Synthesis of Certain 5‐Substituted 2′‐Deoxytubercidin Derivatives

The synthesis of the 7‐deaza‐2′‐deoxy‐adenine derivatives 7b–3 with chloro, bromo, or methyl substituents at C(5) is described. Glycosylation of the 5‐substituted 4‐chloropyrrolo[2,3‐d]pyrimidines 4b–d with 2‐deoxy‐3,5‐di‐O‐(4‐toluoyl)‐α‐D‐erythro‐pentofuranosyl chloride (3) gave the β‐D‐nucleosides 5b–d, exclusively. They were deblocked (→6b–d) and converted into the tubercidin derivatives 7b–d.