The reaction of 2-amino-6-chloropurine (I) with 1,4-diazabicyclo[2.2.2]octane (II) in DMSO gives 1-(2-aminopurin-6-yl)-4-aza-1-azoniabicyclo[2.2.2]octane chloride (II), which is condensed with cyclohexylmethanol (III) by means of NaH in DMSO.