Alkylation of 2-amino-6-chloropurine with 5-(2-bromoethyl)-2, 2-dimethyl-1, 3-dioxane (5) provided 2-amino-6-chloro-9-[2-(2, 2-dimethyl-l, 3-dioxan-5-yl) ethyl] purine (6) in high yield. This aminochloropurine 6 was readily converted to the antiviral acyclonucleoside 9-[4- hydroxy-3-(hydroxymethyl) but-l-yl] guanine (1) and to its 6-chloro (IO), 6-thio (Il), 6-alkoxy (12-17), 6-amino (20), and 6-deoxy (21) purine analogues. The guanine derivative 1 was ...