SYNTHESIS OF NOVEL ACYCLONUCLEOSIDES - REACTIONS OF 1-(1-BROMO-2-OXOPROPYL)PYRIDAZIN-6-ONES OR (3-BROMO-2-OXOPROPYL)PYRIDAZIN-6-ONES

Reaction of 1-(3-bromo-2-oxopropyl)pyridazin-6-ones 1 and 2 with sodium azide at room temperature gave the corresponding 1-(3-azido-2-oxopropyl)pyridazin-6-ones 3 and 4, whereas reaction of 1-(1-bromo-2-oxopropyl)pyridazin-6-ones 5 and 6 with excess sodium azide afforded 4-azido-5-chloropyridazin-6-one 7 and 4,5-diazido-3-nitropyridazin-6-one 8 by dealkylation. Some 1-(2-hydroxypropyl)pyridazin-6-ones 9, 10, 11 were synthesized from the corresponding 1-(2-oxopropyl) derivatives 1, 2, 3. 4,5-Dichloro-1-(2,3-dihydroxypropyl)-pyridazin-6-one 13 was also prepared from compound 9 via the corresponding 2,3-epoxypropyl derivative 12. Treatment of compound 5 with thiourea gave 4,5-dichloro-1-(2-amino-4-methylthiazol-5-yl)pyridazin-6-one 14. Reaction of compounds 1 and 2 with thiourea at 20-degrees afforded the corresponding 3-formamidinylthio-2-oxopropyl derivatives 15 and 16, whereas treatment of compound 1 with thiourea at 45-degrees gave 4,5-dichloro-l-[(2-aminothiazol-5-yl)methyl]pyridazin-6-one 17. Compound 17 was also prepared from compound 15 by refluxing in ethanol.