The acylation of 6-amino-5-(benzylamino)-2-methylpyrimidine-2,4(1H,3H)-dione (I) with 5-methylhexanoic acid (II) by means of EDCI and DMAP gives the amide (III), which is cyclized by means of hot POCl3 affording the chloropurin-6-one (IV). The condensation of (IV) with the chiral aminoalcohol (V) by means of DIEA and NMP yields intermediate (VI), which is cyclized by means of SOCl2 in dichloromethane providing the imidazo-purine (VII). Finally, this compound is debenzylated with ammonium formate and Pd(OH)2.