SYNTHESIS OF 2-DEOXY-BETA-D-RIBONUCLEOSIDES AND 2,3-DIDEOXY-BETA-D-PENTOFURANOSIDES ON IMMOBILIZED BACTERIAL-CELLS

Alginate gel-entrapped cells of auxotrophic thymine-dependent strain o f E. coli catalyze the transfer of 2-deoxy-D-ribofuranosyl moiety of 2 '-deoxyuridine to purine and pyrimidine bases as well as their aza and deaza analogs. All experiments invariably gave beta-anomers; in most cases, the reaction was regiospecific, affording N9-isomers in the pur ine and N1-isomers in the pyrimidine series. Also a 2,3-dideoxynucleos ide can serve as donor of the glycosyl moiety. The acceptor activity o f purine bases depends only little on substitution, the only condition being the presence of N7-nitrogen atom. On the other hand, in the pyr imidine series the activity is limited to only a narrow choice of most ly short 5-alkyl and 5-halogeno uracil derivatives. Heterocyclic bases containing amino groups are deaminated; this can be avoided by conver sion of the base to the corresponding N-dimethylaminomethylene derivat ive which is then ammonolyzed. The method was verified by isolation of 9-(2-deoxy-beta-D-ribofuranosyl) derivatives of adenine, guanine, 2-c hlorodenine, 6-methylpurine, 8-azaadenine, 8-azaguanine, 1-deazaadenin e, 3-deazaadenine, 1-(2-deoxy-beta-D-ribofuranosyl) derivatives of 5-e thyluracil, 5-fluorouracil, and 9-(2,3-dideoxy-beta-D-pentofuranosyl)h ypoxanthine, 2,3-dideoxy-beta-D-pentofuranosyl)-6-methylpurine, and ot her nucleosides.