The reaction of 4-amino-1H-imidazole-5-carbonitrile (I) with trimethyl orthopentanoate (II) in hot DMF gives methyl N-(5-cyano-1H-imidazol-4-yl)pentanoimidate (III), which is then cyclized with benzoic hydrazide (IV) in hot DMF to yield the target triazolo-purine derivative.