Collect. Czech. Chem. Commun. 1996, 61, 645-655

Synthesis of 5-Phenylcytosine Nucleoside Derivatives

Marcela Krečmerová, Hubert Hřebabecký and Antonín Holý

Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic


Reaction of silylated 5-phenylcytosine with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribose, catalyzed with tin tetrachloride, and subsequent methanolysis afforded 5-phenylcytidine (2). This compound reacted with thionyl chloride in acetonitrile to give cyclic sulfite 3 which on heating in dimethylformamide was converted into 2,2'-anhydro-1-(β-D-arabinofuranosyl)-5-phenylcytosine (4). Analogous reaction of compound 2 with thionyl chloride at reflux gave 5'-chloro-5'-deoxy-2',3'-cyclic sulfite 5. Its heating in dimethylformamide afforded 5'-chloro-2,2'-anhydro derivative 6, mild alkaline hydrolysis led to 5'-chloro-5'-deoxy-5-phenylcytidine (7). Alkaline hydrolysis of 5-phenyl-2,2'-anhydrocytidine (4) gave 5-phenylcytosine arabinoside 8, whereas the 2,2'-anhydro derivative 6 afforded 1-(5-chloro-5-deoxy-β-D-arabinofuranosyl)-5-phenylcytosine (11). At higher temperature, the final reaction product was 2,5'-anhydro-5-phenylcytidine (12). 5'-Chloro-5'-deoxynucleosides 7 and 11 reacted with tri-n-butyl- stannane to give 5'-deoxyribofuranosyl and 5'-deoxyarabinofuranosyl derivatives 15 and 16. 5-Phenylcytidine (2) was converted into the N4-acetate 17 with acetic anhydride. Further reaction with acetic anhydride and hydrogen bromide in acetic acid afforded a mixture of peracetylated 2'-bromo and 3'-bromo derivatives 18 and 19. Reaction with Zn/Cu couple gave 5'-O-acetyl-5-phenyl-2',3'-didehydro derivative 20 and 2',3',5'-tri-O-acetyl-5-phenylcytidine (21). Compound 20 was deblocked to 1-(2,3-dideoxy-β-D-glycero-pent-2-enofuranosyl)-5-phenylcytosine (22). Catalytic hydrogenation of compound 20 over palladium and subsequent deblocking of the protected 2',3'-dideoxy derivative 23 gave 1-(2,3-dideoxy-β-D-glycero-pentofuranosyl)-5-phenylcytosine (24).

Keywords: 5-Phenylcytosine; Nucleosides; Pyrimidine; 2',3'-Dideoxynucleoside.