Treatment of anthranilic acid 1 or 3-amino 2-naphthoic acid 5 with butyl isocyanate in THF led to the formation of the ureido derivatives 3 and 7 respectively, which were cyclized to the corresponding diones 4 and 8 by refluxing in DMF, while the treatment of 1 or 5 with butyl isocyanate in DMF afforded the same diones 4 and 8 respectively. Treatment of 2,4-Bis (trimethylsilyloxy) quinazoline 9 with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)quinazoline-2,4(1H-3H)-dione 11. Debenzolation led to the free nucleoside 12. Structural proofs of the prepared compounds are based on spectroscopic methods.