PREPARATION OF SOME DERIVATIVES OF 5-AZACYTIDINE AND 2'-DEOXY-5-AZACYTIDINE

Acetylation of 2',3',5'-tri-O-benzoyl-5-azacytidine (3) gave N-4-acety l derivative 4 which was hydrolyzed to the formylamidinourea 5. The sa me compound was obtained by ribosylation of the silylated triazine 6 a nd subsequent hydrolysis of the product. The acetyl derivative 9 was p repared via silylated 5-azacytidine 10. Acid catalyzed acetylation of 5-azacytidine 1 afforded the triacetate 11. Reaction of I or its 2'-de oxy derivative 2 with N,N-dimethylformamide dimethyl acetal gave dimet hylaminomethylene derivatives 13 and 12, respectively. Acid catalyzed reaction of 1 with 2,2-dimethoxypropane, trimethyl orthoformate or tri ethyl orthoformate gave the respective 2',3'-O-isopropylidene, 2',3'-O -methoxymethylene or 2',3'-O-ethoxymethylene derivatives of 1. Selecti ve deacylation of the 3',5'-di-O-p-toluylate 17 gave the 3'-O-p-toluoy late 18; by contrast monoacylation of 2 gave predominantly the 5'-O-p- toluoylate 19.