A one-step synthesis of regioisomeric N-and O-benzylated 8-bromoguanines 4, 5, 9, 10 via N 2 -acetyl-8-bromoguanine (2) is described. The possibility to prepare 8-oxo-and 8-chloroguanine derivatives 3, 11, 12 from the same compound 2 is demonstrated. 1 H and 13 C NMR spectra are used to locate the sites of aralkylation.

Alkylations of 9- and 7-[(2-acetoxyethoxy)methyl]-N2-acetylguanine with alkyl halogenides in the presence of base have been investigated affording a new route to the preparation of 1,N2-dimethyl- as well as O6-benzyl-9(7)-alkoxyalkylguanines. 1H NMR spectra revealed that the 1,N2-dimethyl derivatives exist as mixtures of two conformers at room temperature due to the restricted rotation about the C2-N2 bond. These findings agreed with conformational calculations.

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The N-alkoxyalkylation of 8-bromo-N'-acetylguanine I with α-halogen and a-acetoxy ethers has been investigated. Treatment of I with 2-haloethyl chloromethyl ethers in the presence of potassium carbonate afforded 8-bromo-7-and 8-bromo-9-alkoxyalkyl-N 2 -acetylguanines in high overall yields. Without added base the replacement of the bromine atom for chlorine at the 8 position of the heterocycle occurred providing 8-chloro-7-and 8-chloro-9-alkoxyalkylated products. The acid catalyzed reaction of I with 2-acetoxyethyl acetoxymethyl ether afforded 8-bromo-7-and 8-bromo-9-(2-acetoxyethoxymethyl)-N 2 -acetylguanines.