Branching of poly(ADP-ribose): Synthesis of the Core Motif.

The synthesis of the core motif of branched poly(adenosine diphosphate ribose) (poly(ADPr)) is described, and structural analysis reasserted the proposed stereochemistry for branching. For the synthesis, a ribose trisaccharide was first constructed with only α-O-glycosidic linkages. Finally, the adenine nucleobase was introduced via a Vorbrüggen-type glycosylation reaction. The orthogonality of the selected protecting groups was demonstrated, allowing for the construction of branched poly(ADPr) oligomers in the near future.