Synthesis and properties of some hydrazo- and oxamido-bridged purine nucleosides

Abstract

In a search for further long-bridged purine cyclonucleosides suceptible to further chemical transformations, 8,2′-hydrazo-9-(2′-deoxy-β-D-arabinofuranosyl)adenine (8a), and its hypoxanthine (8b) and guanosine analogues (8c) have been synthesized from 8-bromo-2′-O-tosyladenosine and other analogous precursors with an excess of hydrazine. Compound (8a, b) were oxidized to the corresponding 2′,N^β-didehydrocyclonucleosides (9a, b). Sodium methoxide catalysed aerial oxidation of (8a) and (8b)[or or (9)] gave the triazinopurines (10a) and (10b). To elucidate the mechanism of the conversion of (8) into (10), the 5′-O-trityl analogues (12) and (13) were also synthesized. 8,3′-Aminoimino-(16) and 8,2′-oxamido-adenine cyclonucleosides (19) have also been synthesized.