperidino- (4b), and 2-methylthio-9-phenyl-9H-purine (5), respectively. Compound 1 also reacted with ethyl cyanoacetate and phenylacetonitrile as C-nucleophiles in the presence of sodium hydroxide in dimethyl sulfoxide to give ethyl H-cyano-9-phenyl-9H-purine-2-acetate (6a) and α, 9-diphenyl-9H-purine-2-acetonitrile (6b). However, 1 did not react with other active methylene compounds, ketones or potassium cyanide. On the other hand, 2- (methylsulfonyl) -9-phenyl-9H-purine (2), prepared easily from 1, smoothly reacted not only with active methylene compounds but also with ketones and potassium cyanide. When active methylene compounds, such as ethyl cyanoacetate and phenylacetonitrile, were used, 2 gave 6a and 6b in good yields. In the cases of ketones and potassium cyanide, the substitution reactions of 2 proceeded to give the corresponding 2-substituted 9H-purines (7 and 8a-d), as expected.