TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The catalyst is chosen from lithium bromide, sodium bromide, potassium bromide, lithium iodide, sodium iodide, ammonium chloride and potassium bromide, preferably potassium iodide or sodium iodide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The 3-methyl-3,7-dihydro-1H-purine-2,6-dione compound (IV) is free from alkali, organic acid or inorganic acid. The 3-methyl-3,7-dihydro-1H-purine-2,6-dione compound (IV) is piperidine and piperazine salt chosen from 65 piperidine and piperazine salts e.g. malonate, mandelate, methanesulfonate, naphthalene-1,5-disulfonate, benzenesulfonate, benzoate, 4-acetamido-benzoate, dodecyl sulfate, ethane-1,2-disulfonate and ethanesulfonate. The aromatic compound (I) is chosen from 27 aromatic compounds e.g. hexadecyl trimethyl ammonium bromide, hexadecyl dimethyl ammonium bromide, tributyl methyl ammonium chloride, tributyl methyl ammonium bromide, triethyl ammonium bromide, triethyl ammonium chloride, t-propyl ammonium chloride, t-propyl ammonium bromide, tetraethyl ammonium bromide and tetraethyl ammonium chloride. The tertiary amine is pyridine or triethylamine. The quaternary phosphonium salt is chosen from 15 quaternary phosphonium salts e.g. phenyl methyl allyltriphenylphosphonium, triphenyl methyl phosphonium, triphenyl ethyl phosphonium, triphenyl ethyl allyltriphenylphosphonium and propyl phosphonium. The solvent is chosen from tetrahydrofuran, 2-methyl tetrahydrofuran, methyl isobutyl ketone, n-butyl alcohol, tertiary butyl alcohol, isoamyl alcohol, toluene, xylene, chlorobenzene, ethyl acetate, butyl acetate, isopropyl acetate, propyl acetate, butyl acetate, isobutyl acetate, methyl tertiary butyl ether, isopropyl ether, diphenyl ether, cyclohexane, normal hexane and normal heptane. Preferred Process: The 2,3,6,7-tetrahydro-1H-purine derivative is subjected to 3-amino de-protection process to obtain 8-(3-aminopiperidin-1-yl)-7-(but-2-yn-1-yl)-3-methyl-1-((4-methylquinazolin-2-yl)methyl)-2,3,6,7-tetrahydro-1H-purine-2,6-dione. Preferred Definitions:    X1=bromo;    X2=chloro;    X3=bromo or chloro;and    R5,R6=H, t-butoxycarbonyl, 9-fluorenyl methoxy carbonyl or phthaloyl.