SYNTHESIS OF 6-SUBSTITUTED PURINE N-7-(2-DEOXY-BETA-D-RIBONUCLEOSIDES) VIA ANION GLYCOSYLATION AND ANOMERIZATION DURING THE N-7 N-9-GLYCOSYL TRANSFER/

The synthesis of the 7-(2-deoxy-beta-D-erythro-pentofuranosyl) adenine (Ib) as well as the corresponding hypoxanthine- and purine nucleoside s 3 and 4 is described employing the stereoselective nucleobase anion glycosylation. The N-7/N-9- isomer distribution of the 6-substituted p urine (2-deoxyribonucleosides) depends on 6-substituent. Glycosyl tran sfer of 8a resulted in anomerization and yielded a mixture of the anom eric 6-methoxypurine N-9-(2-deoxy-D-ribonucleosides) 7a/7d. The prefer red glycosylic bond conformation of purine N-7-(2-deoxyribonucleosides ) is anti.