Synthesis of 3,7-Dideaza-2′-deoxyadenosine and Related Pyrrolo[3,2-c]pyridine 2′-Deoxyribo- and 2′,3′-Dideoxyribonucleosides

A number of new pyrrolo[3,2-c]pyridine 2′-deoxynucleosides including 3,7-dideaza-2′-deoxyadenosine (1), 3,7-dideaza-2′-deoxyinosine (2), and 3,7-dideaza-2′-deoxynebularin (3) were synthesized from 4,6-dichloro-1-(2-deoxy-β-D-erythro-pentofuranosyl)-1 H- pyrrolo[3,2-c]pyridine(10). The latter was obtained stereoselectively via solid-liquid phase-transfer glycosylation¹ of the nucleobase 7 with the halogenose 8. Compound 10 was converted into the pyrrolo[3,2-c]pyridine 2′,3′-dideoxyribofuranoside 14 via a four-step deoxygenation procedure. From compound 14, 3,7-dideaza-2′,3′-dideoxyadenosine (4) was obtained upon nucleophilic displacement of the 4-chloro substituent followed by reductive removal of the 6-chloro substituent. 3,7-Dideazapurine 2′-deoxynucleosides (1H-pyrrolo[3,2-c]pyridine 2′deoxynucleosides) are extremely stable against acid or base.