An efficient procedure for the alkylation, diazotization and oxyalkylation of 2-amino-6-chloropurine to 2-Chloro-6-methoxy-9-alkylpurine compounds in good to excellent yield is reported. The synthesized compounds were characterized by MS, 1H NMR and elemental analysis. The effects of solvent, mole ratio of raw material, catalyst and reaction temperature on the alkylation reaction were discussed, and the yields of the compounds of this step were more than 76% under optimized conditions that n (2-amino-6-chloropurine): n (bromoalkane) = 1:3, n (bromoalkane): n (K2CO3) = 1:1.5, reaction temperature was 20℃ with DMF as solvent.