SYNTHESIS OF 5-AZACYTOSINE 2’-DEOXYRIBONUCLEOSIDES, PROPERTIES AND BIOLOGICAL ACTIVITY

Abstract

The effect of the o-D anomer Ia on L 1210 mouse leukemia cells was studied. This nucleoside inhibited the cell growth in vitro (IC55 about Lx 10-°m), and was also active in vivo in increasing the life span of mice with L1210 leukemia (800 to 1000 mg/kg) by 100%. It is Supposed that the action of the o-D anomer Ia is due to its conversion to Ib shown by HPCL performed on water solutions of both anomers. Similarly, the conversion of Ib to Ia was observed. Hydrolysis of 2'-deoxy-5-azacytidine (Ib) or its «-D anomer Ia with aqueous ammonia affords N-amidino-N’-(2-deoxyß- D-erythropentofuranosyl)urea formate (IVb). Cyclocondensation Of this compound with dimethylformamide dimethyl acetal leads to a mixture of anomeric nucleosides Ia and Ib. Stannic chloride catalysed condensation of blocked 2-deoxy-D-ribopyranose with silylated 5-azacytosine and subsequent methanolysis of the protected intermediates affords anomeric deoxyribopyranosyl nucleoside Va and vb which do not exhibit biological extivity. A series of 6-substituted deoxy nucleosides was prepared by direct glycosylation and the isocyanate procedure. 6-Amino-2’-deoxy-5-azacytidine prevents the growth of E. coli; the inhibition is completely reversed by natural purine bases and/or nucleosides.