Purines. LXXI. Preparation and Alkylation of 7-Alkyladenine 1-Oxides : A General Synthesis of 1-Alkoxy-7-alkyladenines

7-Methyladenine (6a) and 7-ethyladenine (6b) afforded the N(1)-oxides 7a, b in 78% yield each on treatment with m-chloroperoxybenzoic acid at room temperature; this is analogous to the previously reported N-oxidation of 7-benzyladenine (6c) to give the N(1)-oxide 7c. When treated with an excess of methyl iodide, ethyl iodide, or benzyl bromide in N, N-dimethylacetamide at room temperature, each of the 1-oxides 7a-c underwent alkylation almost exculsively at the oxygen atom of the N-oxide group. The products, isolated in good yields, were the salts 8d-l·HX of the nine 1-alkoxy-7-alkyladenines, in which either the O-alkyl or the N(7)-alkyl group is any one of methyl, ethyl, and benzyl. The UV and 1H-NMR spectral data for 8·HX and some of their free bases 8 are presented.